ABSTRACT
Experimental procedures for viscoelastic materials, as in other experiments in mechanics, make use of a method for applying force or torque; a method for measuring the same; and a method for determining displacement, strain, or angular displacement of a portion of the specimen. This chapter discusses the methods for measurement and for load application separately, since many investigators choose to assemble their own equipment from components. Uniform stress is advantageous if the investigator has any interest in examining nonlinear response. Experiments performed in torsion or bending present some complications for nonlinear materials since the strain distribution is not uniform. Viscoelastic properties depend on temperature; therefore, some form of temperature control is usually used in viscoelastic measurements. Anisotropic materials have different stiffnesses in different directions. Transient experiments were conducted using an electronic servo-controller. Strain gages respond to strain from thermal effects as well as strain resulting from stress.
