武汉理工大学毕业设计（论文）

Finite Element Simulation Analysis for bulletproof of Armored Vehicle

学院（系）： 国际教育学院

专业班级： 车辆gj1603班

学生姓名： 刘晨希

指导教师： 汪舟

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作者签名：

2020 年 5 月 20 日

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作者签名： 2020年5月20日

导师签名： 年 月 日

Abstract

With the help of finite element analysis software Abaqus and based on its Explicit dynamic analysis function, this paper simulates the process of armor plate penetrating by 7.62mm bullet. This paper aims to study the influence of various factors on the protective performance of steel plates. In this study, three bullet models with the same specifications and different shapes, including pointed, round and flat head, were established. Two kinds of steel with Johnson-Cook parameters were selected. Weldox460E and Armox500T were used to establish armor plate models. Through numerical simulation, the visualization of the process of bullet penetrating armor plate is realized. By comparing the time-invasion velocity curve and the time-invasion volume curve of the bullet in the process of penetrating armor plate, the strength of the anti-elastic performance of armor plate is analyzed. This paper puts forward several experimental schemes and sets up several groups of control experiments to discuss the performance of armor steel's protective performance under the conditions of different bullet speeds, different bullet shapes, different bullet entry angles and different armor steel materials. In this paper, a new idea is put forward to improve the anti-elastic performance of armored vehicles. By analyzing the influence of residual stress on the anti-elastic performance of armored steel, the scheme of changing the anti-elastic performance of armored vehicles through stress processing is discussed.

Key Words：Abaqus/Explicit; Johnson-cook; Finite element simulation; Projectile penetration; Residual stress

Contents

1. Introduction 1

1.1 Background and Significance 1

1.2 Experimental Methods and Research Status 2

1.2.1 Experimental Methods 2

1.2.2 Research Status at Home and Abroad 3

1.3 Numerical Simulation Methods 6

1.4 The Work and Main Research Contents 7

2. Theoretical Basis and Model Establishment 9

2.1 Theoretical Basis 9

2.1.1 Protection Standard and Protection Grade 9

2.1.2 Quality Benefit Coefficient 10

2.1.3 Differential Benefit Factor 11

2.1.4 Risk Factor 11

2.1.5 Johnson-Cook Constitutive Model 11

2.1.6 Von Mises equivalent stress 12

2.2 Material Parameters 13

2.3 Model Establishment 14

3. Numerical Simulation of Bullet Penetration 17

3.1 Boundary Conditions Setting 17

3.2 Confirmation of Meshing Precision 17

3.3 Simulation of Different Steels 19

3.4 Numerical Simulation of Different Bullet Shapes 20

3.5 Numerical Simulation of Initial Conditions of Different Bullets Invasion 22

3.5.1 Numerical Simulation of Invasion Velocity of Different Bullets 22

3.5.2 Numerical Simulation at Different Driving Speed 23

3.5.3 Numerical Simulation with Different Bullet Invasion Angles 24

3.6 Numerical Simulation under Different Residual Stress Fields 25

4. Results and Discussion 27

4.1 Influence of Meshing Precision on Numerical Simulation of Projectile Penetration 27

4.2 Bulletproof Performance of Different Steels 27

4.3 Protective Performance of Armored Steel under Different Shaped Bullets Invasion 28

4.4 Influence of Bullet Invasion Speed on Protective Performance of Armored Steel 29

4.5 Influence of Bullet Entry Angle on Protective Performance of Armored Steel 30

4.6 Effect of Residual Stress Field on Protective Performance of Armored Steel 31

5. Summary and Prospect 33

References 35

Acknowledgement 39

1. Introduction

1.1 Background and Significance

The development of human history cannot be separated from the development of war, and the development of war cannot be separated from the development of armor. In ancient times, soldiers began to wear rattan armor to weaken the damage from the enemy. After the advent of metallurgical technology, metal armor was draped over soldiers to protect them from attacks from cold weapons. With the gradual progress of science and technology, hot weapons began to be put into war, bows and arrows were replaced by guns, and war horses were replaced by chariots. Facing all kinds of ammunition on the battlefield, bulletproof armor came into being. The requirements for bulletproof devices also range from the initial protection against threats such as stray bullets and fragments to protection against armor-piercing bullets and firebombs.

After the end of the Second World War, the world entered a short period of peace. The powerful countries took this opportunity to develop their military level on a large scale. Entering the 1980s, the international situation changed into overall peace and local conflicts continued. At this time, the gap between the military levels of various countries has widened, and the form of war has evolved into asymmetric warfare [1]. Combating terrorists and international peacekeeping have become the key tasks of military powers.

However, with the transformation of the objectives of modern warfare, the main battlefields have also changed from valleys and plains to cities and towns, and street warfare accounts for a large proportion in military operations. Although the traditional tracked armored vehicle has sufficient protection capability, its mass is too large to complete the task smoothly and timely in special battlefields due to its slight lack of mobility, flexibility and greatly reduced loading capacity in towns with many obstacles to travel. Because of this, wheeled armored vehicles have gradually become the main vehicles. However, modern armored vehicles are still unable to make a perfect balance between protection and mobility. They are prone to attend one thing and lose another when designing vehicles, leading to fatal attacks in wars and military mission failure.

For political figures and business tycoons, it is necessary to prevent terrorist attacks when traveling [3].The bullet-proof car was born. In nowadays society, bulletproof cars are necessary means of transportation for some special tasks. During the driving process, the bulletproof vehicle should be able to resist sudden attacks on the vehicle by various non-heavy weapons. On the other hand, the bulletproof vehicle also needs to be able to leave the site of the attack quickly and in time when the attack occurs to protect the safety of passengers [4].Therefore, the research on armored steel is also of great help to improve the proof performance of bulletproof vehicles.