Fatigue life testing: Optical strain gages allow for up to 10 million load cycles at ±5,000 µm/m

Fatigue life tests at high strains make extreme demands on the test equipment used. Here, conventional electrical strain gages soon reach their limits.

The latest generation of optical strain gages provides the optimal solution in these cases. HBM's K-OP strain gages reach 10 million stress cycles in continuous vibration behavior with alternating strain of ±5,000 µm/m. The optical strain gages are also suitable for measurements in potentially explosive atmospheres and on components for high current and high voltage engineering.

The huge performance of HBM's optical strain gages has been confirmed through intensive testing at an independent institution.

Another benefit: Upgrading to optical strain gages is very easy for users of the classical, electrical types. The patented design of HBM's optical strain gages protects the glass fiber and ensures increased convenience and ease of installation during the test setup.

A further advantage of optical strain gages: Multiple sensors can be used in one glass fiber. This significantly reduces the outlay during installation. In addition, a data sheet is provided with the optical strain gages; it contains all data necessary for the strain measurements, such as the gage factor.

Recording of the measurement data and subsequent evaluation are also very simple. HBM offers the user all necessary components from one source. These range from optical strain gages with the appropriate accessories through interrogators and catman®AP data acquisition software, which includes a special EasyOptics module for optical strain gages.

Fatigue life

Fatigue life testing

If a strain gage is subjected to an alternating strain which can be superimposed over a static mean strain, an increase in the number of load cycles may create changes with regard to the zero point. The fatigue life is dependent upon the number of strain cycles and their amplitude and is independent of applied strain duration.