ASTM D790 Flexural Properties of Unreinforced and Reinforced Plastics and Electrical Insulating Materials

Get Certified ASTM D790 Testing for Reliable Flexural Performance of Plastics

Plastic and composite materials are tested in accordance with ASTM D790 to determine their flexural properties under standardized laboratory conditions. Laboratory testing confirms the flexural strength, modulus of elasticity, strain characteristics, and bending performance under controlled testing conditions. Testing in accordance with ASTM D790 supports product development, quality assurance, material selection, and manufacturing consistency by providing standardized flexural property data. 

• Measures the flexural characteristics of unreinforced and reinforced plastics.
• Applies to electrical insulating materials and high modulus composite materials.
• Tests the flexural strength, flexural modulus, and flexural strain.
• Supports material qualification, quality assurance, and product development.
• Establishes common methods of comparing flexural properties of plastics.
• Can be used for rigid and semi-rigid plastics for engineering parts. 

ASTM D790 Testing Process and Data Collection

The first stage of the testing process is to prepare representative samples according to the dimension and conditioning requirements. The specimens are fixed in a three-point bending fixture in a universal testing machine and bent until they break or the desired strain is reached. The load, deflection, specimen dimensions, testing speed, support span, flexural stress, flexural strain, and modulus values are continuously captured and correlated to the applicable ASTM D790 requirements, resulting in standardized reporting and reliable material evaluation.  

What are the Uses of ASTM D790 Testing?

ASTM D790 tests are useful to manufacturers, engineers, and quality control laboratories to assess the flexural properties of plastics and composite materials for structural and industrial applications. The outcome helps in material selection, product development, quality assurance, and process validation in production. Here are the common applications – 

• ASTM D790 testing is used to measure the flexural strength and stiffness of plastic materials to help determine their suitability for engineering applications.
• The ASTM D790 test method is used by automotive manufacturers to assess plastic interior parts, structural panels, brackets, and composite parts that are bent. 
• To ensure the mechanical characteristics of composite materials and lightweight structural components when they are subjected to flexural loading, the aerospace industry conducts ASTM D790 testing. 
• ASTM D790 testing is used to assess composite decking, insulation material, structural panels, pipes, and plastic building products for construction material manufacturers. 

What materials can be tested with ASTM D790?

Various plastics and composites such as thermoplastics (PE, PP, ABS, PVC, etc.), thermosetting plastics (epoxies, polyesters, urethane, etc.), reinforced plastics, and fiber-reinforced plastics used in different industries (e.g., automotive, aerospace, construction, etc.) are tested in this test. 

Why is ASTM D790 Important for Flexural Testing?

ASTM D790 is a standard that outlines a test procedure for measuring the bending properties of plastic and composite materials in a controlled laboratory environment. Reliable flexural testing can help manufacturers to understand material stiffness, strength, and deformation characteristics, and can aid in product development, quality assurance, engineering design, and material selection. Standardized testing also enables comparisons between materials and manufacturing processes. 

Analysis Results and Interpretation

• ASTM D790 determines flexural properties using a three-point bending test in which a specimen is supported at two points and loaded at its midpoint until failure or until the specified strain limit is reached. The resulting load and deflection data are used to calculate flexural stress, flexural strain, and flexural modulus.
• Flexural performance is typically expressed in terms of flexural strength (MPa or psi), flexural modulus (GPa or MPa), and flexural strain (%).
• The test also measures tangent modulus, secant modulus, chord modulus, flexural offset yield strength, and flexural stress at break (where applicable).
• The flexural strength and flexural modulus are important factors for providing resistance to bending loads and structural stiffness, respectively, and their higher values are preferable.
• Test results are used in conjunction with specimen size, testing conditions, rate of strain, and environmental conditions to assess material performance.
• Measured flexural properties should be evaluated together with applicable design requirements and material specifications when determining suitability for engineering applications.

Link to ASTM D790