failure analysis

Composite Material Testing for Drone UAV Applications with DGCA Requirements

Kartik Srinivas failure analysis, life prediction, material testing

The testing requirements for composite materials used in drone applications may differ slightly from those used in manned aircraft, as the safety considerations and regulatory framework can vary. However, many of the fundamental testing principles remain similar. Here are some common composite material testing requirements for drone applications:

Material Testing and Characterization for Different Applications
  1. Material characterization: Basic material properties such as tensile, compressive, shear, and flexural strengths, as well as physical properties like density and fiber volume fraction, need to be determined through standardized testing methods.
  2. Impact resistance: Composite materials used in drone structures should be tested for their resistance to low-velocity impacts, as drones may be subject to collisions with obstacles or debris during flight.
  3. Fatigue testing: Cyclic loading tests are often performed to evaluate the fatigue life and damage propagation characteristics of composite materials under simulated flight conditions.
  4. Environmental resistance: Tests for moisture absorption, thermal aging, and resistance to chemicals or fluids that may be encountered during operation or storage are typically required.
  5. Vibration and acoustic testing: Composite materials may need to be tested for their response to vibrations and acoustic loads experienced during drone flight.
  6. Repair and maintainability: Evaluation of repair techniques and the effects of repairs on the mechanical properties of composite materials may be necessary, particularly for larger or more critical drone components.
  7. Qualification testing: Full-scale or component-level testing may be required to qualify the composite materials and structures for their intended use in drone applications, considering factors such as design loads, operational environments, and safety margins.

It’s important to note that the specific testing requirements may vary depending on the type of drone, its intended use (commercial, military, recreational), and the applicable regulations or standards set by governing bodies or industry organizations. Additionally, composite material suppliers and drone manufacturers may have their own internal testing protocols and acceptance criteria based on their design requirements and risk assessments.

The Directorate General of Civil Aviation (DGCA) in India has set specific requirements for the testing of composite materials used in the aviation industry. These requirements are aimed at ensuring the safety and reliability of aircraft components made from composite materials. Here are some key aspects of the DGCA’s composite material testing requirements:

Material characterization: The DGCA requires comprehensive material characterization tests to be performed on composite materials, including tests for mechanical properties (tensile, compressive, shear, and flexural strengths), physical properties (density, fiber volume fraction), and environmental resistance (moisture absorption, thermal aging).
Damage tolerance testing: Composite materials must undergo damage tolerance testing to assess their ability to withstand and resist the propagation of defects, such as impact damage, delaminations, and fatigue cracks. These tests may include compression after impact (CAI), open-hole compression (OHC), and fatigue testing.
Environmental testing: Composite materials must be tested for their performance under various environmental conditions, such as elevated temperatures, humidity, and exposure to chemicals and fluids commonly encountered in aviation applications.
Fire resistance testing: Composite materials used in aircraft interiors must meet specific fire resistance requirements, including tests for smoke density, heat release rate, and flame propagation.
Quality control and process control: The DGCA requires manufacturers to establish and maintain robust quality control and process control procedures for the fabrication of composite components. This includes the use of appropriate manufacturing techniques, inspection methods, and non-destructive testing (NDT) techniques.
Certification and approval: Composite materials and components intended for use in aircraft must undergo a rigorous certification and approval process by the DGCA. This process involves the review of design data, test reports, and manufacturing procedures to ensure compliance with applicable airworthiness standards.

It’s important to note that the specific testing requirements may vary depending on the application and criticality of the composite component, as well as the type of composite material being used. Manufacturers and suppliers of composite materials and components for the aviation industry in India must comply with the DGCA’s regulations and guidelines to obtain the necessary approvals for their products.

AdvanSES provides all the testing recommended by Directorate General of Civil Aviation (DGCA), contact us for a free quote for your testing requirements.

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

Kartik Srinivas failure analysis, fea abaqus ansys, Materials Engineering and FEA

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

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

Kartik Srinivas failure analysis, life prediction, material testing, Materials Engineering and FEA, service life prediction

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.

Plastic Material Testing: Ensuring Quality and Safety

Kartik Srinivas failure analysis, fea abaqus ansys, life prediction, material testing, Materials Engineering and FEA
AdvanSES Testing Laboratory

Plastic Material Testing: Ensuring Quality and Safety

Plastic materials have become an integral part of our lives, from the packaging of our daily essentials to the construction of our homes and buildings. However, the use of plastics has also raised concerns about their impact on the environment and human health. Therefore, it is essential to test plastic materials to ensure their quality and safety. At AdvanSES plastic material testing is carried out under the strict and rigorous quality control as per ISO 17025:2017 testing conditions.

Plastic material testing involves analyzing the physical, chemical, and mechanical properties of plastic materials. These tests provide valuable information about the durability, strength, and chemical resistance of plastics, which are critical factors in determining their suitability for specific applications.

Types of Plastic Material Testing

Fatigue Testing at AdvanSES

There are various types of plastic material testing, each serving a specific purpose. The most common types of tests include:

  1. Tensile Testing: This test measures the strength of plastic materials under tension, providing valuable information about their mechanical properties.
  • Impact Testing: This test evaluates the ability of plastic materials to withstand sudden impact, which is critical in applications such as packaging and transportation.
  • Fatigue Testing: This test evaluates the ability of plastic materials to withstand long term service loads, the mechanical service life of the materials and parts can be predicted from fatigue testing.
  • Thermal Analysis: This test measures the thermal properties of plastic materials, such as their melting and crystallization behavior.
  • Chemical Resistance Testing: This test evaluates the resistance of plastic materials to various chemicals, providing important information about their suitability for use in specific environments.
  • Flammability Testing: This test evaluates the ability of plastic materials to resist ignition and combustion, providing critical information for applications such as building construction.

At AdvanSES, we provide plastic and composite material testing under all the above mentioned parameters, you can be worry free about our test data and results as we are ISO 17025:2017 accredited.

Benefits of Plastic Material Testing

Plastic material testing offers numerous benefits, including:

  • Quality Control: Plastic material testing helps to ensure that plastic materials meet quality standards, reducing the risk of product failure and liability.
  • Cost Savings: By identifying potential defects or weaknesses in plastic materials early on, testing can help to reduce production costs and minimize waste.
  • Safety: Plastic material testing ensures that plastic materials are safe for use in specific applications, protecting both consumers and the environment.

    We can provide a quick quote for your plastic and composite material testing needs within a business day, try giving us a call or email and we would be happy to assist with any of your testing needs.

Conclusion

Plastic material testing plays a critical role in ensuring the quality and safety of plastic materials. By analyzing their physical, chemical, and mechanical properties, testing provides valuable information about their suitability for specific applications. By optimizing this blog post for search engines, we can ensure that this important information reaches a wider audience, promoting greater awareness of the importance of plastic material testing.

Low Velocity Impact Testing

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Low Velocity Impact Damage Testing:

Glass and Carbon fiber reinforced thermoplastic composite materials are widely used in automotive, and aerospace applications to make structures light-weight without losing on the stiffness and load carrying capability. Properties like high toughness, high Young’s modulus, low strains, and manufacturability for specific applications make these materials indispensable to modern industry. Most of these applications include high strain, low and high velocity impacts and it becomes imperative to study the behaviour of these materials under such conditions.

AdvanSES offers testing capabilities for testing as per ASTM D7136 (Drop Weight Impact), ASTM D256 (Izod Impact Test), ASTM D6110 (Charpy Impact Test) wherein the damage resistance of these materials and products can be studied. Low Velocity Impact Testing forms one of our core range of services for material and product testing.

Evaluation of Critical Tearing Energy of Rubber Materials

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critical tearing energy rubber

Do you know the critical tearing energy of your rubber material?

Critical tearing energy is an important parameter to study crack growth in rubber under fatigue loading and it’s evaluation becomes imperative for the design and evaluation of rubber products. To prevent crack growth and sudden fatigue failures, one of the technique is to improve the tearing energy of rubber. Evaluation and testing of tearing energy properties is of utmost importance.

In automotive, aerospace and biomedical applications, soft elastomers and rubbers often handle cyclic loads and displacement cycles during their entire service duty cycle. When going through long periods of cyclic loading, catastrophic failure frequently happens becuase of crack formation, growth followed by propagation.

Contact us to evaluate the critical energy of your rubber material. More information at https://www.advanses.com

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AdvanSES Materials Testing Services

Kartik Srinivas failure analysis, fea abaqus ansys, life prediction, material testing

We at AdvanSES are capable of developing a custom testing protocol for compliance with international standards or for quality assurance. Materials testing services offered by AdvanSES include:

Composition: Whe you need to know with certainty what materials are used in the manufacture of thermoplastics, rubber materials etc.

Shear Test: Materials testing designed to measure shear strength of rubber and composites. These tests show how much stress a specimen can take before failure and is often times used to test and compare the strength of adhesives.

Flexural Test: When a product like an I-beam or girder used in construction must support a predetermined amount of weight without sagging, a flexure materials test is often performed to verify that the specimen can withstand a certain level of stress without flexing.

Environment and High Temperature Exposure Test: When it comes to determining the lifespan of materials, especially elastomer materials intended for outdoor use, exposure to high temperature and oils is carried out to check the degradation of materials.

Tensile/Compression Tests: From plastics and metals to adhesives and rubbers, tensile/compression testing is a form of materials testing that places specimens under precise compressive loads to measure their ability to withstand compression before deformation occurs.

Fatigue Tests: Fatigue tests are important to determine the endurance or breaking load a material can withstand before failing as well as the number of repeated loading cycles it can endure. Fatigue testing looks at a materials limit to withstand stresses and environment degradation. We can conduct stress controlled and strain controlled high cycle fatigue tests from room temperature to 250C on material samples, parts and components.

Applications of Materials Testing:

1) Quality Control
2) Regulatory Compliance
3) Design Development
4) Failure Analysis
5) Performance Prediction
6) Finite Element Analysis Material Constants Data

Advanced Scientific and Engineering Services (AdvanSES) Laboratory Earns Renowned ISO/IEC 17025:2017 Accreditation

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AdvanSES announces that its Testing Laboratory has attained ISO/IEC 17025:2017 accreditation vide NABL certificate No. TC-9168. ISO/IEC 17025:2017 is the highest recognized quality standard in the world for calibration and testing laboratories. Accreditation means the lab consistently produces precise and accurate test data and has implemented a rigorous quality management system. The stringent processes in the audits for the accreditation relate to the operations, efficiency and effectiveness of the laboratory. Test data from the laboratory is benchmarked for accuracy, reliability and consistency.

Receiving the accreditation means that test reports and certificates generated from AdvanSES laboratory can now be generally accepted from one country to another without further testing. 

The scope of the accreditation covers tests and properties in the field of rubbers, plastics and composite materials. It is one of the few labs in the world accredited to perform internationally recognized fatigue standards like ASTM D7791.

AdvanSES today is one of the few companies in the world who provide expert problem solving services using Finite element analysis (FEA), provides new product development and material testing and analysis.

National Accreditation Board for Testing & Calibration Laboratories (NABL) provides accreditation to Conformity Assessment Bodies (Laboratories). NABL Schemes include Accreditation (Recognition) of Technical competence of testing, calibration, medical testing laboratories, Proficiency testing providers (PTP) & Reference Material Producers (RMP) for a specific scope following ISO/IEC 17025, ISO 15189, ISO/IEC 17043 & ISO 17034:2016[3] Standards. It has Mutual Recognition Arrangement (MRA) with Asia Pacific Laboratory Accreditation Cooperation (APLAC), International Laboratory Accreditation Cooperation (ILAC).

NABL is a constituent board of Quality Council of India which is an autonomous body setup under Department for Promotion of Industry and Internal Trade (DPIIT), Ministry of Commerce and Industry, Government of India

Static and Dynamic Testing of Engineering Materials and Components

Kartik Srinivas failure analysis, life prediction, material testing

Static and dynamic testing of engineering materials and products involves mechanical loading of a material specimen or product up to a pre-determined deformation level or up to the point where the sample fails. The material properties backed out from these tests are further used to characterize the materials and products. Testing is carried out under essentially two conditions viz; Static and Dynamic.

Physical testing of materials as per ASTM D412, ASTM D638, ASTM D624 etc., can be categorized as slow speed tests or static tests. The difference between a static test and dynamic test is not only simply based on the speed of the test but also on other test variables and parameters employed like forcing functions, displacement amplitudes, and strain cycles. The difference is also in the nature of the information we back out from the tests. Static mechanical testing is carried out at lower frequencies, generally less than one Hertz. The associated loads and applied deformation amplitudes are also smaller and the strain rate is much lower as compared to typical engineering applications. Dynamic loading is generally carried out under forcing functions and with high deformation amplitudes. These forcing functions and amplitudes are applied under a very short time period. When related to polymers, composites and elastomers, the information from a conventional test is usually related to quality control aspects of the materials or products, while from dynamic tests we back out data regarding the functional performance of the materials and products. ASTM D5992, D4092 and D5279 are some of the dynamic mechanical testing standards. High speed tensile, compression, impact, fracture tests using Split Hopkinson Pressure bars (SHPB), Servo-Hydraulic testing machines and cyclic fatigue tests fall under the category of dynamic testing.

Polymer materials are widely used in all kinds of engineering applications because of their superior performance in vibration isolation, impact resistance, rate dependency and time dependent properties. In some traditional applications they have consistently shown better performance combining with other materials like glass fibres etc., and are now replacing metals and ceramics in such applications. The investigations of polymer properties in vibration, shock, impact and other viscoelastic phenomena is now considered critical, and understanding of dynamic mechanical behaviour of polymers becomes necessary. Static and dynamic testing of engineering materials and components becomes imperative for this purpose.

Figure 1: Static and Dynamic Testing Systems at AdvanSES

The absolute values from frequency sweep, strain sweep, temperature sweep dynamic tests are meaningful, but have little utility as isolated data points. They do become valuable data points when compared to each other or some other known variables. A tan delta or damping coefficient value of 0.4 is poor for a natural rubber or EPDM based compound, but very good in FKM materials where the structure of the compound makes it venerable to lower than optimum dynamic properties. Most uncured rubbery compounds start on the viscous side, and as we cure the compound, we shift towards the elastic side.

The importance of dynamic testing comes from the fact that performance of elastomers and elastomeric products such as engine mounts, suspension bumpers, tire materials etc., cannot be fully predicted by using only traditional methods of static testing. Polymer and elastomer tests like hardness, tensile, compression-set, low temperature brittleness, tear resistance tests, ozone resistance etc., are all essentially quality control tests and do not help us understand the performance or the durability of the material under field service conditions. An elastomer is used in all major applications as a dynamic part being able to provide vibration isolation, sealing, shock resistance, and necessary damping because of its viscoelastic nature.

Figure 2: Viscoelastic and Dynamic Studies Correlate Molecular Structure to Manufacturing and Mechanical Properties of Engineering Components

As it stands today, the theory of dynamic properties can be applied judiciously to product development, performance characterization or failure analysis problems. The field of application has evolved over time with availability of highly sophisticated instruments. The problems need to be studied upfront for any time or frequency dependent loading conditions and boundary conditions acting on the components and the theory be suitably applied. Needless to say that dynamic properties have utmost importance when polymeric materials and components show heat generation, and fatigue related field failures. Dynamic characterization relates the molecular structure of the polymeric materials to the manufacturing processes and to the field performance of engineering products. Dynamic properties play an important part in comparing mechanical properties of different polymers for quality, performance prediction, failure analysis and new material qualification. Dynamic testing truly helps us to understand and predict these properties both at the material and component level.

Following are the testing modes that can be implemented in the static and dynamic testing of engineering materials and the results on can back out;

Test Modes:

No.Test ModesTests
1.OscillationFrequency Sweep, Strain Sweep, Stress Sweep, Temperature Sweep, Fatigue Test
2.Stress ControlCreep, Fatigue
3.Strain ControlStress Relaxation, Fatigue, Crack Growth
4.Rate ControlStress ramp and Strain ramp

Test Results Data:

1) Storage or Elastic Modulus (E’) versus temperature, frequency, or % strain

2) Loss or Viscous Modulus (E”) versus temperature, frequency, or % strain

3) Damping Coefficient (Tan Delta) versus temperature, frequency, or % strain

4) Stress vs Strain properties at different strain rates.

5) Strain vs Number of Cycles for a material or component under load control fatigue.

6) Load or Stress vs Number of Cycles for a material or component under strain control fatigue.

7) Fatigue crack growth vs Number of Cycles for a material under strain controlled fatigue.

No single testing technique or methodology provides a complete picture of the material quality or component performance. It is always a combination of testing methods and techniques that have to be applied to obtain a 360 degree view of the material quality and performance.

References:

1) Ferry, Viscoelastic Properties of Polymers, Wiley, 1980.

2) Ward et al., Introduction to Mechanical Properties of Solid Polymers, Wiley, 1993.

3) TA Instruments, Class Notes and Machine Manuals, 2006.

4) Lakes, Roderick., Viscoelastic Materials, Cambridge University Press, 2009.

5) Srinivas, K., and Pannikottu, A., Material Characterization and FEA of a Novel Compression Stress Relaxation Method to Evaluate Materials for Sealing Applications, 28th Annual Dayton-Cincinnati Aerospace Science Symposium, March 2003.

Polymer Testing for Aerospace Applications

Kartik Srinivas failure analysis, fea abaqus ansys, life prediction, material testing

Space research and application demands stringent requirements from materials, making it imperative that they are tested rigorously, by multiple methods and techniques to fully characterize their performance and their ability to handle degradation, mechanical fatigue under extreme conditions.

AdvanSES provides full mechanical characterization of specialty polymers, rubber and in-homogeneous materials, for use in demanding atmospheric and space applications. Mechanical fatigue testing is a core area for us and we can test materials for HCF, LCF as well as elevated temperatures.

We can provide the following testing protocols for your rubbery materials;

1) Uniaxial Tension Test as per ASTM D412
2) Compression Test as per ASTM D575
3) Tear Test as per ASTM D624
4) Crompression Stress Relaxation Test as per ASTM D6147
5) Dynamic Viscoelastic Test ASTM D5992
6) Hyperelastic Material Constants
7) Axial Fatigue as per ASTM D7791