Mecmesin MultiTest-x manual
33
Pressing [2] will toggle between the Limit Type options available (‘ABS’ and
‘%TARG’). The option chosen will influence the parameters which will need to be
entered when setting the pass/fail analysis limits for each calculation (see [1], [3], [2],
[2] Set Limits, above),
• ‘ABS’ means that a tolerance band with upper and lower limit values can
be set-up, (i.e. between 18 and 22 newtons)
• ‘%TARG’ means that a tolerance band based upon a target value with
percentage limits can be set-up, (i.e. a target value of 20 newtons with a
percentage limit of ±10%)
[1], [4], [3] Stiffness Fact(or)
MultiTest-x systems measure specimen deformation under tensile or compressive
load by measuring crosshead movement. On occasions the deformation of the test
stand, loadcell and fixtures will not be trivial compared with the deformation of the
specimen. If the ‘stiffness’ of the test system is known, the software can accept a
value of stiffness factor and compensate for this potential error.
Note than if no stiffness factor has been entered a value of zero will be displayed; this
means that the software will treat the test stand, loadcell, and fixtures as being
infinitely stiff (i.e. the ‘compliance’ is zero), and no correction for deflection of the
system will be made.
The stiffness of a particular test system can be measured by driving the crosshead
down very slowly until the Xtra loadcell and attached fixturing make contact with the
anvil plate of the MultiTest-x. The apparent ‘specimen stiffness’ beyond the point of
contact will, because the anvil plate is infinitely stiff, be the stiffness of the test system.
Note that a test of this kind can potentially cause serious damage to the Xtra loadcell.
It is strongly recommended that before attempting any test of this kind all users should
discuss the matter with their local Mecmesin agent who will be pleased to give further
advice.
Should a different stiffness factor need to be entered (perhaps because another
loadcell and/or different fixtures are to be used), type in the appropriate value, in the
units indicated, and press the [Start/ENT] key to update.
[1], [4], [4] Procedure Name
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