Framework for Strain Measurements at Cyclic Loaded Structures with Planar Elastoresistive Sensors Applying Electrical Impedance Tomography

In the field of Structural Health Monitoring (SHM), strain is an often-used parameter for the evaluation of the structural integrity. A rather new approach to efficiently monitor the global strain field of a mechanical structure is to employ planar elastoresistive sensors as surface coating in combination with Electrical Impedance Tomography (EIT). Furthermore, the EIT approach simultaneously allows the monitoring for damages of the sensor area. The aim of this experimental research is the evaluation of homogeneous strain states under cyclic loading using planar elastoresistive sensors applying EIT. The purpose is to develop an experimental framework that involves various methods for strain evaluation (e.g., EIT, Montgomery method, strain gauge) in order to have a suitable test setup for new EIT evaluation methods and sensor material properties (e.g., set-in effect) including long-term behavior. In the future, this framework shall allow the investigation and improvement of EIT reconstruction for non-static loaded structures. In the present study, the considered specimen is a cyclic loaded tensile test coupon. For this first investigation, static load steps discretize the cyclic loading. Additional strain measurement methods, such as a traditional strain gauge, are applied for validation.