Combined axial and torsion testing

Citation

(2002), "Combined axial and torsion testing", Aircraft Engineering and Aerospace Technology, Vol. 74 No. 6. https://doi.org/10.1108/aeat.2002.12774fad.002

Combined axial and torsion testing

Combined axial and torsion testing

Keywords: Torsion, Testing, Zwick Roell group

Zwick Roell group informs us that axial and torsion testing can be carried out in combination or separately on its new testing machine (Plate 2).

Thought to be the first with this cost-saving dual capability, the digitally controlled system is said to be ideal for testing any materials or components that flex in different directions under load.

Incorporating a torsion actuator in the upper crosshead, the two-column machine employs load cells for force measurement. It is available in tabletop and floor-mounted versions with force ratings from 20 to 250 kN and torsion ratings from 100 to 2000 Nm.

Through Zwick’s dedicated “ItestXpert” testing software, the system can be set up on either the tensile/compression axis or the torsion axis for constant holding, constant cycling or stepped loading.

These selections enable a variety of testing combinations to be achieved. They include constant load with torsion testing, constant travel with torsion testing, constant torque with tensile/compression testing, constant torque angle with tensile/compression testing, and superimposed tensile/compression and torque testing.

The system can also be used purely in either tensile/compression or torsion mode, with one of the axes idle.

Additionally, the versatility of the Zwick software is said to allow various synchronous interactions between the test axes, ranging from no synchronisation at all to full event-controlled synchronisation.

Zwick also reports the development of a testing machine to establish the true performance of compression springs, believed to be the first of its kind.

A new six-channel digital system from the company is said to solve the problem of catering for the transverse forces that frequently lead to uneven loading at the spring ends. Simple testing cannot reveal a transverse load or its direction because the line of the force seldom follows the geometric axis of the spring.

In the new Zwick machine, forces are measured by six load cells placed vertically and horizontally under a heavy compression plate. The positioning of the load cells creates a three-dimensional coordinate system.

During spring testing, vertical and horizontal forces applied to the compression plate are transferred to the load cells by flexure-elastic double-crossed linkages. These are said to ensure that only tensile and compression forces reach the load cells, not transverse or torque.

From the six measurements, the vertical and horizontal forces and their distances from the machine axis are calculated by Zwick’s “testxpert” testing software, enabling the true scale and position of the spring’s reaction to be determined.

During the measurement cycle, the software acquires the six forces and spring lengths in synchronous time, storing and evaluating the values, which are displayed on a monitor.

As well as automatic testing, the machine can be used for manual spring testing under remote control with the results shown on the monitor.

Details available from: Zwick Testing Machines Ltd, Tel: +44 (0) 1568 615201.

Plate 2 The Zwick Zozo