Rotating Fatigue Machine Mk3- Engineering Lab Training Systems
Model HV-EXP4860
Features Self contained Bench mounted Fully guarded Digital readout of revolutions to failure Motor stops when specimen fails Necked specimens, steel, aluminium alloy and brass Ideal introduction to fatigue Optional extra for alternating bending fatigue Three year warranty Range of Experiments To make an introductory study of fatigue using a Wohler rotating fatigue apparatus, including the time to failure caused by various stress levels and materials The accessory, HSM19X affords bending fatigue of a cantilevered strip of metal or plastic in modes varying from alternating to fluctuating stresses Description This machine has been designed to introduce students to the effects of fatigue. A simple cantilever specimen rotates at about 5700 or 1425 revs/min, inducing a sinusoidal variation of bending stress. At the faster speed, a third of a million stress reversals occur each hour, so failure should occur within a day. Failure can be hastened by using a specimen with a stress raiser. The loading system cancels its own self weight enabling any desired value of bending stress to be applied, ten mild steel specimens are supplied. Axiality has been ensured, and care has been taken to reduce the effects of vibration. When failure occurs, a microswitch stops the motor and the cycles to failure are registered on a 5 digit revolution counter. All rotating parts are shielded and a safety guard is provided to restrain the broken specimen. The apparatus is mounted on a heavy steel base plate and is designed to overhang the bench or pedestal on which it is placed. Ideally a heavy pedestal (eg concrete), isolated from the floor by rubber matting, should be used to minimise shock loads. An additional accessory for alternating bending fatigue and additional specimens are available. This equipment is part of a range designed to both demonstrate and experimentally confirm basic engineering principles. Great care has been given to each item so as to provide wide experimental scope without unduly complicating or compromising the design. Each piece of apparatus is self-contained and compact. Setting up time is minimal, and all measurements are made with the simplest possible instrumentation, so that the student involvement is purely with the engineering principles being taught. A complete instruction manual is provided describing the apparatus, its application, experimental procedure and typical test results..
