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Lecture

WEB Characterization of Geometric Deviations in Clinch Points with Computed Tomography and Transient Dynamic Analysis

Tuesday (22.09.2020)
15:55 - 16:10 Z: Special Symposia II
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In the last decade, lightweight structures gained much attention in the field of sustainable manufacturing. In the lightweight design, clinching is a cost-efficient solution for joining parts, especially if the joining parts’ materials and thicknesses deviate. The quality of such a joint can decline by deviations concerning bottom thickness, neck thickness and undercut. Furthermore, the geometrical properties of the clinch point are unsymmetrical if there are deviations concerning the coaxialty between the punch indention and the outer contour formed by the die. Ex-situ destructive testing methods usually determine such deviations. These methods, however, do not yield the detection of phenomena occurring during the joining process, such as elastic deformations and cracks that close after unloading. Moreover, in a production line, these methods recognize a quality deviation only after time and cost-intensive experiments. Monitoring the force progression of the joining process is a quick method to assess the joining process quality but not the joint. Therefore, this method does not provide sufficient information to characterize the deviations of geometrical characteristics. To overcome these limits, an in-situ characterization method will be developed using computed tomography (in-situ CT) and the transient dynamic analysis method (TDA), which investigates the manufacturing of the clinch point at certain process steps. When mechanical characteristics of a clinch point change, its dynamic behavior alters. TDA utilizes these changes by evaluating the energy transmission to detect and characterize geometrical changes. This work aims at creating a knowledge base to relate the deviations in the geometrical characteristics of the clinched joint to the response of the energy transmission of the joint. Hence, test specimens with bottom thicknesses deviating in three particular values are investigated with TDA and CT. On the one hand, the TDA of a simulated clinch point is conducted numerically to study the effect of the geometrical deviations on the transmitted energy. On the other hand, the geometrical deviations of the test specimens are measured experimentally and ex-situ using CT. The CT-characterization is supported by using radiopaque materials to detect the parting line between the join materials. Finally, the CT-measured deviations are linked with the simulated clinch point and the TDA results.

Speaker:
Additional Authors:
  • Behdad Sadeghian
    Technische Universität Dresden
  • Dr. Robert Kupfer
    Technische Universität Dresden
  • Prof. Dr. Maik Gude
    Technische Universität Dresden
  • Prof. Dr. Alexander Brosius
    Technische Universität Dresden