Mts Series 609 Alignment Fixture Bedienungsanleitung PDF herunterladen (Seite 15)

Misalignment

Series 609 Alignment Fixture Product Information Introduction

Misalignment

In uniaxial testing, perfectly aligned grips produce uniform axial tensile strains in

a specimen. For grips to be perfectly aligned, their loading axes must be

concentric.

Perfectly Aligned Grips Produce Uniform Axial Strains

Misalignment between the grips produces nonuniform axial strains in a

specimen. Some areas will have higher than average strains; other areas lower

than average strains. Bending strain is the difference between the average strain

and areas with higher or lower than average strains.

Many ASTM procedures limit maximum bending strains because they cause

specimens to exhibit much lower strengths than if all axial strains were uniform.

The alignment fixture lets you reduce bending strains by improving concentric

and angular alignment between the upper and lower grips.

Grips can have concentric and angular misalignments. Both can occur together

and have a combined effect on the bending strains that appear in the specimen.

About Concentric Misalignment

Concentric misalignment shifts the vertical axes of the grips laterally away from

each other. This puts an “S” shaped bend in the specimen.

A specimen with an “S” bend has a zero bending strain in the middle of its gage

section. It has higher than average bending strains at the top and bottom of its

Mounting Surface

Equal Strain Equal Strain

Loading Axis

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Mts Series 609 Alignment Fixture Bedienungsanleitung Seite 15