臺灣博碩士論文加值系統

產品衝擊實驗及模擬是電子產品發展中，常用來驗證機構設計良窳的方法之一，現今的3C產品設計中，部份的機構破壞，例如外殼破裂和內部機體剝離等，都發生在複次衝擊之後。因此， 模擬連續衝擊後之機械行為有其工程上的必要性，本論文主要目的為應用高階CAE軟體ABAQUS分析模擬3C產品的塑膠外殼在複次衝擊下之破壞行為，損壞與否之判斷基準為等效塑性應變值(Equivalent Plastic Strain value)，第一種實驗是以3kg重之Gardner落鎚自6， 8 及10英吋高度墜落連續衝擊塑膠外殼表面，再配合數值分析結果做比較.顯示在各個衝擊條件下，於複次衝擊時外殼將造成的破壞情形，實驗結果證明了模擬之準確性.第二種實驗稱之為鐘擺撞擊實驗，主要用來改善Gardner落鎚實驗的缺陷，去除不可控制之變數，其實驗方式為利用大型鐘擺撞擊測試機，經由能量守恆方程式計算，定義出三種不同鐘擺高度，進而實施衝擊.所得到的實驗結果再與數值分析作比較而得更準確之結果

Impact simulation has been an in-house practice to verify the mechanical design quality of products under development. However， mechanical failures such as housing cracks and part disengagement observed in in-house testing happen at subsequent impacts. There is a need to simulate multiple impacts to capture these events. The purpose of this paper is to perform the utility of using High-end CAE software “ABAQUS” to simulate the crack occurrence of 3C product plastic housing under multiple-impact. Equivalent Plastic Strain value is employed to be criteria judging if crack coming out. First experiment， the test condition is to release 3kg weight punch from 6， 8 and10 inch height to impact plastic housing surface with multiple times. Then check crack occurrences in plastic housing with simulation result. The experimental and simulation results agree well， proving the accuracy and the usefulness of the developed simulation strategies. Second experiment is called Pendulum impact test which is used to eliminate defect in Gardner impact test. The test process is we firstly calculate 3 kinds of heights belong to Pendulum tester which equals with 6， 8 and 10 inch in Gardner impact test. And then set them in the machine .To compare actual result with simulation as well. It demonstrate us the more accuracy outcome than Gardner test.

Table of content

摘要 i
Abstract ii
誌謝 iii
Table of content iv
The List of Tables vi
The List of Figures vii
Chapter1 Introduction 1
1.1 Motivation 1
1.2 Literature Review 2
1.3 Introduction of the experiment plan 5
1.4 Thesis Structure 6
Chapter2 Theoretical Analysis 7
2.1 Finite element method introduction 7
2.2 Introduction to CAE software “ABAQUS” 8
2.2.1 Analysis Modules 9
2.2.2 Pre-processing Module (ABAQUS/CAE) 10
2.2.3 Post-processing 11
2.2.4 ABAQUS User subroutines 11
2.2.5 ABAQUS Software Limitation 12
2.3 Euler Method 12
2.3.1 Forward & Backward Euler method 12
Chapter3 Technical Approach for Multiple Impact Simulation 16
3.1 Strategy 1: VUMAT Material Coding 16
3.1.1 VUMAT and Theory of Plasticity 17
3.1.2 VUMAT Material Coding Strategy 19
3.1.3 VUMAT Verification 20
3.2 Strategy 2: Use of PEEQ 24
3.2.1Yield/ Failure Criteria，Equivalent/Von Mises stress and Equivalent strain 25
3.3 Strengths and Limitations of both Strategies 27
3.4. Import/Export of Outputs 28
3.5. Garder Impact Test Results 29
3.6. Results and Discussion 31
Chapter4 Experimental Impact with Pendulum Test 35
4.1 Test Case Selection 35
4.2 Simulation Strategy and Assumptions and Limitations 36
4.3 Drop Impact Test 38
4.4 Experiment and Simulation Results，Correlations and Discussions 42
4.5 Experiment Summary 45
Chapter5 Conclusion 47
5.1 Conclusion 47
5.2 Study for future 47
References 49
Appendix 51
A Radial Return Algorithm for Classical J2 Flow Theory 51
Nomenclature 54

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