A NEW UNIVERSAL FATIGUE MACHINE FOR PLASTICS AND COMPOSITES

摘要

Polymers and composites are more and more involved as structural parts in industry, and so to help the designer we need specific data such as long term mechanical properties (creep, relaxation, fatigue). In this paper we present the fatigue test, by which we study the behavior under repeated loading. The failure process in fatigue can be always depicted as a sequence of two steps: (1) Crack initiation (2) Crack propagation A number of investigations were carried out on the crack propagation step, ignoring the initiation step, by working on precracked samples. This necessitates specialized equipment, methodologies and analysis. This paper is more devoted to 'endurance behavior', which is the result of the two previous mechanisms (initiation first and then propagation). After a short presentation of the specific definitions and means of fatigue testing, we present a new universal fatigue testing machine, on which we can run any kind of test under different conditions (temperature, environment, frequency, stress or strain control, alternate or ondulate bending, torsion, tensile, etc.). [References: 21]