TABLE OF CONTENTS Tensile strength and tensile modulus measurements are among the most important indications of strength in a material and are the most widely specified properties of plastic materials. A tensile test is a measurement of the ability of a material to withstand forces that tend to pull it apart and to determine to what extent the material stretches before breaking. Tensile modulus is an indication of the relative stiffness of a material and can be determined from a stress-strain graph.
Different types of plastic materials are often compared based on tensile strength, elongation, and tensile modulus data. Many plastic materials are very sensitive to strain caused by force or load and environmental conditions. Therefore, the data obtained by this method cannot be considered valid for applications involving load time scales or environments widely different from the conditions used in the test. It is more useful to compare the tensile property data at several temperatures for plastic materials from a database, which is used in actual finite element method (FEM) computer analysis design of the part. This computer analysis program takes into account the time-dependent behavior of the part and the plastic materials under simulated loads at various temperatures.
Commercially available tensile testing equipment can test a single station, or up to five independent stations, stretching the tensile test bar at a constant rate with a cross-head movement. The machine has a fixed or essentially stationary member carrying one grip and a movable...
