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. When a strain gauge is subjected to excessively high strains outside its specifications resulting, for example, from alternating loads with superimposed static mean stress, the metal grid can be damaged with an increasing number of load cycles, resulting in failure of the strain gauge.

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. Suitable adhesives can also be obtained from HBM.

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.