The investigation and reconciliation of the dynamic characteristics of a thin plate laser spot welded joint structure / Mohd Hakimi Othman

In the structural dynamic analysis, having accurate information on the dynamic characteristics of a structure is vital to help engineers or modal analysts to understand the structure's characteristics. The dynamic characteristics can be identified by the use of the finite element method (FEM) a...

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Main Author:	Othman, Mohd Hakimi
Format:	Thesis
Language:	English
Published:	2017
Subjects:	Lasers
Online Access:	https://ir.uitm.edu.my/id/eprint/67570/1/67570.pdf
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id	my-uitm-ir.67570
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spelling	my-uitm-ir.675702023-02-03T08:26:43Z The investigation and reconciliation of the dynamic characteristics of a thin plate laser spot welded joint structure / Mohd Hakimi Othman 2017 Othman, Mohd Hakimi Lasers In the structural dynamic analysis, having accurate information on the dynamic characteristics of a structure is vital to help engineers or modal analysts to understand the structure's characteristics. The dynamic characteristics can be identified by the use of the finite element method (FEM) and also by the experimental modal analysis (EMA). However, it is challenging for the modal analysts to reliably and accurately identify the dynamic characteristics of the structure merely using the finite element method, especially with the presence of mechanical joints such as spot welds, rivets, and bolted joints in the structure. The work presented in this thesis was primarily to investigate appropriate element connectors to be used for modelling and to reconcile the dynamic characteristics of a thin plate, laser spot welded structure via the finite element and model updating method. The initial finite element models of the welded structure were developed using three different element cpnnectors (RBE, ACM and CWELD) and the models were then used to predict the dynamic characteristics of the structure. Meanwhile, the measured dynamic characteristics were obtained using an impact hammer and roving accelerometers under free-free boundary conditions. The measured results were then employed in the updating method for reconciling the initial finite element model with the test structure. The largest total error of the discrepancy between the predicted and measured natural frequencies was recorded in the RBE based initial finite element model (47.61%) followed by ACM2 based initial finite element model (23.28%). The CWELD based initial finite element model with the smallest total error (22.66%) was found to be the most appropriate model to represent the thin plate laser spot welded structure and to then be used for model updating. The CWELD based initial finite element model was successfully reconciled to the test structure within a satisfactory, acceptable level of error. The results suggest that CWELD element connectors have a better capability to represent the laser spot welds in the structure in comparison with other element connectors. The improvement in the CWELD based initial finite element model reveals that the finite element model updating can be used successfully to reconcile the initial finite element model with appropriate modelling of the test structure. 2017 Thesis https://ir.uitm.edu.my/id/eprint/67570/ https://ir.uitm.edu.my/id/eprint/67570/1/67570.pdf text en public masters Universiti Teknologi MARA (UiTM) Faculty of Mechanical Engineering Abdul Rani, Muhamad Norhisham
institution	Universiti Teknologi MARA
collection	UiTM Institutional Repository
language	English
advisor	Abdul Rani, Muhamad Norhisham
topic	Lasers
spellingShingle	Lasers Othman, Mohd Hakimi The investigation and reconciliation of the dynamic characteristics of a thin plate laser spot welded joint structure / Mohd Hakimi Othman
description	In the structural dynamic analysis, having accurate information on the dynamic characteristics of a structure is vital to help engineers or modal analysts to understand the structure's characteristics. The dynamic characteristics can be identified by the use of the finite element method (FEM) and also by the experimental modal analysis (EMA). However, it is challenging for the modal analysts to reliably and accurately identify the dynamic characteristics of the structure merely using the finite element method, especially with the presence of mechanical joints such as spot welds, rivets, and bolted joints in the structure. The work presented in this thesis was primarily to investigate appropriate element connectors to be used for modelling and to reconcile the dynamic characteristics of a thin plate, laser spot welded structure via the finite element and model updating method. The initial finite element models of the welded structure were developed using three different element cpnnectors (RBE, ACM and CWELD) and the models were then used to predict the dynamic characteristics of the structure. Meanwhile, the measured dynamic characteristics were obtained using an impact hammer and roving accelerometers under free-free boundary conditions. The measured results were then employed in the updating method for reconciling the initial finite element model with the test structure. The largest total error of the discrepancy between the predicted and measured natural frequencies was recorded in the RBE based initial finite element model (47.61%) followed by ACM2 based initial finite element model (23.28%). The CWELD based initial finite element model with the smallest total error (22.66%) was found to be the most appropriate model to represent the thin plate laser spot welded structure and to then be used for model updating. The CWELD based initial finite element model was successfully reconciled to the test structure within a satisfactory, acceptable level of error. The results suggest that CWELD element connectors have a better capability to represent the laser spot welds in the structure in comparison with other element connectors. The improvement in the CWELD based initial finite element model reveals that the finite element model updating can be used successfully to reconcile the initial finite element model with appropriate modelling of the test structure.
format	Thesis
qualification_level	Master's degree
author	Othman, Mohd Hakimi
author_facet	Othman, Mohd Hakimi
author_sort	Othman, Mohd Hakimi
title	The investigation and reconciliation of the dynamic characteristics of a thin plate laser spot welded joint structure / Mohd Hakimi Othman
title_short	The investigation and reconciliation of the dynamic characteristics of a thin plate laser spot welded joint structure / Mohd Hakimi Othman
title_full	The investigation and reconciliation of the dynamic characteristics of a thin plate laser spot welded joint structure / Mohd Hakimi Othman
title_fullStr	The investigation and reconciliation of the dynamic characteristics of a thin plate laser spot welded joint structure / Mohd Hakimi Othman
title_full_unstemmed	The investigation and reconciliation of the dynamic characteristics of a thin plate laser spot welded joint structure / Mohd Hakimi Othman
title_sort	investigation and reconciliation of the dynamic characteristics of a thin plate laser spot welded joint structure / mohd hakimi othman
granting_institution	Universiti Teknologi MARA (UiTM)
granting_department	Faculty of Mechanical Engineering
publishDate	2017
url	https://ir.uitm.edu.my/id/eprint/67570/1/67570.pdf
_version_	1783735700606156800

The investigation and reconciliation of the dynamic characteristics of a thin plate laser spot welded joint structure / Mohd Hakimi Othman

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