The Testing Times

This is a 300 kN Self Aligning fitting designed for Tension testing applications only. It has an M36 lower and an M42 Upper bolt - to fit to the machine. The fitting to fitting to which you would attach the grips is M36. It meets the requirements of ASTM E8 Standard test method for tension testing metallic materials. It may also be used when working to ASTM E21-03a Elevated temperature tension tests.

It's sometimes necessary to attach a grip or fitting that has no way of self aligning , in these cases we've developed several ingenious ways to add this function to the machines. One of these methods is to use a Self- Aligning Fixture like the one shown in the picture. As it is designed to fit a 150 kN U-Series machine it is somewhat massive. The top thread being 1" UNF in diameter and the bottom an M33. It weighs, a not insignificant , 7kg; has a 110mm body diameter and is nearly a foot tall. The central pin that you can see has is supported by a Nitrile block which allows it to float, whilst absorbing the shock of a sample failure.

As mentioned before, we do a wide range of platens (two parallel plates that are used to compress the test specimen...) Often the sample is uneven or has protruding features, the fixed platens are less effectual in this instance. In cases like this, self aligning platens distribute the load across the sample by increasing the contact area. (The arrows show movement...)

This grip is designed to meet the very strict guidelines set within the ASTM D143 standard. I have mentioned this standard before, it is one of the most demanding standards available for wood specimens. One of the most important tests when it comes to the structure of wood is how it reacts in tension. As wood can be very strong in tension it's is necessary to 'profile' the sample (cut the wood into a specific shape) so that the region undergoing test is uniform, in the middle and weaker than the grip or piece of wood the grip is holding onto. It also needs to be smaller to allow an extensometer to be added to measure the small changes in the length of the sample. This grip is essentially self-aligning, the sample slotting into the two fingers.