文档介绍：Specification of stress at a point
Tensor notation
Stress on an oblique plane
principal stress and stress invariants
principal shear stresses and maximum shear stress
Morh circle stress diagram
Octahedral stresses
Deviator stresses and its invariants
Differential equations of equilibrium
1 Stress analysis
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1 Stress analysis
Questions:
What is stress?
What is the cause of stress?
How many ponents need we know to specify the unique state of a stressed point in a continuous body?
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Internal forces between molecules
Specification of stress at a point
Stress analysis
internal forces
External forces
Deformation
Mutual position of molecules change
Additional internal forces ☆
External forces
Internal forces
Method of sections
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Forces acts upon body in two ways:
Specification of stress at a point
Stress analysis
Contact and body forces
Act on every particle of the body
Gravitational and ic forces
Act on external surface of the body
Body forces
Contact forces
The theories of elastic and plastic deformation are mainly concerned with:
Contact forces in static equilibrium
Quasi-static
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Stress at a point in a continuous body
The resultant of the continuous distribution of internal forces exerted by part A on part B in the sectioning plane be F.
Specification of stress at a point
Stress analysis
— stress at the point P in the r direction and in the plane of the section considered.
Notes: Stress at a point varies with the plane it acts upon. Therefore, whenever we refer to a stress, we must specify the plane.
? How to specify the stress state of a point
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Stress at a point in a continuous body
Specification of stress at a point
Stress analysis
Q
P
P
σ0
C
C
Q
F0
C1
C1
S
F1
N
θ
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ponents
Resolve the force F into ponents:
Specification of stress at a point
Stress analysis
The normal stress
pletely specify the stress at a poin