Extensometry and experimental stress analysis
Extensometry is a widely used measurement technique for experimental stress diagnosis (Experimental Stress Analysis) in components and structures subjected to real or simulated loads.
Strain gauge measurements make it possible to quantify mechanical deformations through sensors that transform dimensional changes into interpretable electrical signals, constituting a fundamental tool for validating numerical models, verifying finite element calculations and analyzing performance under real operating conditions.
Principle of operation of strain gauges
A strain gauge is an electrical resistance strain sensor consisting of a metal grid firmly affixed to a polymer substrate: as the surface of the deformed material stretches or compresses, the electrical resistance of the sensor varies in proportion to the strain. This variation, detected through a measuring circuit (such as a Wheatstone bridge), is the basis for calculating strain and, through established mechanical relationships, related stresses.
Experimental stress analysis focuses primarily on strain measurements on the accessible surface of the component under test: from these data it is possible to infer the local stress state, which is extraordinarily useful for verifying the safety and performance of structures under static or dynamic loading.
Why experimental stress analysis is important
Experimental stress analysis, conducted using strain gauge and strain gauge techniques, is an essential tool for measuring real strains and stresses on components and structures under load. Numerical models and FEM simulations provide a theoretical prediction of mechanical behavior; strain gauge measurements, on the other hand, allow these models to be validated with objective data obtained directly on the component under test.
Strain measurement (strain) allows the local stress state to be determined and any stress concentrations not anticipated in the design phase to be identified. This approach is critical for:
- Validate structural sizing;
- Check static or dynamic loading conditions in operation;
- Analyze fatigue phenomena;
- Support failure analysis activities;
- Correlate experimental data with stress analysis simulations.
Extensometry is therefore a key step in design validation and structural verification processes, especially when component reliability is a non-negotiable technical requirement.
Verify the behavior of your material with strain gauge techniques
What do we measure with strain gauge techniques in TEC Eurolab?
With the extensometry techniques applied by TEC Eurolab, it is possible to measure accurately:
- Deformation (strain) on surfaces and components
- Torque and strength
- Stress and equivalent stress
- Moving
- Temperature and pressure (through specialized strain gauges)
- Residual stresses generated by manufacturing processes or residual loads
The method is valid on metallic, plastic and composite materials and is compatible with both laboratory and field tests.
Post-processing and Data Analysis
- Vibration
- Acceleration
- Acoustic measurements
- Flow
- Angular Tilt
- Deformation measurements on PCBs
In what areas does extensometry apply
Strain gauge measurement and experimental mechanical stress analysis techniques find application in all areas where precise knowledge of the strain and stress state of a real component is needed.
Major areas of application include:
- Aeronautics and space: structural validation of critical components, FEM correlation, and qualification test campaigns.
- Automotive and motorsport: strain and stress measurements on chassis, suspension, mechanical parts and components subjected to cyclic loads.
- Energy and oil & gas: stress testing of pipelines, structures and pressure components.
- Manufacturing industry and automatic machines: validation of welded structures, frames, and kinematics.
- Biomedical: mechanical testing of devices and components where local deformation is critical to functionality.
In these contexts, the use of strain gauges makes it possible to obtain direct strain and stress measurements, which are essential for making technical decisions based on experimental data and not solely on computational assumptions.