Axial-torsion test

Two-in. multiaxial (axial/torsional/intemal pressure) composite tube test method [43]... 

The torsion test is generally considered to be the most accurate shear test and Figure 17.45 shows a thin walled tube subject to axial tension, which gives a state of pure shear and produces reliable measurements for both strength and modulus, but it is costly procedure. 

Figure 17.45 Tube subjected to axial torsion. Source Reprinted from Course on Mechanical Testing of Advanced Fibre Composites, University of London, Imperial College, Sep 1995.

E2207-15 Standard Practice for Strain-Controlled Axial-Torsional Fatigue Testing With Thin-Walled Tubular Specimens... 

The classic way that we perform force versus deformation measurements is to deform a sample at a constant rate, while we record the force induced within it. We normally carry out such tests in one of three configurations tensile, compressive, or flexural, which are illustrated in Fig. 8.1. We can also test samples in torsion or in a combination of two or more loading configurations. For the sake of simplicity, most tests are uni-axial in nature, but we can employ bi-axial or multi-axial modes when needed,... 

Dynamic mechanical analyzers are normally built to apply the stress or strain in three ways (Fig. 1). One can apply force in a twisting motion so one is testing the sample in torsion. Axial analyzers are normally designed for solid and semisolid materials, and apply... 

Cezayirlioglu et al [32] tested human bone under combined axial and torsional loading. The results are too complex to tabulate, but should be consulted by readers interested in complex loading phenomena. 

For this test, the fabric is subjected to cyclic torsion and axial efforts, similar to what is routinely practiced by healthcare staff (Fig. 6.3). The number of particles released from the fabric are measured in the same manner as the cleanliness test However, a linting test measures the particle reserve in the product for a longer term. The result typically reports as the coefficient of linting in Log(lO) values and calculates for the particle sizes of 3-25 pm. 

Most rheological measurements measure quantities associated with simple shear shear viscosity, primary and secondary normal stress differences. There are several test geometries and deformation modes, e.g. parallel-plate simple shear, torsion between parallel plates, torsion between a cone and a plate, rotation between two coaxial cylinders (Couette flow), and axial flow through a capillary (Poiseuille flow). The viscosity can be obtained by simultaneous measurement of the angular velocity of the plate (cylinder, cone) and the torque. The measurements can be carried out at different shear rates under steady-state conditions. A transient experiment is another option from which both y q and ]° can be obtained from creep data (constant stress) or stress relaxation experiment which is often measured after cessation of the steady-state flow (Fig. 6.10). 

Adams and Coppendale (1976, 1977) used a dynamic technique, for the axial butt joint, using the adhesive layer as a spring in an axially vibrating system. By comparing the frequency reduction when having an adhesive layer instead of a solid bar, they were able to calculate E, the effective Young s modulus. They then tested the same bars in torsional oscillation and obtained the shear modulus G by the same frequency change technique. From E and G, it is possible to calculate Poisson s ratio v, and hence to obtain E. 

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