文档介绍：CHAPTER 8
Mechanics of Materials
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材料力学
第八章强度理论
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CHAPTER 8 STHENGTH THEORIES
§8–1 Concepts of strength theories
§8–2 Four strength theories and their equivalent stresses
§8–3 Mohr’s strength theory and its equivalent stress
§8-4 Applications of strength theories
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第八章强度理论
§8–1 强度理论的概念
§8–2 四个强度理论及其相当应力
§8–3 莫尔强度理论及其相当应力
§8-4 强度理论的应用
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1、Opening words:
§8–1 CONCEPTS OF STRENGTH THEORIES
1)、Investigation of the tensile, compressive and torsional tests of cast iron
and low-carbon steel
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Low-carbon steel
Cast iron
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P
Tension of cast iron
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Compression of cast iron
2)、How will the member rupture bined deformations?
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STRENGTH THEORIES
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一、引子:
§8–1 强度理论的概念
强度理论
1、铸铁与低碳钢的拉、压、扭试验现象是怎样产生的?
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低碳钢
铸铁
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铸铁拉伸
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铸铁压缩
2、组合变形杆将怎样破坏?
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P
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2、Theories of strength:Some assumptions about the cause of the strength failure of materials .
3、Types of failure of materials:⑴ yield; ⑵ rupture
1)、Galileo planted the seed of the first strength theory;
2)、Mariotto’s statement about the rupture of material due to excessive deformation is the flush of the second strength theory;
3)、 proposed the theory of the maximum shearing stress;
4)、Maxwell brought forward the theory of the maximum distortional energy theory early, which was known after his letters were published.
STRENGTH THEORIES
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二、强度理论:是关于“构件发生强度失效(failure by lost
strength)起因”的假说。
1、伽利略播下了第一强度理论的种子;
三、材料的破坏形式:⑴屈服; ⑵断裂。
2、马里奥特关于变形过大引起破坏的论述,是第二强度理论的萌芽;
3、杜奎特()提出了最大剪应力理论;
4、麦克斯威尔最早提出了最大畸变能理论(maximum distortion energy theory);这是后来人们在他的书信出版后才知道的。
强度理论
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§8–2 FOUR STRENGTH THEORIES AND THEIR EQUIVALENT STRESSES
1、Theory of the maximum tensile stress(the first strength):
This theory considers the main cause of rupture to be the maximum tensile stress. The member will rupture as the maximum tensile stress reaches the strength limit in axial tension.
STRENGTH THEORIES
1)、Criterion of rupture:
2)、strength condition:
3)、Application ra