CFRP 3-Point Bending Impact Test (Reference Standards: JIS K 7084:1993)

In recent years, carbon fiber reinforced plastics (CFRPs) have gained attention as strong, lightweight materials. To date, CFRPs utilizing thermosetting resins, which are not ideal in terms of cost, productivity, or potential for recycling, have been mainstream. As a result, they have been rarely used in transport vehicles except for aircraft. However, in the last few years, technology related to CFRPs utilizing thermoplastic resins has improved remarkably, so progress is being made in alleviating the above-mentioned disadvantages. In future, it is likely that CFRPs will be used in mass-produced vehicles, which will necessitate evaluations of the material. JIS K 7084 provides standards for testing machines in which a weight free-falls. In this experiment, we used the high-speed puncture impact testing machine, in which the speed is reduced only slightly on contact.

Measurements and Jigs

JIS K 7084 specifies the indenter radius as 5 mm, and the radius of each sample support as 2 mm. The test speed is 3.8 m/s. The standard dimensions of the sample are prescribed as follows.

Length (l) = 80 ± 1 mm
Width (b) = 10 ± 0.2 mm
Thickness (h) = 2 ± 0.2 mm

When tests are performed using a sample with the standard dimensions, the distance between supports (L) will be 60 ± 0.2 mm. JIS K 7084 specifies the test force sensor precision as ±5% of the test force value, and the sampling time as 10 μs max. This system satisfies the test force sensor precision for tests of 100 N or more. Sampling times of up to 1 μs are also possible.

Measurement Results