Measure of Shear and Compression Components of Puncture Tests

Abstract

SUMMARYA study was designed to separate and measure the compression components (proportional to area) and the shear components (proportional to perimeter) of a simple puncture test. Two sets of punches were used (one with a constant area and a variable perimeter, and the other with a constant perimeter and a variable area) to measure the compression and shear components in puncture tests on foam plastic board and representative foods. The puncture force for both can be expressed by the equation F = K,P + K,A + C, where K., K, and C are constants, P is the perimeter of the punch, and A is the area of the punch. K, represents the shear coefficient and Kc the compression coefficient of the food being tested. For a given punch, F depends upon K, and K, which are properties of the material being tested. For a given material, F depends on the perimeter and area of the punch. These results can be used as a basis for design of punch shape and size in a practical puncture test. The shear component of a puncture test can be increased or decreased relative to the compression component by manipulating the perimeter/ area ratio of the punch.