Design of a Split Hopkinson Bar Apparatus for use with Fiber Reinforced Composite Materials

Tabulated material properties are the starting block for the design of most structures. Mechanical structures undergo a wide range of loading conditions. Structures can be loaded statically or dynamically with a wide range of strain rates. With impact loading or high strain rates the relationships between stress and strain are not the same as in static loading. It has been observed that material properties are dependent upon the rate at which they are tested. Many investigators have studied the effect of high compressive strain rate loading conditions, in metals. The most common method for determining the dynamic response of materials is the Split Hopkinson bar. The main focus of this work was to design a Split Hopkinson Bar apparatus to determine the dynamic compressive behavior of fiber reinforced composite materials. Graphite epoxy laminated composites have compressive failure strengths of 100 MPa. Dynamic compressive testing shows that the failure stress has increased to 260 MPa, an increase of approximately 230%. This testing shows that material properties are a function of the rate at which they are loaded