Areas of application for strain gages

During experimental stress analysis, mechanical stress is determined based on strains measured on the component surface with known material properties (modulus of elasticity, transverse strain index). Often both the magnitude and direction of the primary stresses are of interest.

SGs in transducer construction

The deformation of a spring element caused by a load is recorded in the transducer construction by means of a strain gage (SG). This load can be a mass, force, torque or pressure. The measurement range of a load cell can extend from a few (kilo)grams to several hundred metric tons. This is independent of the mechanical rigidity of the transducer (spring element) but not the SG. The range is designed so that a (nominal) strain of about 1000 µm/m occurs at nominal load. An excellent signal-to-noise ratio is achieved in this manner and there is a sufficiently large safety distance to mechanical overload of the spring element.

SG for experimental examinations

Experimental stress analysis

During experimental stress analysis, mechanical stress is determined based on strains measured on the component surface with known material properties (modulus of elasticity, transverse strain index). Often both the magnitude and direction of the primary stresses are of interest. The term mechanical stress refers to a force acting on an area. These measurements are frequently used to verify the correctness of mathematical draft models (for example the finite elements method).

Internal stress analysis

Internal stresses are mechanical stresses inside a component arising without the action of any external forces or moments – for example because of the cooling process of cast parts, etc. Determining internal stresses on the surface of a component by means of installed SGs requires interfering with the stress state, for example by introducing a borehole (borehole procedure) or by cutting a ring groove (ring core method).

Durability test, weak point analysis, load analysis

The concepts alone reflect the wide range of corresponding application areas for SGs. Numerous components and objects are subject to examination – from automotive components through bearing surfaces to forming presses.

Determining thermal stresses

If free thermal expansion of a component is hindered, either partially or completely, thermal stresses arise in the material due to the change in temperature. Thermal stresses also originate from numerous temperature gradients, for example heating up and cooling off processes that affect one side only.

Files:

 Areas of application (72 kB)