Equipment designed to test ceramics A range of equipment and accessories designed specifically for testing ceramic materials has been introduced by Instron Ltd of High Wycombe, UK.

Conventional testing equipment is said not to grip, bend or fatigue ceramic test pieces adequately due to the hardness and sensitivity of the materials. Specimens can fail prematurely through a small degree of misalignment or bending.

To reduce the risk of losing valuable specimens Instron has produced a range of dedicated equipment, from simple room- temperature bend testing to automated tension-compression cyclic fatigue equipment able to operate at 1500°C.

A specially aligned load frame and actuator form an integral part of one of the fatigue systems. A table-top hydrostatic bearing that keeps the actuator piston centrally located ensures high lateral stiffness. The frame is used with water-cooled hydraulic grips, a 1500°C in-air furnace

I nstron's 'advanced ceramic system' and a high temperature extensometer. Minimal bending, uniform test section temperature and high resolution strain measurement are claimed.

Contact: Ken Robinson, Instron Ltd, Coronation Road, High Wycombe, Bucks HP12 3SY, UK.

Improved version of potential drop crack monitor is introduced Shown here is the Pulsed DC Potential Drop Crack Monitor from Howden Machinery of Rugby, UK.

The instrument controls changes in crack length and determines the factors affecting the changes. Reliable and accurate data are produced according to Howden, the unit having been improved over the original model that was developed for use in aerospace applications.

Improvements include: a more compact size-power supply, amplifiers and readout facility are all housed in a 0.48 m rack mount case; errors due to thermoelectric effects and amplifier offsets are overcome by use of the

Baudin pulsed current technique; output voltage integrity is maintained through logic control for all fatigue frequencies and waveforms and static load conditions.

The photograph shows the instrument being used with an Amsler resonant fatigue testing machine, the Howden control package and a BBC microcomputer. For further details contact: Howden Machinery (Leamington Spa) Ltd, 41 Sorters Road Industrial Estate, New Bilton, Rugby, Warwickshire CV22 7DG, UK.

Fixture said to solve ceramic test problems A fixture for use in three- and four- point bend testing of ceramics and some stiff composites is said to solve the problems associated with contact stresses, specimen geometry and internal defects.

This is accomplished, according to the manufacturer, MTS of Minneapolis, MN, USA, through the use of roller bearings that rotate freely about the X and Y axes of both the loading and support members. The fixture can be used at high temperatures (540°C) and converts easily between the three- and four- point configurations. Potential drop crack monitor from Howden

UK firm fatigue tests artificial limb components More than 300 components of artificial limbs have been fatigue tested in the laboratories of Cape Environmental Engineering at Warwick, UK, on behalf of limb manufacturer J.E. Hanger & Co. These have been mainly for development purposes but have included random samples from the production line for quality assurance.

Testing is generally carried out in the range 1-20 Hz, and typically a load of 1350 N is applied at an offset of 103.7 mm to simulate the strain imposed by a walking action. The duration of each test is normally five million cycles, twice that required under UK government specifications. Another similar test programme contract has been awarded to Cape by limb manufacturer Vessa Ltd of Alton, UK.

Cape Environmental Engineering Ltd, Birmingham New Road, Warwick CV34 4TX, UK.

System automates CAD A computer-based system that automates the design and evaluation of mechanical and electronic systems has been announced by GenRad (UK) Ltd of Maidenhead.

The Integrated Test and Analysis System (ITAS) is targetted to link remote data acquisition stations to a host processing unit, and is claimed to be the only system of its kind that integrates computer-aided design and computer-aided product development.

Suitable areas of application range from the evaluation of road vehicles and components to electronic equipment support structures. Five systems have been sold to date, one to Ford Motor Company for its Dagenham, UK, site.

GenRad Ltd, Norreys Drive, Maidenhead, Berks SL6 4BP, UK.

L Ceramic testing fixture from MTS

MTS Systems Corporation, Box 24012, Minneapolis, MN 55424, USA.

248 Int J Fatigue October 1987