Identification of the Mechanical Behaviour of Polymers thanks to Instrumented Indentation Tests

Since Brinell invented the hardness test around 1900, using a hard steel ball as an indenter and measuring the size of the residual indentation on a steel plate, the application of this test has diversified considerably: use of diamond pyramids (Vickers, Knoop and Berkovich) and WC-Co cobalt-bonded tungsten carbide balls, development of micro-hardness and nano-indentation machines, measurement of the force curve, etc. P-displacement during penetration phases h of the indentor increases, then decreases (instrumented indentation test). These tests are performed on most materials: metal alloys, ceramics and polymers. Previous articles (see below) have presented the mechanical interpretation of hardness testing, mainly in the case of metal alloys, while specifying certain points relating to ceramics. Polymers are increasingly used as coatings in the automotive, mechanical and optical industries, and instrumented indentation tests are often the only way to characterize their mechanical properties. The aim of this article is first to present the main characteristics of the mechanical behavior of polymers, and then to show how they can be determined from the results of instrumented indentation tests.

This article is the last in a series of five, the previous four being :

• body hardness and qualitative analysis [M 4 154]  ;

• hardness of common metals. Rigid-plastic limit case [M 4 155]  ;

• material hardness. Influence of elasticity [M 4 156]  ;

• hardness of bodies. Analysis of other behaviors