What is compressive residual stress?
In a mathematical sense the term compressive residual stress refers to a negative residual stress condition. For example, shot peening, laser shock peening, and cold expansion are used to impart compressive residual stress, which can significantly enhance structural performance.
What is machining residual stresses?
Residual stresses are the response to the mechanical and structural history of the component during its manufacturing (metal casting, metal forming, machining, heat treatment, etc.) and in service when submitted to external loadings (thermal, mechanical, and chemical).
What is residual stress in a person?
: a stress that exists within a solid body though no external stress-producing forces are acting and that is due to some inequality of previous treatment of adjacent parts poorly annealed glass may be highly unstable because of residual stresses and shatter from a slight shock — compare rupert’s drop.
What is residual stress in forging?
Residual stresses are those stresses that remain in a body when there is no external load applied. Numerous factors can induce residual stresses in the material, including cold forming.
What is an example of compression stress?
Compressional stress is when a rock is pressed together into itself, like when crust movements cause two rocks to squeeze another one between them. Another example is when mountains are formed at a convergent boundary, like the Rocky Mountains. Press your hands together again.
Why is residual stress compressive?
While uncontrolled residual stresses are undesirable, some designs rely on them. A material having compressive residual stress helps to prevent brittle fracture because the initial crack is formed under compressive (negative tensile) stress.
What is machining stress?
This state is the sum of the stress due to the applied load and of the residual stresses (or self stresses) generated during machining. Residual stress is the result of various mechanical and thermal events, which oc- cur in the surface region during machining [3].
Which stress is induced under press metal cutting process?
Initial stress which is generated during the manufacturing steel structure occurs due to a temperature difference on the surface and inner side of steel while it goes through the heating and cooling process during manufacturing.
What causes residual stress?
WHAT CAUSES RESIDUAL STRESS? Residual stresses are generated, upon equilibrium of material, after plastic deformation that is caused by applied mechanical loads, thermal loads, or phase changes. Mechanical and thermal processes applied to a component during service may also alter its residual stress state.
What are sources of residual stresses?
Residual stress also occurs when plastic deformation is non-uniform through the cross-section of an object undergoing a manufacturing process, such as bending, drawing, extruding and rolling. When a material undergoes deformation, one part is elastic and another plastic.
What is the effect of residual stresses in forging?
Residual stresses are inherently introduced to forged products during their deformation. These stresses influence the integrity of load-bearing parts. Their effects depend on their nature (tensile or compressive), location and magnitude.
How do you remove residual stress from steel?
This can be achieved via thermal or mechanical processing. Post-weld heat-treatments are often used to relieve or redistribute the residual stresses in a welded object. From a mechanical perspective, techniques such as shot peening, cold rolling, and stretching can be applied to achieve the desired effect.
What are the effects of residual stress on a structure?
Residual stresses are often invisible to a manufacturer, unless they result in significant distortion, but can negatively affect structural integrity. For example, thick-walled structures in the as-welded condition are more prone to brittle fracture than a structure that has been stress-relieved.
How is residual stress calculated in semi destructive techniques?
The residual stress is then calculated as a function of through thickness position determined by solving an inverse problem using measured deformations. Semi-destructive techniques are comparable to destructive techniques in that they use a strain release principle to determine the residual stress.
When does residual stress occur in a manufacturing process?
Residual stress also occurs when plastic deformation is non-uniform through the cross-section of an object undergoing a manufacturing process, such as bending, drawing, extruding and rolling. When a material undergoes deformation, one part is elastic and another plastic.
How is the contour method used to calculate residual stress?
The contour method determines residual stress by cutting an object into two pieces and measuring surface height maps along the free plane created by the cut. The average contour determines the deformations caused by residual stress redistribution and is used to compute residual stresses through an elastic finite element model of the specimen.