Composites

Compression Testing

Evaluating a composite's ability to withstand crushing forces is essential for many structural applications. A critical challenge in composite manufacturing is the prevention of composite buckling. We employ specialized fixtures and procedures to accurately measure:

• Compressive Strength: The maximum compressive stress a material can withstand.
• Compressive Modulus: A measure of the material's stiffness under compression.

Flexural Testing

Flexural or bend testing evaluates a composite's ability to withstand bending forces. We perform both three-point and four-point bending tests to determine:

• Flexural Strength: The maximum stress experienced within the material at its moment of rupture.
• Flexural Modulus: A measure of the material's resistance to bending deformation.

Impact Testing

Impact testing evaluates how well a composite can handle sudden, strong forces, which is important for situations where impact damage may occur. We perform:

• Izod and Charpy impact tests: Assess the energy absorption capacity of a notched specimen subjected to pendulum impact.
• Drop-weight impact testing: Simulates real-world impact events by dropping a weight onto a composite panel.
• These tests help in evaluating damage resistance and impact energy absorption, providing critical data for material selection in impact-prone applications.

Tensile Testing

Tensile testing is fundamental for determining a composite's strength and stiffness under pulling forces. Understanding the behavior in different fiber orientations (0°, 90°, off-axis) is crucial due to the anisotropic nature of composites. We accurately measure:

• Tensile Strength: The maximum stress a material can withstand before failure.
• Tensile Modulus (Young's Modulus): A measure of the material's stiffness or resistance to deformation.
• Elongation at Break: The percentage of strain at which the material fractures.

To find out more about Tensile Testing with Smither, explore our information on ASTM D638 and/or ASTM D3039.

Shear Testing

Knowing how well a composite can resist forces that make layers slide apart is important for predicting delamination and structural integrity. We offer various shear testing methods:

• In-plane shear: Measures the shear strength within a single layer of the composite.
• Interlaminar shear strength (ILSS): measures the shear strength between composite layers, which is essential to prevent delamination.
• V-notched rail shear is a method for assessing in-plane shear properties, especially useful for specific materials and loading conditions.

Fatigue Testing

Many composite structures are subjected to repeated loading and unloading cycles during their service life. Fatigue testing assesses a composite material's ability to withstand failure when subjected to repeated cycle loading. We perform:

• Tension-tension fatigue: Repeated pulling forces.
• Compression-compression fatigue: Repeated crushing forces.
• Flexural fatigue: The phenomenon caused by repeated bending forces.

The results are often presented as S-N curves, which plot stress amplitude against the number of cycles to failure, allowing for fatigue life prediction.

Why Composites Testing is Important

The very nature of composite materials – their heterogeneity (composed of different materials like fibers and matrix) and anisotropy (properties vary with direction) – makes comprehensive testing indispensable. Unlike traditional isotropic materials, a composite's performance relies heavily on the orientation and properties of its individual components and how they interact.

Our team of experienced engineers and scientists works with a wide range of composite materials, including:

• Fiber-reinforced polymers (FRPs)
• Carbon fiber composites
• Glass fiber composites
• Aramid fiber composites
• Thermoplastic composites
• Thermoset composites

Thorough composite testing is paramount for:

• Material characterization and selection: Evaluating the essential mechanical properties of various composite systems (including fiber type, resin type, and reinforcement architecture) enables engineers to select the most suitable material for the specific requirements of an application. This includes:

  • Spectroscopy (SEM, optical) for detailed examination of microstructure and failure modes.
  • Thermal analysis (DSC, TGA) to evaluate thermal performance and degradation.
• Performance prediction under various service conditions: Simulating real-world stresses and environmental factors through testing allows for accurate prediction of how a composite structure will perform over its expected lifetime.

  • Exposure to humidity: Moisture absorption can weaken the matrix and fiber-matrix interface.
  • Temperature extremes: High and low temperatures can alter the stiffness and strength of the composite.
  • UV radiation: Prolonged exposure can degrade the polymer matrix.
  • Chemical agents: Exposure to solvents, acids, and other chemicals can cause material degradation.
• Quality control during manufacturing: Conducting assessments at multiple stages of the manufacturing process guarantees that the final composite product adheres to the specified standards and that any processing flaws are promptly identified and remedied.
• Failure analysis and prevention: Conducting thorough testing after failures enables the identification of root causes, resulting in enhanced designs, manufacturing techniques, and quality assurance.
• Compliance with industry standards and regulations: Various sectors impose strict standards and regulations concerning the performance and safety of composite materials, necessitating comprehensive testing to ensure adherence. These can include:

  ASTM D2246ASTM D1983ASTM A294D3171(Proced. A)D3171(Proced. B)D3171(Proced. C)D3171(Proced. D)D3171(Proced. E)D3171(Proced. F)ASTM D4762ASTM D1929ASTM D4762ASTM D3171(Proced. G)JN 250ASTM D471ASTM D814ASTM D4049-14ASTM D4049-14ASTM D1501-SS

Mechanical Properties of Composites

Empirical testing yields essential information to confirm the precision of computer-aided design (CAD) and finite element analysis (FEA) models, resulting in enhanced virtual prototyping and design optimization.

Environmental Effects on Mechanical Properties

We conduct testing according to standard test methods (ASTM D5229, ISO 11166) and customized protocols to simulate specific service environments.

• Exposure to humidity: Moisture absorption can weaken the matrix and fiber-matrix interface.
• UV radiation: Prolonged exposure can degrade the polymer matrix.
• Chemical agents: Exposure to solvents, acids, and other chemicals can cause material degradation.

We conduct testing according to standard test methods (ASTM D5229, ISO 11166) and customized protocols to simulate specific service environments.

Product Testing for Composites

For product engineers working with composites, understanding how these advanced materials perform under harsh conditions is paramount. Composite materials testing goes beyond simply standard material characterization to simulate real-world extremes. We can test your large composite specimens under extreme tensions, compressive loading, and shocks, ensuring they perform well in tough situations. This approach delivers crucial data to support designs, predict durability, and confidently quicken your product's arrival to market.

Data Analysis, Interpretation, and Quality Control

Our analytical experts go beyond simply providing raw data. Our experienced team offers thorough analysis and interpretation to help you understand the significance of test results for your specific application and industry. We also adhere to strict quality control procedures to ensure the accuracy and reliability of all our testing services.

Advanced Topics in Composite Testing

As the field of composite materials continues to advance, so do the testing methodologies. Smither stays at the forefront of these developments, offering expertise in areas such as:

• Fracture mechanics testing
• Creep and stress rupture testing
• Testing of nanocomposites
• Standardization development

Smither is committed to investing in the latest technologies and expanding our expertise to meet your evolving needs. Our labs are ISO 17025:2017 accredited (and/or calibrated) for thermoplastics and rototics composites testing, demonstrating Smither' unwavering commitment to upholding the highest testing standards.