Challenges in Mechanical Testing of Composite Materials

Challenges in Mechanical Testing of Composite Materials

Mechanical Testing of Composite Materials

While mechanical testing as per different ASTM and ISO standards provides invaluable data for the design and analysis of composite structures, there are several challenges associated with testing these heterogeneous and anisotropic materials:

1. Material Variability: Composite materials exhibit inherent variability due to factors such as fibre misalignment, voids, and resin-rich or resin-starved regions. This variability can lead to significant scatter in the mechanical properties, making it challenging to establish reliable design allowables.

Dynamic UTM with Temperature Controlled Chamber

2. Specimen Preparation: Preparing high-quality composite test specimens is crucial for obtaining accurate and repeatable results. Factors like specimen geometry, machining-induced defects, and fibre waviness can influence the test results, necessitating strict adherence to specimen preparation procedures.

3. Gripping and End-Effects: In tensile and compressive testing, the gripping of composite specimens can introduce stress concentrations, premature failures, and spurious results if not addressed properly. Special gripping techniques, such as adhesive bonding or tabbing, are often required to minimize gripping-related issues.

Composite Material Testing

4. Failure Modes: Composite materials can exhibit complex failure modes, including fibre breakage, matrix cracking, delamination, and their interactions. Interpreting and correlating these failure modes with the measured properties can be challenging, especially under multi-axial loading conditions.

5. Size Effects: The mechanical properties of composite materials can be influenced by the specimen size and geometry, making it difficult to extrapolate coupon-level test results to full-scale structural components or assemblies.

6. Environmental Factors: The influence of environmental factors, such as temperature, moisture, and chemical exposure, on the mechanical properties of composites can be significant. Accurately simulating and accounting for these effects during testing is crucial for predicting real-world performance.

7. Specialized Equipment: Mechanical testing of composite materials often requires specialized equipment, such as environmental chambers, high-temperature furnaces, and advanced instrumentation for strain measurement and damage monitoring, which can be costly and complex to operate.

8. Data Interpretation and Analysis: The analysis and interpretation of mechanical test data for composite materials can be intricate, involving advanced analytical techniques, failure criteria, and micromechanical models, necessitating expertise in composite material behaviour and failure mechanisms.

9. Anisotropy: Unlike metals, composites often have different properties in different directions, making testing more complex. Addressing these challenges requires a combination of rigorous testing procedures, advanced instrumentation, statistical analysis techniques, and a deep understanding of composite material behavior. Collaboration between material suppliers, testing laboratories, and design engineers is essential to overcome these challenges and ensure the reliable and safe implementation of composite materials in aerospace applications.

Contact us for a free quote for your material testing needs.

Poisson’s Ratio Testing of Composite Materials as per ASTM D3039

Understanding Poisson’s Ratio Testing for Composite Materials per ASTM D3039

Poisson’s ratio testing is an important material property that measures the negative ratio of transverse to axial strain. In other words, it quantifies how much a material contracts in the transverse direction when stretched in the axial direction. Knowing the Poisson’s ratio is critical for analyzing the behavior of materials under different loading conditions.

For fiber-reinforced polymer composite materials, Poisson’s ratio testing is performed according to the ASTM D3039 standard titled “Standard Test Method for Tensile Properties of Polymer Matrix Composite Materials.” This standard covers the determination of tensile properties of reinforced polymer composites under controlled conditions.

Testing Procedure The basic procedure for Poisson’s ratio testing as per ASTM D3039 involves the following steps:

  1. Specimen Preparation: Flat test specimens are prepared from the composite laminate with specified dimensions and geometry. Common specimen types are straight-sided or dog-bone shaped.
  2. Strain Measurement: Strain gauges or extensometers are attached to the specimen in both the axial (loading) and transverse directions to measure longitudinal and lateral strains simultaneously during loading.
  3. Tensile Loading: The specimen is mounted in the tensile testing machine grips and loaded in uniaxial tension until failure occurs. The load and strain data are recorded continuously.
  4. Calculations: From the recorded strain data, Poisson’s ratio is calculated as the negative ratio of lateral strain to axial strain within the elastic region of the stress-strain curve.
Poisson’s Ratio Testing of Composite Materials as per ASTM D3039

Importance of Poisson’s Ratio Accurately determining Poisson’s ratio is crucial for several reasons:

  1. Stress Analysis: Poisson’s ratio influences the stress distribution and deformation behavior of composite structures under different loading conditions.
  2. Failure Prediction: Knowledge of Poisson’s ratio aids in predicting failure modes, such as delamination or matrix cracking, in composite materials.
  3. Finite Element Modeling: Poisson’s ratio is an essential input parameter for finite element analysis (FEA) simulations used in the design and analysis of composite components.
  4. Material Characterization: Poisson’s ratio provides insights into the microstructure and anisotropic nature of fiber-reinforced composites.

Adherence to the ASTM D3039 standard ensures consistent and reliable testing procedures, enabling accurate determination of Poisson’s ratio for composite materials. This data is invaluable for engineers and researchers working on the design, analysis, and optimization of composite structures in various industries, including aerospace, automotive, and renewable energy.

Please contact us to get your materials tested for Poisson’s Ratio

Verification and Validation of FEA for Composite Materials

Errors and uncertainties in the application of FEA for Composite Materials can come from the following many sources,

1) Errors that come from the inherent assumptions in the FEA theory and

2) Errors and uncertainties that get built into the system when the physics we are seeking to model gets transferred to FEA models.

A common list of these kind of errors are as mentioned below;


> Errors and uncertainties from the solver.
> Level of mesh refinement and the choice of element type.
> Averaging and calculation of stresses and strains from the primary solution variables.
> Approximations in the material properties of the model.
> Approx. and uncertainties in the loading and boundary conditions of the model.


The long list of error sources and uncertainties in the procedure makes it desirable that a framework of rules and criteria are developed for the application of finite element method.
Verification procedure includes checking the design, the software code and also investigate if the computational model accurately represents the physical system. Validation is more of a dynamic procedure and determines if the computational simulation agrees with the physical phenomenon, it examines the difference between the numerical simulation and the experimental results. Verification provides information whether the computational model is solved correctly and accurately, while validation provides evidence regarding the extent to which the mathematical model accurately correlates to experimental tests.



The blue, red and green colored areas in Figure highlight the iterative validation and verification activities in the process. The green highlighted region falls in the domain of the laboratory performing the experiments.


Comparing the issue of code verification and calculation verification of FEA for Composite Materials, the main point of difference is that calculation verification involves quantifying the discretization error in the simulation. Code verification is rather upstream in the process and is done by comparing numerical results with analytical solutions.


The validation procedure has to be developed by the analyst. The following validation guidelines were developed at Sandia National Labs [Oberkampf et al.] by experimentalists, these are applicable to all problems from computational mechanics.


#1: The validation experiment should be designed by the FEA group & experiment engineers. The experiments should be designed so that validation falls inside the application domain.
#2: The designed experiment should involve the full physics of the system, including the loading and boundary conditions.
#3: The solutions of the experiments and from the computational model should be totally independent of each other.
#4: The experiments and the validation process should start from the system level solution to the component level.
#5: Care should be taken that operator bias or process bias does not contaminate the solution or the validation process.

Strain Gauging for Verification of Finite Element Analysis

Finite Element Analysis (FEA) is a powerful tool used in engineering to simulate the behavior of structures and materials under different conditions. However, the accuracy of FEA results depends on the accuracy of the input parameters and assumptions made during the simulation. Strain gauging is a technique used to verify the accuracy of FEA results by measuring the actual strains in a structure and comparing them with the predicted strains from the FEA model.

What is Strain Gauging?

Strain gauging is a technique used to measure the strain in a material or structure. A strain gauge is a device that changes its electrical resistance when subjected to strain. The change in resistance is proportional to the strain, and this relationship is used to calculate the strain in the material. Strain gauges are attached to the surface of the material using a special adhesive, and the electrical resistance is measured.

There are several types of strain gauges used for different applications. Some of the common types include:

    Linear Strain Gauges: These have one measuring grid and measure the strain in one direction. They are suitable when only one direction of strain needs to be investigated.

    Quarter-Bridge, Half-Bridge, and Full-Bridge Configurations: These are determined by the number of active elements in the Wheatstone bridge and the type of strain being measured. Quarter-bridge, half-bridge, and full-bridge strain gauges are used to measure bending and axial strain, and they have different sensitivities and applications.

    Rosette Strain Gauges: These include membrane rosette, tee rosette, rectangular rosette, and delta rosette. They are used to measure strain in multiple directions and are suitable for complex stress analysis.

    Shear Strain Gauges, Column Strain Gauges, and 45°/90°-Rosette: These are used for specific applications where the strain needs to be measured in a particular direction or orientation.

Each type of strain gauge has its own characteristics, advantages, and applications. The selection of the appropriate strain gauge depends on the specific measurement task and the type of strain to be measured.

How is Strain Gauging Used for Verification of FEA?

Strain gauging is used to verify the accuracy of FEA results by measuring the actual strains in a structure and comparing them with the predicted strains from the FEA model. The process involves the following steps:

  • Design and fabricate the structure to be tested.
  • Install strain gauges at critical locations on the structure.
  • Apply a known load or deformation to the structure.
  • Measure the strains using the strain gauges.
  • Compare the measured strains with the predicted strains from the FEA model.
  • Adjust the FEA model parameters and assumptions to improve the accuracy of the predictions.

Benefits of Strain Gauging for Verification of FEA

Strain gauging is a valuable technique for verifying the accuracy of FEA results. Some of the benefits of strain gauging include:

  • Provides a quantitative measure of the accuracy of FEA results.
  • Helps identify errors in the FEA model parameters and assumptions.
  • Improves confidence in the FEA results and reduces the risk of failure in the actual structure.
  • Can be used to optimize the design of the structure by identifying areas of high stress or strain.

Conclusion

Strain gauging is a valuable technique for verifying the accuracy of FEA results. It provides a quantitative measure of the accuracy of the FEA model and helps identify errors in the model parameters and assumptions. By using strain gauging to verify FEA results, engineers can improve confidence in the design of structures and reduce the risk of failure.

References:

Helm JD, Sutton MA, McNeill SR. Deformations in wide, center-notched, thin panels, part II: finite element analysis and comparison to experimental measurements. Opt Eng 2003; 42(5): 1306–1320.

Hertelé S, de Waele W, Denys R, Verstraete M. Investigation of strain measurements in (curved) wide plate specimens using digital image correlation and finite element analysis. The Journal of Strain Analysis for Engineering Design. 2012;47(5):276-288.

Kartik Srinivas, Verifications and Validations in Finite Element Analysis, https://www.researchgate.net/publication/341727057_Verifications_and_Validations_in_Finite_Element_Analysis_FEA

Composite Material Testing for Drones and UAVs: A Deep Dive

Material Characterization Testing of Drones and UAV Materials at AdvanSES

Composite Material Testing for Drones and UAV Applications

Unmanned Aerial Vehicles (UAVs), commonly known as drones, have revolutionized numerous industries, from agriculture and real estate to cinematography and defense. One of the key factors contributing to the versatility and performance of these drones is the use of composite materials in their construction [1,2]. Composite material testing for drones and UAV applications is both difficult and challenging. The use of fiber-reinforced plastic composite materials challenges drone UAV engineers to design and manufacture products with high strength, stiffness and low cost. The demand for more maneuverable, payload effective UAVs is increasing, where composite materials are playing an essential role in the progress of these new high-performance UAV aircrafts with special composite material characteristics like light weight and high strength. These composite materials are distinguished by Young’s modulus as compared to different kinds of metals and aluminum alloys. Multi-rotor type UAVs represent an extremely complex system in terms of design and control. Octacopter, hexacopter and Quadcopter are typical of such multi-rotor designs. Such a type of aircraft is an inherently unstable system, which results from the fact that it cannot independently return to the point of balance (hover) if it loses the functionality of the control loops but will fall or begin to move uncontrollably in space. Furthermore, multirotor UAVs are nonlinear systems since rotor aerodynamic forces and moment characteristics are nonlinear functions with respect to angular velocities and these reasons make the materials used in the manufacturing to be of high quality, load capacity with an infinite fatigue life for the application designed for.

Why Composite Materials?

Composite Material Layered Construction

Composite materials, such as polymers reinforced with carbon fibers (CFRP) and fiberglass (GFRP), are widely used in the manufacturing of drone components, including the fuselage, wings, and landing gear[1].

Polymer composite materials are widely used in various industries, including the manufacturing of drone UAV components, due to their numerous advantages:

High Strength-to-Weight Ratio: Polymer composites, such as those reinforced with carbon or glass fibers, offer a high strength-to-weight ratio[4]. This property is crucial in applications like drone manufacturing, where reducing weight while maintaining strength can enhance performance[4].

Durability: Composites are known for their durability. They do not rust, have high dimensional stability, and can maintain their shape in various conditions. This makes them suitable for outdoor structures and components that are designed to last for a long time.

Design Flexibility: Composites open up new design options that might be hard to achieve with traditional materials. They allow for part consolidation, and their surface texture can be altered to mimic any finish.

Improved Production: With advancements in manufacturing processes, composites are now easier to produce. Digital Composite Manufacturing (DCM), for instance, has made it possible to fabricate composite parts without manual labor.

Material Stability and Insulation: Polymers used in composites offer high material stability against corrosion, good electrical and thermal insulation, and are easy to shape, making them ideal for economic mass production[4].

These advantages make polymer composites an excellent choice for various applications, including the construction of drone components. However, it’s important to note that the use of these materials also necessitates comprehensive testing to ensure safety, reliability, and durability.

Moreover, compared to traditional materials like aluminum, composites can reduce weight by 15-45%, increase corrosion, fatigue, and impact resistance, and reduce noise and vibrations[1].

Testing Composite Materials

Testing composite materials is a critical aspect of ensuring their performance and reliability in various applications, including drone components. Here are some of the common methods used for testing composite materials:

Mechanical Testing: This includes tensile (tension), flexural, impact, shear, and compression testing[1,2]. These tests help determine the material’s strength and deformation under different types of loads.

Physical Testing: This involves tests like water absorption, density, hardness. These tests provide insights into the material’s physical properties and how they might change in different environments.

Thermal Testing: Dynamic Mechanical Analysis (DMA), and Thermomechanical Analysis (TMA) are used to study the material’s thermal properties2.

Moisture Testing: This includes tests like water absorption and moisture conditioning. These tests are crucial for applications where the material might be exposed to moisture.

Analytical Testing: This includes tests like density of core materials, ignition loss, void content, content analysis, and Fourier Transform Infrared Spectroscopy (FTIR). These tests provide a deeper understanding of the material’s composition and structure.

These tests help manufacturers understand the properties of the composite materials that go into a finished product. Composite material testing for drones and UAV applications is both difficult and challenging. The data derived from these tests can be used to compare the composite materials against conventional materials. It’s important to note that the specific tests used can vary depending on the type of composite material and its intended application

Mechanical Testing & Performance Assessment

Uniaxial Tension Test (Directional) (ASTM D638, ISO 527):

The stress (ζ) in a uniaxial tension testis calculated from;

ζ = Load / Area of the material sample ……………………………………..(1)

The strain(ε) is calculated from; ε = δl (change in length) / l (Initial length) ……………..(2)

The slope of the initial linear portion of the curve (E) is the Young’s modulus and given by; E = (ζ2- ζ1) / (ε2- ε1) ……………………………………..(3)

Uniaxial Tension Testing of Composite Materials

4 Point Bend Flexure Test (ASTM D6272): 

The four-point flexural test provides values for the modulus of elasticity in bending, flexural stress, flexural. This test is very similar to the three-point bending flexural test. The major difference being that with the addition of a fourth nose for load application the portion of the beam between the two loading points is put under maximum stress. In the 3 point bend test only the portion of beam under the loading nose is under stress.

4 Point Bend Flexure Test (ASTM D6272)
4 Point Bend Flexure Test

This arrangement helps when testing high stiffness materials like ceramics infused polymers, where the number and severity of flaws under maximum stress is directly related to the flexural strength and crack initiation in the material. Compared to the three-point bending flexural test, there are no shear forces in the four-point bending flexural test in the area between the two loading pins.

Poisson’s Ratio Test as per ASTM D3039: 

Poisson’s ratio is one of the most important parameter used for structure design where all dimensional changes resulting from application of force need to be taken into account, specially for 3d printed materials. For this test method, Poisson’s ratio is obtained from strains resulting from uniaxial stress only. ASTM D3039 is primarily used to evaluate the Poison’s ratio. Testing is performed by applying a tensile force to a specimen and measuring various properties of the specimen under stress. Two strain gauges are bonded to the specimen at 0 and 90 degrees to measure the lateral and linear strains. The ratio of the lateral and linear strain provides us with the Poisson’s ratio. 

Flatwise Compression Test as per ASTM D695: 

The compressive properties of 3d printed materials are important when the product performs under compressive loading conditions. The testing is carried out in the direction normal to the plane of facings as the core would be placed in a structural sandwich construction. The test procedures pertain to compression call for test conditions where the deformation is applied under quasi-static conditions negating the mass and inertia effects.

Uniaxial Flatwise Compression Testing

The test procedures pertaining to compression call for test conditions where the deformation is applied under quasi-static conditions negating the mass and inertia effects.

Modified Compression Test as per Boeing BSS 7260:

Modified ASTM D695 and Boeing BSS 7260 is the testing specification that determines compressive strength and stiffness of polymer matrix composite materials using a loading compression test fixture. This test procedure introduces the compressive force into the specimen through end loading.

Modified Compression Test as per Boeing BSS 7260

Axial Fatigue Test as per ASTM D7791 & D3479:

ASTM D7791 describes the determination of dynamic fatigueproperties of plastics in uniaxial loading conditions. Rigid or semi-rigid plastic samples are loaded intension (Procedure A) and rigid plastic samples are loaded incompression (Procedure B) to determine the effect of processing, surface condition, stress, and such,on the fatigue resistance of plastic and reinforced composite materials subjected to uniaxial stress for a large number of cycles.The results are suitable for study of high load carrying capability of candidate materials. ASTM recommends a test frequency of 5hz or lower.The tests can be carried out under load/stress or displacement/strain control. The test method allows generation of stress or strain as a function of cycles, with the fatigue limit characterized by failure of the specimen or reaching 10E+07 cycles.The maximum and minimum stress or strain levels are defined throughan R ratio.

Axial Fatigue Test as per ASTM D7791

3 Point Bend Flexure Test (ASTM D790):

Three point bending testing is carried out to understand the bending stress, flexural stress and strain of composite and thermoplastic 3d printed materials. The specimen is loaded in a horizontal position, and in such a way that the compressive stress occurs in the upper portion and the tensile stress occurs in the lower portion of the cross section.This is done by having round bars or curved surfaces supporting the specimen from underneath. Round bars or supports with suitable radii are provided so as to have a single point or line of contact with the specimen. The load is applied by the rounded nose on the top surface of the specimen. If the specimen is symmetrical about its cross section the maximum tensile and compressive stresses will be equal. This test fixture and geometry provides loading conditions so that specimen fails in tension or compression.

3 Point Bend Flexure Test

For most composite materials,the compressive strength islower than the tensile and thespecimen will fail at thecompression surface. This compressive failure isassociated with the localbuckling (micro buckling) ofindividual fibres.

Drop Weight low Velocity Impact Test (ASTM D7136, ISO 6603):

The importance of understanding the response of structural composites to impact events cannot be emphasized enough. Low velocity impact occurs at velocities below 10 m/s and is likely to cause some dents and visible damage on the surface due to matrix cracking and fibre breaking, as well as delamination of the material. In some materials, impact tests characterize the face sheet quality and if they are suitable for the application.

Drop Weight low Velocity Impact Test

Summary:

A variety of standardized mechanical tests on unreinforced and reinforced 3d printed materials including tension, compression, flexural,and fatigue have been discussed.

Mechanical properties of 3d printed polymers, fiber-reinforced polymeric composites immensely depend on thenature of the polymer filament, fiber, and the layer by layer interfacial bonding. Advanced engineering design and analysis applications like Finite Element Analysis use this mechanical test data to characterize the materials. These material properties can be used to develop material models for use in FEA softwares like Ansys, Abaqus, LS-Dyna, MSC-Marc etc.

Conclusion

The use of composite materials in drone manufacturing presents a promising avenue for enhancing UAV performance. However, it also necessitates comprehensive testing to ensure the safety, reliability, and durability of these drones. As the drone industry continues to grow and evolve, so too will the methods for testing and optimizing the use of composite materials in drone construction.

Keywords: UAV, composite materials, drone components, material testing, CFRP, GFRP, finite element analysis, bending test.

References:

  1. M Sönmez, Ce Pelin, M Georgescu, G Pelin, Md Stelescu, M Nituica, G Stoian, Unmanned Aerial Vehicles – Classification, Types Of Composite Materials Used In Their Structure And Applications.
  2. Camil, Lancea et al., Simulation, Fabrication and Testing of UAV Composite Landing Gear. MDPI Journal, https://doi.org/10.3390/app12178598
  3. National Research Council, Airframe Materials and Structures, Enabling Science for Military Systems
  4. Anup Ghosh and Mayank Dwivedi, Advantages and Applications of Polymeric Composites, Processability of Polymeric Composites, Springer, 2019.
  5. Srinivas, Kartik., Mechanical Characterization Testing Of Thermoplastics And Composite Materials, AdvanSES Report, https://www.researchgate.net/publication/339872757_Mechanical_Characterization_Testing_of_Thermoplastics_and_Composite_Materials

Non-linear Hyperelastic Material Characterization Testing for FEA

Non-linear Hyperelastic Material Characterization Testing for FEA

The characterization of materials for Finite Element Analysis (FEA) and Computational Fluid Dynamics (CFD) is a specialized process that involves extensive laboratory testing. At AdvanSES, we have become industry leaders in this field, particularly with our focus on the characterization of polymer materials. Through a series of specific tests, we are able to determine the unique properties of each material, thus providing valuable data for FEA and CFD.

Pure Shear

Our testing process begins with a pure shear test. This involves applying uniaxial tension to a test specimen using either a parallel or tangential method. The response of the material to this stress provides a baseline understanding of its characteristics under tension.

Volumetric Compression

We then proceed to a volumetric compression test. This study involves placing a sample of the material under hydrostatic compression deformation. The way the material responds to this form of stress provides valuable data on its behavior under compression.

Uniaxial Compression

Uniaxial compression testing is another key component of our testing process. Here, we evaluate the response of the material when compression stress is applied along a single axis. This test gives us a clear picture of how the material behaves under a single axis of compression stress.

Uniaxial Tension

Uniaxial tension testing involves applying tensile stress to a specimen. The result of this test provides us with further insights into the behavior of the material under tension.

Biaxial Tension

A biaxial tension test involves placing tensile stress on a specimen in two simultaneous directions. This test is particularly useful in understanding the behavior of a material under multiple tensions.

Creep and Stress Relaxation

The final testing stage is the creep and stress relaxation test. This involves a uniaxial tensile test followed by the maintenance of the elongation on the specimen for a specified duration. By observing the material’s response over this period, we can gain valuable insights into the long-term behavior of the material under stress.

Our laboratory is located at Plot No. 49, Mother Industrial Park, Zak-Kadadara Road, Kadadara, Taluka: Dehgam, District: Gandhinagar, Gujarat 382305, India.

For more information about our services and how we can assist with your material characterization needs, give us a call at +91-9624447567 or send us an email at [email protected].

Engineering Testing of Plastics

Navigating the Frontiers: Engineering Testing of Plastics Unveiled

Engineering Testing of Plastics Unveiled

Introduction:

In the dynamic realm of engineering, where innovation drives progress, the meticulous engineering testing of plastics materials is a cornerstone. Plastics, versatile and ubiquitous, undergo rigorous engineering testing to ensure their reliability, durability, and suitability for diverse applications. In this blog post, we’ll explore the intricacies of engineering testing for plastics, shedding light on the pivotal tests that shape the quality and performance of these materials.

The Engineering Crucible: Why Plastics Testing Matters

Plastics are the backbone of countless engineering applications, from automotive components to medical devices. The success of these applications hinges on the performance and resilience of plastic materials. Engineering testing of plastics becomes imperative to ascertain their mechanical, thermal, and chemical properties, ensuring they meet the stringent standards set by the industry.

Key Engineering Tests for Plastics:

  1. Mechanical Testing:
    • Tensile testing assesses a material’s ability to withstand axial loads, providing insights into tensile strength and elongation.
    • Keywords: plastic tensile testing, material strength, ASTM D638.
  2. Thermal Analysis:
    • Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA) evaluate a plastic’s thermal behavior, including melting points and decomposition temperatures.
    • Keywords: plastic thermal analysis, DSC testing, TGA analysis.
  3. Chemical Resistance Testing:
    • Plastics encounter various chemicals in their applications, and chemical resistance testing ensures they can withstand exposure without degradation.
    • Keywords: plastic chemical resistance, corrosion testing, ASTM D543.
  4. Environmental Stress Cracking Resistance:
    • Measures a plastic’s resistance to cracking when exposed to specific environments, helping predict long-term durability.
    • Keywords: plastic stress cracking, ESC testing, ASTM D1693.
  5. Flammability Testing:
    • Evaluates a material’s response to fire, crucial for applications where fire safety is paramount.
    • Keywords: plastic flammability testing, UL 94, fire resistance.

1.1 Unveiling Strength: A Deep Dive into Mechanical Testing of Plastics

Introduction:

Plastics, the unsung heroes of modern engineering, play a pivotal role in diverse applications. From automotive components to consumer goods, the mechanical strength of plastics is a critical factor in their performance. In this blog post, we embark on a journey into the world of mechanical testing for plastics, unraveling the key tests that ensure these materials can withstand the rigors of real-world applications.

The Essence of Mechanical Testing:

Mechanical testing of plastics is a comprehensive evaluation of their ability to withstand external forces, ensuring they meet the required strength, flexibility, and durability standards. This process is integral to the manufacturing of plastic products, as it provides valuable insights into the materials’ behavior under various stresses and strains.

Key Mechanical Tests for Plastics:

  1. Tensile Testing:
    • Measures the material’s resistance to a force pulling it apart.
    • Keywords: plastic tensile strength, material elongation, ASTM D638.
  2. Flexural Testing:
    • Evaluates a material’s ability to bend without breaking.
    • Keywords: plastic flexural strength, modulus of elasticity, ASTM D790.
  3. Impact Testing:
    • Determines a material’s ability to absorb energy during sudden impact.
    • Keywords: plastic impact resistance, Izod test, ASTM D256.
  4. Hardness Testing:
    • Measures a material’s resistance to indentation.
    • Keywords: plastic hardness, Shore hardness, Rockwell hardness.
  5. Fatigue Testing:
    • Assesses a material’s resistance to repeated loading and unloading cycles.
    • Keywords: plastic fatigue testing, cyclic loading, ASTM D3479.

2.1 Unmasking the Heat: A Comprehensive Guide to Thermal Analysis of Plastics

Introduction:

Plastics, omnipresent in our daily lives, face a myriad of challenges, one of the most critical being their response to heat. Thermal analysis of plastics is a sophisticated process that unveils the intricate details of how these materials react to temperature variations. In this blog post, we embark on a journey into the realm of thermal analysis, deciphering the key tests that shed light on the thermal behavior of plastics and their applications.

Melt Flow Index Testing of Thermoplastic Materials

The Crucial Role of Thermal Analysis:

Thermal analysis is a cornerstone in understanding how plastics respond to temperature changes, helping manufacturers engineer materials that can withstand the diverse thermal challenges they may encounter. Whether it’s in the automotive industry, electronics, or packaging, a thorough understanding of a plastic’s thermal properties is essential for ensuring product reliability and performance.

Key Thermal Tests for Plastics:

  1. Differential Scanning Calorimetry (DSC):
    • Measures the heat absorbed or released during changes in a plastic’s physical state, such as melting or crystallization.
    • Keywords: plastic DSC analysis, thermal transitions, polymer melting point.
  2. Thermogravimetric Analysis (TGA):
    • Determines the weight loss of a plastic as it is heated, providing insights into its thermal stability and decomposition temperatures.
    • Keywords: plastic TGA analysis, thermal degradation, weight loss kinetics.
  3. Dynamic Mechanical Analysis (DMA):
    • Evaluates a plastic’s mechanical properties, such as stiffness and damping, as a function of temperature.
    • Keywords: plastic DMA testing, viscoelastic properties, temperature-dependent modulus.
  4. Thermal Conductivity Testing:
    • Measures a plastic’s ability to conduct heat, crucial for applications where thermal insulation or conductivity is a key factor.
    • Keywords: plastic thermal conductivity, ASTM E1952, thermal insulation.
  5. Oxidative Induction Time (OIT) Testing:
    • Assesses a plastic’s resistance to oxidative degradation at elevated temperatures.
    • Keywords: plastic OIT testing, oxidative stability, polymer aging.

3.1 Safeguarding Integrity: A Deep Dive into Chemical Resistance Testing of Plastics

Introduction:

Plastics, omnipresent in our daily lives, often encounter a variety of chemical substances, from household cleaners to industrial solvents. Ensuring the chemical resistance of plastics is crucial to their performance and longevity. In this blog post, we embark on an exploration of chemical resistance testing, unraveling its importance, key methodologies, and how it safeguards the integrity of plastic materials in diverse applications.

The Importance of Chemical Resistance Testing:

Chemical resistance testing is a critical aspect of material evaluation, particularly for plastics. It involves assessing a plastic’s ability to withstand exposure to various chemicals without undergoing degradation, swelling, or other undesirable changes. Whether used in the pharmaceutical industry, automotive applications, or as packaging materials, understanding chemical resistance is essential for ensuring the reliability and safety of plastic products.

Key Chemical Resistance Tests for Plastics:

  1. Immersion Testing:
    • Involves exposing plastic specimens to specific chemicals for a predetermined period and evaluating changes in weight, dimensions, or appearance.
    • Keywords: plastic immersion testing, chemical exposure test, ASTM D543.
  2. Spot Testing:
    • Applies a small amount of a chemical directly to the plastic surface to observe immediate reactions, providing quick insights into compatibility.
    • Keywords: plastic spot testing, chemical compatibility, quick chemical resistance assessment.
  3. Permeation Testing:
    • Measures the rate at which a chemical permeates through a plastic material, crucial for applications requiring barrier properties.
    • Keywords: plastic permeation testing, barrier material evaluation, ASTM F739.
  4. Elongation at Break Testing:
    • Assesses changes in a plastic’s elongation properties after exposure to chemicals, providing insights into its flexibility and resilience.
    • Keywords: plastic elongation at break, chemical impact on flexibility, ASTM D638.
  5. Volume Swell Testing:
    • Measures the change in volume of a plastic specimen after exposure to chemicals, indicating the extent of swelling or contraction.
    • Keywords: plastic volume swell test, dimensional changes, ASTM D471.
    •  

4.1 Cracking the Code: A Comprehensive Guide to Environmental Stress Cracking Resistance of Plastics

Introduction:

Plastics, ubiquitous in our daily lives, face a unique challenge known as environmental stress cracking (ESC). This phenomenon can compromise the structural integrity of plastic materials when exposed to certain environments and stressors. In this blog post, we delve into the intricacies of Environmental Stress Cracking Resistance (ESCR) testing, exploring its significance, methodologies, and how it safeguards plastics from premature failure in real-world applications.

Understanding Environmental Stress Cracking:

Environmental stress cracking is a process in which a plastic material experiences cracking or crazing when subjected to specific environmental conditions, such as chemical exposure or mechanical stress. This can lead to a significant reduction in the mechanical properties of the plastic and, ultimately, product failure. ESCR testing is designed to assess a material’s resistance to this detrimental phenomenon.

Key Environmental Stress Cracking Resistance Tests for Plastics:

  1. ASTM D1693 – Bent Strip Method:
    • Involves subjecting a bent plastic strip to a chemical environment, assessing the material’s susceptibility to cracking over time.
    • Keywords: plastic environmental stress cracking, ESCR testing, ASTM D1693.
  2. ASTM F2136 – Constant Tensile Load Test:
    • Applies a constant tensile load to a notched plastic specimen immersed in a chemical solution, evaluating the time to failure.
    • Keywords: plastic constant tensile load test, ESC resistance, ASTM F2136.
  3. ASTM D5397 – Notched Constant Tensile Load Test:
    • Similar to the constant tensile load test but introduces a notch to the specimen to accelerate the cracking process.
    • Keywords: plastic notched constant tensile load, accelerated ESC testing, ASTM D5397.
  4. ASTM D2561 – Ball Burst Test:
    • Determines the resistance of plastic sheets to environmental stress cracking by applying internal pressure.
    • Keywords: plastic ball burst test, ESC resistance of plastic sheets, ASTM D2561.
  5. ASTM D7192 – High-Speed Puncture Properties:
    • Assesses a plastic’s resistance to puncture under stress, simulating real-world conditions.
    • Keywords: plastic high-speed puncture test, ESC resistance assessment, ASTM D7192.

5.1 Igniting Safety: A Definitive Guide to Flammability Testing of Plastics

Introduction:

Plastics, omnipresent in our modern world, are subjected to various conditions that include the risk of combustion. Flammability testing of plastics is a critical step in ensuring the safety and compliance of materials used in different applications. In this blog post, we explore the importance of flammability testing, key methodologies, and how it contributes to creating fire-resistant plastic products.

The Significance of Flammability Testing:

Flammability testing is a fundamental aspect of material safety assessment, especially for plastics used in industries such as construction, electronics, and transportation. This testing ensures that plastic materials meet specific fire safety standards, reducing the risk of fire-related incidents and enhancing overall product safety.

Wire Insulation Flammability Testing

Key Flammability Tests for Plastics:

  1. UL 94 – Standard for Safety of Flammability of Plastic Materials:
    • Classifies materials based on their performance in various fire tests, including vertical and horizontal burning tests.
    • Keywords: plastic flammability testing, UL 94 classification, fire safety standards.
  2. ASTM D635 – Standard Test Method for Rate of Burning and/or Extent and Time of Burning of Plastics in a Horizontal Position:
    • Evaluates the burning characteristics of plastics in a horizontal position, measuring burn rate and extent.
    • Keywords: plastic burning rate test, ASTM D635, horizontal burning test.
  3. ISO 9772 – Plastics — Determination of Burning Behaviour by Oxygen Index:
    • Determines the minimum concentration of oxygen that supports the combustion of a plastic material.
    • Keywords: plastic oxygen index, ISO 9772, combustion behavior assessment.
  4. ASTM E1354 – Cone Calorimeter Test:
    • Measures the heat release rate, smoke production rate, and other fire-related parameters under controlled conditions.
    • Keywords: plastic cone calorimeter test, fire performance evaluation, ASTM E1354.
  5. FMVSS 302 – Flammability of Interior Materials:
    • A standard set by the U.S. Federal Motor Vehicle Safety Standards (FMVSS) to assess the flammability of materials used in vehicle interiors.
    • Keywords: plastic flammability in vehicles, FMVSS 302 compliance, automotive safety standards.

Discover more at http://www.advanses.com

At AdvanSES, we provide a full 360 degree static and dynamic characterization of your materials, parts and components. We measure the tension, compression, shear, vibration and dynamic properties of individual components and sub assemblies in accordance to international standards.

More information at https://www.advanses.com

Mechanical Testing of Automotive, Railways, Aerospace components

Installation of mechanical testing structural load frame for carrying out testing high capacity load bearing components. Frames are now available for comprehensive engineering validation of automotive, railways, aerospace components and structures made from polymers, metallic and composite materials.

We can now test and break products and materials from 5N to 500KN.

Discover more at http://www.advanses.com

At AdvanSES, we provide a full 360 degree static and dynamic characterization of your materials, parts and components. We measure the tension, compression, shear, vibration and dynamic properties of individual components and sub assemblies in accordance to international standards.

More information at https://www.advanses.com

Installation of mechanical testing structural load frame for carrying out testing high capacity load bearing components

A Biaxial Test Frame to Aid in Formulation of High-Fidelity Constitutive Models of Rubber Materials

Biaxial tensile testing is a complex, non-traditional but highly accurate testing technique for mechanical characterization of engineering materials. Typical materials tested in biaxial tension are metal sheets, fiber reinforced thermoplastics, thermosets, rubbers and tissues. One of the main reasons that motivates use of biaxial testing is studying the mechanical response for materials to different combinations and rates of stress-strain states, leading to development of constitutive laws that model the underlying materials more accurately. Better quality of constitutive laws provide greater insights into material performance, degradation and failure.

Worldwide many test specifications have been developed for standardized tests on rubber in uniaxial tension, compression, shear and also frequency and strain sweep based dynamic and fatigue tests. However no specific standard or protocol has been developed for biaxial testing of rubber and polymeric thin films. Biaxial tension testing has been traditionally done for metals and composite samples but there are high complexities in carrying out for rubber and thin film material samples. Due to differences in the operating range of the materials, the difference in the nature of applicable loads, and resulting stresses and strains, there have been very few test rigs for specialized biaxial testing of rubbers and thin films. Biaxial test rigs whether in the commercial or academic domain are often customized to serve for specific target materials and their test conditions. Apart from biaxial test rigs, fixtures that provide biaxial deformation and designed to be used on a single axis universal testing machines have also been developed and used.  

Four (4) types of tests can be carried out in the test rig;

  1. Single Stretch.
  2. Multiple Cyclic Loading.
  3. Single Stretch followed by Stress Relaxation Step.
  4. Multiple Cyclic with Stress Relaxation Steps.
Figure 1: AdvanSES Biaxial Loading Test Frame

Heat Deflection Testing of Plastics: Ensuring Material Quality, Reliability and Performance

Introduction:

Plastics are ubiquitous in our daily lives, used in a wide range of applications due to their versatility, durability, and cost-effectiveness. However, when exposed to elevated temperatures, some plastics may deform or lose their structural integrity, compromising their functionality and safety. This is where heat deflection testing plays a crucial role in assessing a plastic material’s ability to withstand heat and maintain its shape under load. In this blog post, we will delve into the importance of heat deflection testing for plastics and explore its significance in ensuring material reliability and performance.

Are you curious about the performance of plastics under high temperatures? Discover the significance of heat deflection testing for plastics, ensuring their reliability and performance in various applications.

Understanding Heat Deflection Testing:

Heat deflection testing, also known as heat distortion testing or HDT, is a standardized method used to evaluate a plastic material’s ability to resist deformation under load at elevated temperatures. It determines the heat deflection temperature (HDT) or the temperature at which a specific deformation or deflection occurs in the plastic specimen. This testing method helps manufacturers and engineers select the most suitable plastic materials for applications involving high temperatures.

AdvanSES VST HDT Apparatus

Importance of Heat Deflection Testing:

2.1. Ensuring Material Reliability:

Heat deflection testing provides vital insights into a plastic material’s ability to maintain its structural integrity when exposed to elevated temperatures. By subjecting plastics to controlled heating and measuring their deformation under load, manufacturers can identify materials that can withstand the intended operating conditions without significant deformation or failure. This ensures that the final products will perform reliably and maintain their shape, avoiding costly failures or safety hazards.

2.2. Performance Optimization:

Different plastics exhibit varying thermal properties, including their response to temperature changes. Heat deflection testing helps engineers optimize material selection for specific applications where exposure to heat is a concern. By comparing HDT values of different plastics, manufacturers can choose materials with higher HDT values that can withstand higher temperatures, resulting in improved product performance and longevity.

 Conducting Heat Deflection Testing:

3.1. Standards and Test Methods:

Heat deflection testing follows established standards such as ASTM D648 (Standard Test Method for Deflection Temperature of Plastics Under Flexural Load in the Edgewise Position) and ISO 75 (Plastics—Determination of Temperature of Deflection Under Load). These standards provide specific guidelines for test specimen preparation, loading conditions, and temperature ramp rates, ensuring consistent and comparable results across different laboratories.

3.2. Test Equipment:

Heat deflection testing requires specialized equipment, typically including a testing machine capable of applying a load on the plastic specimen and a heating chamber or furnace to control the temperature. The test machine measures the deflection of the specimen while it is subjected to a specified load at increasing temperatures until a predefined deflection value is reached.

Applications of Heat Deflection Testing:

Heat deflection testing is essential in numerous industries where plastics are used in high-temperature environments. Some key applications include automotive components, electrical enclosures, consumer electronics, aerospace parts, and industrial equipment. By subjecting plastic materials to rigorous heat deflection testing, manufacturers can ensure the long-term performance and reliability of their products.

Conclusion:

Heat deflection testing is a vital aspect of evaluating plastics’ performance and reliability when exposed to high temperatures. By conducting this testing, manufacturers and engineers can select appropriate materials for specific applications, optimize product performance, and minimize the risk of deformation or failure. Ultimately, heat deflection testing contributes to the overall quality, safety, and longevity of plastic-based products in various industries.

Looking to optimize plastic materials’ performance in high-temperature environments? Contact our experts today to learn how heat deflection testing can enhance the reliability and longevity of your products.