Coefficient of Linear Thermal Expansion (CLTE) - ISO 11359-1,-2
The change in length per unit length of a material per degree of temperature change.
CLTE is measured using a thermomechanical analyzer. The specimen is held in an enclosure and is contacted by a probe leading to a displacement sensor. A small force is applied to the specimen to keep the probe in contact with the specimen.
Thermomechanical Analyzer Setup
The enclosure is brought to a starting temperature. The temperature within the enclosure is increased at a uniform rate. The expansion of the specimen is measured by the displacement sensor over the temperature range of interest.
CLTE (α) is calculated using the formula:
α = ΔL / (Lo * ΔT)
where ΔL is the change in length of the specimen,
Lo is the original length of the specimen,
and ΔT is the temperature change during the test.
ISO 10350 Note
ISO 10350 specifies that the test temperature range is to be from 23°C to 55°C.