Eventos Anais de eventos
COBEM 2021
26th International Congress of Mechanical Engineering
EFFICIENCY ESTIMATION OF A CAPACITIVE DISCHARGE WELDING PROCESS IN THERMOCOUPLES
Submission Author:
Sandro Metrevelle Marcondes de Lima e Silva , MG , Brazil
Co-Authors:
Fábio Silva Faria, Rodrigo Gustavo Dourado da Silva, Bruno de Campos Salles Anselmo, Sandro Metrevelle Marcondes de Lima e Silva
Presenter: Fábio Silva Faria
doi://10.26678/ABCM.COBEM2021.COB2021-0941
Abstract
Determining the thermal input of a welding process is essential to improve the quality of the procedure. With the knowledge of the exact amount of heat used in the process, it is possible to control the equipment so that there is no excess or lack of energy. When there is an excess of energy in the process, the material can deteriorate or oxidize, losing its mechanical properties. The presence of oxidation also affects mechanical properties, which may lead to a rupture of the thermocouple during measurement applications. On the other hand, if there is a lack of energy, the junction of the materials becomes weak and can crack. In this work, inverse problem techniques are used to model and estimate the transient heat rate provided to a welding process accomplished by a capacitive discharge, in K-type thermocouple. An inverse heat conduction problem (IHCP) is that in which the boundary conditions or input parameters of the problem are unknown. To solve it, information of temperatures measured experimentally over time at some accessible point in the domain is used. Since the welding process under study is fast, obtaining temperature data in the regions of interest is tough. In addition, measuring the heat flux in the melt pool using a heat flux transducer, for example, would also be difficult. For this reason, it is essential to apply inverse heat transfer analysis, which can assess unknown or difficult-to-measure parameters. This experimental investigation of thermal effects is carried out using the software COMSOL® and the Specification Function Method (SFSM), which sequentially computes the heat flux at each time interval. To solve the IHCP in order to estimate the heat flux history, the SFSM searches for a heat flux that minimizes an objective function, which compares the temperature measurements taken close to the welding region with the numerical solution. Moreover, the efficiency of the welding process is also evaluated once the total energy employed is known by calculating the energy stored in the capacitor bank. The technique used to estimate the input power was efficient when compared with experimental temperature data.
Keywords
heat conduction, Inverse problem, welding process, capacitive discharge, Optimization
