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One major ambition in Structural Health Monitoring (SHM) is to develop the ability to detect, identify and localize damage as well as to predict the lifespan of civil structures. This would allow well-informed decision on whether to repair or to demolish these structures. We want to focus on the issues of detection and localisation of damage caused by material degradation within a slender beam - a structure that is often used as a construction carrier.
The integration of finite element method (FEM) into the least-squares adjustment presented in [1] is further extended for a joint evaluation of an elastostatic model and displacement field measurement. For linear solids which obey the HOOKE's law, the material parameters determination from measurements is being examined. In many literature, see for example [2], parameters are iteratively tuned until the computed FEM results are in accordance with the measurements. In contrast to these debatable approaches, we follow a rigorous and direct method. The “classical” FEM procedure starts with known material constants and ends up with computed fields such as dis-placement or temperature field. We present a method to invert the FEM procedure using the most general least-squares adjustment – the GAUSS-HELMERT Model (GHM). From given fields, the material parameters are directly calculated.
The determination of material parameters from displacement field measurement is being examined for linear elastic solid. A frequently used approach to compute material constants can be found in many studies. Even though they presented the approach in many different variations, but in the end they are essentially based on the same algorithm: Parameters are iteratively tuned until the computed results are in accordance with the measurements. The main drawback of this approach is that mainly commercial software is used that hinders us to investigate its inner evaluation process. This leads to the question, how the results from this commercial software can be trusted. On the contrary to these debatable approaches, we present a method that inverts the procedure of finite element method by using the most general model for a least-squares adjustment – the GAUSS-HELMERT Model.
Many engineering structures are nowadays made of composite materials or metal foam. These modern engineering materials contain very complex inner geometry. To simulate the deformational behaviour of these structures often requires a high number of discretisation elements. This in turn yields a very large system of linear equations that are extremely time and memory consuming or practically impossible to solve. It is therefore desirable to find an approach to overcome this obstacle. In this paper a numerical method is proposed to find an approximate substitute model for geometrical complex structures.
The Measurement- and Model-based Structural Analysis (MeMoS) integrates a finite element model into least squares adjustment and thus allows to evaluate a mechanical model and measurements in a combined analysis. To examine the capability to detect and localise damage using this integrated analysis MeMoS, a small-scale truss bridge made of aluminium profiles is built as a test specimen for this purpose.