Acoustics

Dynamic- mechanical thermo analysis

A Gabo Eplexor 500N dynamic- mechanical thermo analyzer is available for measuring the frequency and temperature dependent stiffness, Young's and shear modulus of materials or small components.
The systems uses a forced non-resonant method as decribed by ISO 6721 Part 4 and 6.
A sketch of its composition is shown below.
The sample is hold by one of the sample holders for compression, tension, shear or three-point bending depicted on the right.
A motor together with a lifting gear induces a maximum pre-stress of 1500 N.
The upper part of the assembly is clamped and a sinoidal force of up to 500 N, within the frequency range of 0 -100 Hz, is apllied by the electrodynamic shaker.
The sample's deformation is detected by a displacement transducer and the stiffness of the sample / component is calculated.
Young's and shear modulus follow from the sample's dimensions.

The unit has a liquid nitrogen cooling and a heating system to operate within a temperature range of -150 to 500 °C.

Due to force transducer from 10 to 1500 N being available both very soft materials like foams used for acoustic absorption as well as stiff materials such as fibre reinforced plastics can be tested.

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Examples

Two examples of measurements done with the analyzer are shown below. First, the radial stiffness of a LORD AM001-10 low profile avionics mount is measured as a function of frequency.
A preload of 3 N and a dynamic force of 30 N were used. Measurements were done at room temperature.
As shall be expected for a visco-elastic material (silicone rubber), the stiffness increases significantly with increasing frequency.



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Another example is determining the Young's modulus of a carbon fibre reinforced plastics (CFRP) sample as a function of both temperature and frequency:
within the given measurement range, the properties do not vary much with these parameters. 

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