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.
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.
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.