Application of engineering polymers and plastics are widespread because of the wide range of material properties, and lower manufacturing cost offered by them. Plastics and polymers are also mixed with glass and carbon fibers to increase the stiffness and provide higher load handling capabilities. Polymer Testing & Finite Element Analysis FEA go hand in hand for such material and product development.
Thermosetting plastics are used in the manufacture of hard, high temperature resistanting parts and a matrix for composites is used for strength and stiffness. Elastomers such as natural rubber are used in automotive applications for vibration isolation and load bearing properties.
Finite Element Analysis FEA of polymer testing is critical to understanding the perfomance of polymer materials and their judicious use in industrial products. Design optimization iterations are then carried out to finalize the design for optimum stress-strain distribution and high fatigue life.
Polymers exhibit a combination of elastic and viscous response to deformation forces. At low temperatures the stiff elastic behaviour is dominant. At high temperatures a viscous or fluid like behaviour is exhibited. At room temperatures a combination of viscous and elastic behaviour (Viscoelastic) is exhibited. The challenge is to test, model and simulate this unique behaviour of this class of material so that the complete material property can be mapped on the product.
The Izod Charpy impact test is an ASTM and ISO standard method of determining the impact resistance of thermoplatic and composite materials and is an important test for characterization of materials. The test is very much similar to the Charpy impact test but uses different type of specimens for testing. The Izod impact test differs from the Charpy impact test in that the test sample is held in a cantilevered beam configuration as opposed to a three-point bend configuration. Both notched and un-notched Izod Charpy impact test provide important material properties.
The testing conditions are governed by many parameters, as below:
the dimensions of the usually rectangular cross section of the sample below the notch;
the height of the hammer at the start position, determining its velocity at impact;
the mass of the hammer which together with the velocity determines its kinetic energy at impact;
the sharpness, or tip curvature, of the notch;
the temperature of the sample.
Results of impact tests are expressed in terms of:
Amount of energy absorbed (N-m) or
Amount of energy absorbed per unit cross sectional area (N-m/cm2)
Measure of the energy required to crack the material.
Test materials and grade them as per their impact property and use the grading for different applications.
AdvanSES offers Fatigue Testing of Materials and Products using a variety of stress and strain controlled testing machines for characterizing field service behaviors of engineering products, medical devices, and automotive aerospace components.
Fatigue testing involves the application of cyclic loading to a test specimen or a product. Unlike monotonic tests in which loading increases until failure, the applied load is cycled between prescribed maximum and minimum levels until a fatigue failure occurs, or until the predetermined number of loading cycles have been applied.
The loading is applied to assess long term fatigue behavior, vibration isolation properties, and observe failure causing mechanisms.
AdvanSES offers Fatigue Testing of Materials and Products for;
1) Material Samples 2) Full Scale Component Level Testing 3) Measure Material and Product Degradation 4) Elevated Temperature Testing 5) Incorporation of Aging Mechanisms in Testing
Benefits of Fatigue Testing at AdvanSES
With material and product testing at AdvanSES, you can be sure of:
Materials Testing Laboratory at AdvanSES uses highly precise, repeatable and reliable techniques that quantify and measure quality control and performance characteristics of materials, such as mechanical properties, design properties and durability properties
Our material testing laboratory is ISO 17025:2017 accredited and equipped to age, test and analyze materials for a wide-range of industries and applications. We can perform testing as per ASTM, ISO standards and also as per your specified criteria. Our test data and results help design engineers make better designs. Our test data help scientists and engineers determine whether materials, products and aging criteria meet the requirements of design engineers, quality control department and whether they products and materials are suitable for their intended applications.
We can mold, machine and creat test specimens and samples for efficient turnaround. We can also mold and manufacture these test specimens for your own in-house material testing.
ALL ABOUT QUALITY
AdvanSES material testing laboratory is ISO 17025:2017 accredited. Any kind of samples can be tested at our laboratory using the latest techniques. We can mould specimens, extract samples from failed or in field service products, age and make any kind of samples for your testing convenience.
AdvanSES provides answers to your material questions that meet your quality requirements:
Advanced Scientific and Engineering Services (AdvanSES) delivers Expert Finite Element AnalysisFEAservices to assist design engineers, quality control personnel, and manufacturers in developing innovative products and solving their design, development and structural challenges. We provide optimized engineering designs, and resolve multi-disciplinary failure analysis problems.
Design Development and FEA Studies
Our Expert Finite Element Analysis (FEA) services engineers are committed to your deadlines and bringing your products faster to the market. We take your product specifications like load, displacement, fatigue life requirements and convert them to products that perform within the design specifications.
A finite element analysis is only as good as the accuracy of the material properties, boundary conditions, geometry representation and loading conditions. Our verification checks and validations include mesh convergence analysis, design constraint check, load path checks and validations with testing.
Backed by Laboratory Testing and Domain Experts
Finite element analysis FEA simulations of parts and components is validated with our laboratory testing. This methodology provides a robust and thorough verification and validation of your product development and analysis process and it provides you with real world data of your products performance envelope. Mechanical testing of materials is used to provide a complete 360 degree view of the material performance.
Proven Performance and Quality
AdvanSES’ long history of services, benchmark performance, and consistent quality is the result of an unwavering commitment to scientific and engineering excellence. AdvanSES customers around the world, from design engineers to manufacturers enjoy complete confidence in the proven performance of our laboratory and professional services. We are an ISO 17025:2017 accredited material testing laboratory with commitment to quality, and customer service excellence.
A New Approach to Product Development & Rapid Prototyping
The procedure of manufacturing objects by depositing successive layers upon layers of material, based on 3D digital CAD models, is called Additive Manufacturing (AM) or simply 3D-printing. Fused Deposition Modeling (FDM) technology is one of the most widely used technique in additive manufacturing. A range of other manufacturing materials can be used for 3D printing that include nylon, glass-filled polyamide, epoxy resins, wax, and photopolymers. FDM-based polymer product manufacturing has increased in recent times due to the flexibility it offers in the production of polymer and fibre-based composite parts. FDM-based polymers have the potential to be used in all applications, currently they are primarily used in automotive, aerospace and biomedical applications.
Additive Manufacturing involves a series of processes, from ideation and design development to final product manufacturing using a specialized printer. The different steps depend on the type of manufacturing method and the material type. The primary processes and steps involved are however mostly common and remain the same for different types of manufacturing applications. The steps involved in an AM process are as shown below;
Fused Deposition Modeling (FDM)
FDM is the method of choice for manufacturing of 3d printed polymer parts and components due to its simple process, low economic cost and predictable material properties. FDM is already used in the material extrusion manufacturing process for various thermoplastic polymers. Some common thermoplastic filaments used in FDM are acrylonitrile butadiene styrene (ABS), polypropylene (PP), polylactide (PLA), polyamides (PA) like Nylon, polyether-ether-ketone (PEEK) etc. The FDM process consists of the polymer being extruded and deposited in a successive layer by layer method. FDM manufactured polymer parts and components exhibit good mechanical properties, surface finish, and manufacturability. The matrix material used in the FDM process is in the form of a 1.75mm to 2.85 mm filament wound on a spool. The filament is fed into the printer head where it is heated and melted above its glass transition temperature (Tg). The plastic melt is then passed to the nozzle and deposited layer by layer.
FDM of Fibre-Reinforced Polymers
The strength of polymeric materials can be significantly improved through reinforcement by fibres. Fibre-reinforced polymers manufactured using 3d printing technique is gaining traction. Fibre-matrix interaction and porosity are important considerations to be addressed in 3d printing of polymeric composites. FDM is currently the most preferred method for the production of polymeric fiber composites due to its material flexibility, and consistent properties.
Although the 3d printing additive manufacturing method is a sophisticated process for producing materials, and readily usable components and parts, the field service material behaviour of these printed parts is highly complicated. These properties are influenced by several process parameters such as filament material, temperature, printing speed. The material behaviour is highly anisotropic and is governed by the microstructure produced while depositing the layers and the ambient environment. The resulting material behaviour can be described using stress–strain relationships and is critical in the Finite element analysis and stress analysis of models. AdvanSES has full capability to test these complex materials and their behaviours using an array ot techniques. Mechanical testing of 3D printed parts and materials is now a key part of our portfolio of services
Mechanical Testing of 3D Printed Parts and Materials generally involves the following tests:
The properties of plastics and rubber products are closely related to their composition, fillers used, processing aids additives, processing methods, etc. In order to fully understand the performance of the plastics and rubber products, it is necessary to conduct wide ranging tests on these plastics and rubber products. At AdvanSES, we are a plastic rubber testing laboratory and fully equipped to utilize these test methods and provide a full 360 degree of your material and product performance.
As a trusted laboratory partner, we offer you advanced plastic and rubber testing solutions along with the expertise of our qualified engineers. The static, dynamic and fatigue testing conducted at our laboratory ensures safe, reliable and efficient use of your polymeric materials and products in demanding end applications.
Testing of 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 and compulsory.
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.
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 and the results for materials and components that one may seek from dynamic testing;
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.
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, Ohio, March 2003.
Rubber and different types of polymer materials are widely used for a variety of applications, such as vibration isolation mounts, seals, o-rings and gaskets, shock mounts, and tires. The mechanical properties of these materials allow them to act as excellent dampers providing high compliance over a long fatigue life.
This course provides a brief overview of different types of rubber and polymer materials in the automotive and biomedical industries. The main focus of this short class is to teach the attendees to:
Introduction to Polymers and Rubber materials for Engineering Applications.
Non-linear Rubber Elasticity.
Hyperelastic Strain Energy Functions.
Mechanical Material Testing and Curve Fitting in FEA Softwares (Theory and Application).
Questions and Answers Session.
This course is recommended for design engineers, FEA analysts, engineers working with new product development etc.