Introduction
Even among composite materials, carbon fiber reinforced plastic (CFRP) has a particularly high specific strength, and is used in aeroplanes and some transport aircraft to improve fuel consumption by reducing weight. Compressive strength is an extremely important parameter in the design of composite materials that is always tested. However, due to the difficulty of testing compressive strength there is a variety of test methods. A major compression test method is the combined loading compression (CLC) method found in ASTM D6641. The CLC method can be performed with a simple jig structure, untabbed strip specimens, and can be used to simultaneously evaluate strength and measure elastic modulus. We performed compression testing of CFRP according to ASTM D6641.Measurement System
A CFRP specimen of T800S/3900 was used. Other information on the specimen is shown in Table 1. The test equipment used is shown in Table 2. Based on the CLC method in ASTM D6641, the specimen was attached to the jig shown in Fig. 1 and compressed using compression plate. Fig. 2 shows a photograph of the specimen. As shown in Fig. 2, a strain gauge was attached on the front and rear in the middle of the specimen. Outputs from the front and rear strain gauges confirmed that the specimen was aligned straight in the jig during specimen attachment. The specimen was attached using a torque wrench to fasten it in place uniformly. The test was performed with the test speed set to 1.3 mm/min.
Test Results
Measurements were performed twice, and stress-strain
curves are shown in Fig. 3. The strain used is the mean
strain taken from the front and rear sides of the
specimen. The relationship between the first strain
measurement and time is shown in Fig. 4 to show the
outputs obtained from the strain gauges. Fig. 4 shows
the outputs from both strain gauges were almost the
same up to around 40 seconds, which is evidence that
the test was successful. A small amount of deviation
between the strain gauges arises after around 0.5 %
strain, which is caused by a small amount of specimen
flexure. Table 3 shows the test results. The mean
compressive strength was 640.7 MPa, and the mean
elastic modulus was 72.9 GPa. Elastic modulus was
calculated using the mean of the strain gauge outputs.
English 
German 
Czech 
Slovak 
Bulgarian 
Romanian 