Fracture in Axial Compression Tests of Cylinders

Failure modes are described for compressed cylindrical specimens of several aluminum alloys, 4340 steel of various tempers, several tungsten alloys, and textured titanium alloy Ti-4Al-4V. One common feature of failure among all the materials is that shear cracks are the first to initiate. For a number of materials, results for length-to-diameter ratios L/D = 1 and L/D = 2 are compared. Inferences of the stress-strain conditions for crack initiation have been made in a few cases from theoretical results obtained from a quasistatic version of the HEMP computer code.

Experimental results in the form of stress-end shortening curves, specimen photographs, and metallographic results are presented. From the experimental observations and HEMP code results a simplified phenomenological description of the failure process in some of the materials has been developed. However, a general theory of compression failure has not yet been deduced. Inferences of the limitations of procedures described in ASTM Compression Testing of Metallic Materials at Room Temperature (E 9) for obtaining a valid stress-strain curve have also been made.