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1、学习好资料欢迎下载第七章应力和应变分析7.1 应力状态概述7.2 二向和三向应力状态的实例7.3 二向应力状态分析解析法教学时数：2 学时教学目标：1.了解一点应力状态的基本概念,进行应力分析的意义。2.介绍平面应力状态的工程实例。3.掌握平面一般应力状态分析解析法。4会应用解析法确定一点应力状态中的主应力、主方向、主剪应力、主剪平面方位及任意给定方位截面上的应力数值。5对空间应力状态做简单介绍。教学重点：1.重点掌握平面一般应力状态分析解析法。2.重点掌握主应力、主方向、主剪应力、主剪平面方位及任意给定方位截面上的应力数值的计算方法。3.理解一点应力状态的分析在构件强度计算中的重要作用。教学
2、难点：难点是对构件危险点处的主应力、主方位客观存在的理解。教学方法：板书 PowerPoint,采用启发式教学和问题式教学法结合，通过提问，引导学生思考，让学生回答问题，激发学生的学习热情。教具：教学步骤：（复习提问）（引入新课）7.1 应力状态概述1 凡提到“应力”，必须指明作用在哪一点，哪个（方向）截面上。因为受力构件内同一截面上不同点的应力一般是不同的，通过同一点不同（方向）截面上应力也是不同的。例如，如图1所示弯曲梁横截面上各点具有不同的正应力与剪应力；如图 2 通过轴向拉伸杆件同一点m的不同（方向）截面上具有不同的应力。一点处的应力状态 是指通过一点不同截面上的应力情况，或指所有方位
3、截面上应力的集合。应力图 1 学习好资料欢迎下载分析就是研究这些不同方位截面上应力随截面方向的变化规律。如图3 是通过轴向拉伸杆件内m点不同（方向）截面上的应力情况（集合）一点处的应力状态可用围绕该点截取的微单元体（微正六面体）上三对互相垂直微面上的应力情况来表示。如图4（a,b）为轴向拉伸杆件内围绕m点截取的两种微元体。特点：根据材料的均匀连续假设，微元体（代表一个材料点）各微面上的应力均匀分布，相互平行的两个侧面上应力大小相等、方向相反；互相垂直的两个侧面上剪应力服从剪切互等关系。在图 2a 中，单元体的三个互相垂直的面上都没有切应力，这种切应力等于零的面称为主平面。主平面上的正应力成为主
4、应力。一般来说，通过受力构件的任意点都可以找到三个互相垂直的主平面，因而每一点都有三个主应力。对简单拉伸，三个主应力中只有一个不等于零，称为单向应力状态。若三个主应力中有两个不等于零，称为二向或平面应力状态。当三个主应力都不等于零时，称为三向或空间应力状态。7.2二向和三向应力状态的实例薄壁圆筒压力容器D为平均直径，为壁厚则薄壁圆筒的横截面上的应力442pDDDPAF（7.1）用相距为l的两个横截面和包含直径的纵向平面，从圆筒中取出一部分（图7.2c），若在筒壁的纵向截面上应力为，则内力为lFN在这一部分圆筒内壁的微分面积dDl2上，压力为dDpl2。它在y方向的投影为sin2dDpl。通过积
5、分求出上述投影的总和为图7.2 图 2 图 3 文档编码:CW3E8F8X8S8 HR8R7Z8S10U3 ZX6U7F7L5J2文档编码:CW3E8F8X8S8 HR8R7Z8S10U3 ZX6U7F7L5J2文档编码:CW3E8F8X8S8 HR8R7Z8S10U3 ZX6U7F7L5J2文档编码:CW3E8F8X8S8 HR8R7Z8S10U3 ZX6U7F7L5J2文档编码:CW3E8F8X8S8 HR8R7Z8S10U3 ZX6U7F7L5J2文档编码:CW3E8F8X8S8 HR8R7Z8S10U3 ZX6U7F7L5J2文档编码:CW3E8F8X8S8 HR8R7Z8S10U3
6、ZX6U7F7L5J2文档编码:CW3E8F8X8S8 HR8R7Z8S10U3 ZX6U7F7L5J2文档编码:CW3E8F8X8S8 HR8R7Z8S10U3 ZX6U7F7L5J2文档编码:CW3E8F8X8S8 HR8R7Z8S10U3 ZX6U7F7L5J2文档编码:CW3E8F8X8S8 HR8R7Z8S10U3 ZX6U7F7L5J2文档编码:CW3E8F8X8S8 HR8R7Z8S10U3 ZX6U7F7L5J2文档编码:CW3E8F8X8S8 HR8R7Z8S10U3 ZX6U7F7L5J2文档编码:CW3E8F8X8S8 HR8R7Z8S10U3 ZX6U7F7L5J2文档
7、编码:CW3E8F8X8S8 HR8R7Z8S10U3 ZX6U7F7L5J2文档编码:CW3E8F8X8S8 HR8R7Z8S10U3 ZX6U7F7L5J2文档编码:CW3E8F8X8S8 HR8R7Z8S10U3 ZX6U7F7L5J2文档编码:CW3E8F8X8S8 HR8R7Z8S10U3 ZX6U7F7L5J2文档编码:CW3E8F8X8S8 HR8R7Z8S10U3 ZX6U7F7L5J2文档编码:CW3E8F8X8S8 HR8R7Z8S10U3 ZX6U7F7L5J2文档编码:CW3E8F8X8S8 HR8R7Z8S10U3 ZX6U7F7L5J2文档编码:CW3E8F8X8S
8、8 HR8R7Z8S10U3 ZX6U7F7L5J2文档编码:CW3E8F8X8S8 HR8R7Z8S10U3 ZX6U7F7L5J2文档编码:CW3E8F8X8S8 HR8R7Z8S10U3 ZX6U7F7L5J2文档编码:CW3E8F8X8S8 HR8R7Z8S10U3 ZX6U7F7L5J2文档编码:CW3E8F8X8S8 HR8R7Z8S10U3 ZX6U7F7L5J2文档编码:CW3E8F8X8S8 HR8R7Z8S10U3 ZX6U7F7L5J2文档编码:CW3E8F8X8S8 HR8R7Z8S10U3 ZX6U7F7L5J2文档编码:CW3E8F8X8S8 HR8R7Z8S10U
9、3 ZX6U7F7L5J2文档编码:CW3E8F8X8S8 HR8R7Z8S10U3 ZX6U7F7L5J2文档编码:CW3E8F8X8S8 HR8R7Z8S10U3 ZX6U7F7L5J2文档编码:CW3E8F8X8S8 HR8R7Z8S10U3 ZX6U7F7L5J2文档编码:CW3E8F8X8S8 HR8R7Z8S10U3 ZX6U7F7L5J2文档编码:CW3E8F8X8S8 HR8R7Z8S10U3 ZX6U7F7L5J2文档编码:CW3E8F8X8S8 HR8R7Z8S10U3 ZX6U7F7L5J2文档编码:CW3E8F8X8S8 HR8R7Z8S10U3 ZX6U7F7L5J2
10、文档编码:CW3E8F8X8S8 HR8R7Z8S10U3 ZX6U7F7L5J2文档编码:CW3E8F8X8S8 HR8R7Z8S10U3 ZX6U7F7L5J2文档编码:CW3E8F8X8S8 HR8R7Z8S10U3 ZX6U7F7L5J2文档编码:CW3E8F8X8S8 HR8R7Z8S10U3 ZX6U7F7L5J2文档编码:CW3E8F8X8S8 HR8R7Z8S10U3 ZX6U7F7L5J2文档编码:CW3E8F8X8S8 HR8R7Z8S10U3 ZX6U7F7L5J2文档编码:CW3E8F8X8S8 HR8R7Z8S10U3 ZX6U7F7L5J2文档编码:CW3E8F8X
11、8S8 HR8R7Z8S10U3 ZX6U7F7L5J2文档编码:CW3E8F8X8S8 HR8R7Z8S10U3 ZX6U7F7L5J2文档编码:CW3E8F8X8S8 HR8R7Z8S10U3 ZX6U7F7L5J2文档编码:CW3E8F8X8S8 HR8R7Z8S10U3 ZX6U7F7L5J2文档编码:CW3E8F8X8S8 HR8R7Z8S10U3 ZX6U7F7L5J2学习好资料欢迎下载0sin2plDdDpl积分结果表明，截出部分在纵向平面上的投影面积lD与p的乘积，就等于内压力的合力。由平衡方程0yF，得02p l Dl2pD（7.2）从公式（7.1）和（7.2）看出，纵向截面
12、上的应力是横截面上应力的两倍。2球形贮气罐（图8-6）壁的内力用包含直径的平面把容器分成两个半球，半球上内压力的合力为42DpF容器截面上的内力为DFN由平衡方程容易得出4pD由球对称知包含直径的任意截面上皆无切应力，且正应力都等于由上式算出的，与相比，如再省略半径方向的应力，三个主应力将是21，033弯曲与扭转组合作用下的圆轴4受横向载荷作用的深梁文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码
13、:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6
14、K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码
15、:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6
16、K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码
17、:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6
18、K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3学习好资
19、料欢迎下载7.3 二向应力状态分析解析法1 空间一般应力状态如图所示，共有9 个应力分量：x面上的xx，xy，xz；y面上的yy，yx，yz；z面上的zz，zx，zy。1）应力分量的下标记法：第一个下标指作用面（以其外法线方向表示），第二个下标指作用方向。由 剪应力互等定理，有：yxxy，zyyz，zxxz。2）平面一般应力状态如图b 所示，即空间应力状态中，z方向的应力分量全部为零（0zyzxzz）；或只存在作用于x-y 平面内的应力分量x，y，xy，yx，其中x，y分别为xx，yy的简写，而xy=yx。3）正负号规定：正应力以拉应力为正，压为负；剪应力以对微元体内任意一点取矩为顺时针者为正
20、，反之为负。2平面一般应力状态斜截面上应力如图 7.5 所示，斜截面平行于z轴且与x面成倾角，由力的平衡条件：0nF和0tF可求得斜截面上应力，：c o ssi n2s i nc o s22xyyx图 7.5 文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z
21、3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J
22、4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z
23、3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J
24、4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z
25、3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J
26、4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3学习好资料欢迎下载2sin2cos)(21)(21xyyxyx（7.3）)s i n(c o sc o ss i n)(22xyyx2cos2sin)
27、(21xyyx(7.4)注意到：1）图 7.5b 中应力均为正值，并规定倾角自x轴开始逆时针转动者为正，反之为负。2）式中xy均为x面上剪应力，且已按剪应力互等定理将yx换成xy。3正应力极值主应力根据（7.3）式，由求极值条件0dd，得02cos22sin)(xyyx即有yxxy22tan0（7.5）0为取极值时的角，应有0，900两个解。从公式（7.5）求出02sin和02cos分别代入(7.3)，(7.4)即得：22m i nm a x4)(21)21xyyxyx（7.6）09000说明：1）当倾角转到0和900面时，对应有0，900，其中有一个为极大值，另一个为极小值；而此时0，900
28、均为零。可见在正应力取极值的截面上剪应力为零。2）定义：正应力取极值的面（或剪应力为零的面）为主平面，主平面的外法线方向称主方向，正应力的极值称主应力，对平面一般应力状态通常有两个非零主应力：max，min，故也称平面应力状态为二向应力状态。4剪应力极值主剪应力根据(7.4)式及取极值条件02sin22cos)(xyyxdd，可得：xyyx22tan1（7.7）1为取极值时的角，应有1，901两个解。将相应值12sin，12cos分别代入(7.3)，(7.4)即得：文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K
29、8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:
30、CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K
31、8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:
32、CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K
33、8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:
34、CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K
35、8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3学习好资料欢迎下载）22minmax4)(21xyyx(7.8)）yx(2190*0*0说明：1）当倾角转到1和901面时，对应有m ax，min，且二者大小相等，方向相反，体现了剪应力互等定理，而此两面上正应力大小均取平均值）minmax(21（如图 8-11b）。2）定义：剪应力取极值的面称主剪平面，该剪应力称主剪应力。注意到：12tan2tan0*090220*0或450*0因而主剪平面与主平面成45夹角。（课堂小节）作业布置：7.4(a)(d)7.7 第七章应力和应变分析7.4
36、 二向应力状态分析图解法7.10 强度理论概述7.11 四种常用强度理论7.12 莫尔强度理论教学时数：2 学时教学目标：1.了解从任意截面上的应力公式引出应力圆的简要过程,即应力圆的方程的导出。2.掌握应力圆的作图方法。3.掌握用应力圆求任意斜截面上的应力、主应力和确定主平面的位置的具体方法。4掌握极点法，明确极点法的优越性。5.了解强度理论的基本概念。6.掌握四种常用的强度理论的内容及其应用条件。7.了解莫尔强度理论及其适用范围。文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文
37、档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U
38、7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文
39、档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U
40、7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文
41、档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U
42、7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文
43、档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3学习好资料欢迎下载教学重点：3.重点掌握应力圆的作图方法。4.掌握用极点法求解任意斜截面上的应力、主应力和确定主平面的位置。5.重点了解强度理论的基本概念。4.重点掌握四种常用强度理论的内容及应用条件。教学难点：难点是学生对材料的机械性能与强度理论之间的内在联系尚不能深刻地理解，特别对从能量原理和唯象处理方法导出的强度理论不一定彻底接受。教学方法：板书 PowerPoint,采用启发式教学和问题式教学法结合，通过提问，引导学生思考，让学生回答问题，激发学生的学习热情。教具：教学步骤：（复习提问）（引入新课）（讲授新课
44、）7.4 平面应力状态分析 图解法1应力圆方程由式（7.3）和(7.4)消去2sin，2cos得到2222)2()2(xyyxyx(a)此为以，为变量的 圆方程，以为横坐标轴，为纵坐标轴，则此圆圆心O坐标为文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B
45、7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4
46、HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B
47、7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4
48、HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B
49、7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4
50、HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3文档编码:CO1H5X9D5J4 HQ4U7J6K8F3 ZR2C8Z3B7F3学习好资料欢迎下载0),(21Yx，半径为21222xyyxR，此圆称 应力圆 或莫尔（Mohr）圆。2应力圆的作法应力圆法也称应力分析的图解法。作图 7