EXPERIMENTAL STUDY OF FIBER-REINFORCED PLASTICS IN A BROAD RANGE OF STRAIN RATES

The paper presents a review of testing fiber-reinforced plastics for strength and elasticity characteristics at high strain rates. Particular attention is paid to strain rate ranges covered, conformity of stress state to the expected one, and validity of failure mode. The review is presented in an “approach, configuration, method” paradigm, where the configuration means geometry of the specimen and auxiliary equipment, the approach is either to create a simple configuration with a complex stress state (non-classical approach), or a complex configuration providing a homogeneous stress state (classical approach). Finally, the method is a combination of configuration and test facilities. This narration logic allows us to systematize a large number of experimental methods and outline the ways of their further development. In addition, the paper presents original methods and results of the tests carried out by the authors. These methods add to a collection of experimental techniques and expand the range of strain rates covered. In particular, the strain rate range for tensile tests of unidirectional carbon fiber-reinforced plastics along fibers is significantly extended by applying the configuration of a wound ring specimen, in the methods of ring expansion (strain rates of the order of 5×102 s-1 are obtained) and exploding wire (strain rates of 1.5×104 s 1 are obtained). The range of strain rates for tension transverse to fibers was also extended by plate impact tests. In the experiment, strength values of 45 and 55 MPa were obtained for a tensile strain rate of 1.5×104 s 1, which is two and a half times higher than the strength in static experiments.