Tensile Testing

Owned by Hamza Abuabah
Last updated: Jul 20, 2019

The properties of the composite material we have needs to be determined, and several properties can be taken from the vendor, but there are many more that depend on the method of preparation and the specific conditions of the manufacturing method. Actually, there are just a lot of factors, the standard for tensile testing lists the following as possible factors that change tensile properties:

material, methods of material
preparation and lay-up, specimen stacking sequence, specimen
preparation, specimen conditioning, environment of testing,
specimen alignment and gripping, speed of testing, time at
temperature, void content, and volume percent reinforcement.


So material testing needs to be done for the batch being used to ensure it can meet requirements, and to properly simulate the composite in ANSYS ACP(Pre). Tensile tests are the most useful, and they obtain the most critical properties of a composite

Properties Obtained from a Tensile Test

  • EL - Longitudinal modulus of the composite
  • ET - Transverse modulus of the composite
  • σLU - Ultimate longitudinal modulus of the composite
  • σTU - Ultimate transverse modulus of the composite
  • ε - Ultimate tensile strain of the composite
  • vL - Poissons Ratio in the longitudinal direction of the composite


Specimen Design

The specimen used will be a dogbone shaped specimen, and it will be made with 8-16 plies. It should have a length of ~150mm. The ends need to be manufactured of different materials to avoid failure modes from the force coming from the grippers. This 

Specimen Manufacturing Procedure


Test Preparation Procedure


Notes on Measurement Equipment

  • The accuracy of instruments used for measurement shall be suitable to reading within 1% of the dimension. For example, a thickness needs to be measured with an instrument capable of reading with an accuracy of +-0.0025mm, if we have a 0.25mm thick sample
  • The tensile testing machine will need to be driven at a constant velocity, so it requires equipment, either built in or external, to be able to rotate the dial of the tensile tester to spin it at a constant speed. Something that can be used to control the tester is a drill. Controlling by hand is questionable.
  • Ask a technician/ lab instructor that is familiar with the machine if it is capable of measuring with precision in low and high load applications If the sample is being testing for UTS, much higher loads will be seen by the load cell, and the equipment may have to be calibrated differently. This means that the test for determining the modulus and the test for determining the strength may have to be performed separately to obtain precise results. The aim is to obtain force readings within +-1% of the value read on the dial throughout the entire range of the tensile test. 
  • Check what kind of gripper is available before building the specimen to designed the tabs appropriately


Testing Procedure