What is shear strain What is normal stress Positive strain Shear stress Shear strain

When an object is deformed by force, the degree of deformation at various points in the body is generally not the same. The mechanical quantity used to describe the degree of deformation at a point is the strain at that point.

The binding force at the neck bearing is perpendicular to the rotating shaft, but its direction is unknown, so it is expressed by two components perpendicular to the shaft and perpendicular to each other. The thrust bearing is equal to the neck bearing, and the shelving binding force can be drawn with three components.

One component is along the axis, and the other two components are perpendicular to each other perpendicular to each other. When performing mechanical calculations for complex structures, it is sometimes necessary to fold each component from the connection and draw the force diagram of each component separately, and it is necessary to pay attention to the law of the binding force obeying the action force and the reaction force at the connection on the force diagram.

Common Constraint Types:

1) Set aside the constraint, the binding force along the normal of the contact surface.

2) (column) hinge, where the binding force is perpendicular to the axis of rotation but the direction is undetermined, is usually expressed by two components perpendicular to each other and perpendicular to the axis of rotation.

3) Ball hinge, the binding force is over the center of the ball, but the direction is uncertain, usually expressed by three components that perpendicate to each other.

4) Roller seat, the binding force is perpendicular to the contact surface of the roller seat.

When the element body is a regular hexahedron in Cartesian coordinates, the right-angle change of the two perpendicular edges of the element body after deformation is defined as angular strain or shear strain, which is denoted by . The shear strain of a point in the x-y, y-z, z-x direction, and z-x direction is added to xy, yz, and zx. The shear strain is positive with a reduction at right angles and negative vice versa.

The formula for positive strain is, web link.

where l is the length before deformation and δl is the elongation after deformation.

Shear strain: modulus of elasticity.

e), shear modulus.

g), Poisson's ratio.

v) The formula of the three-way system is: g=e [2(1+v)], there are two main types: linear strain and angular strain. Linear strain, also known as positive strain, is the ratio of the length increment (positive when elongated) to the original length of a small line segment due to deformation in a certain direction; Angular strain, also known as shear strain or shear strain, is the amount of change in the angle between two tiny line segments perpendicular to each other after deformation (expressed in radians, when the angle decreases is the difference of the pix.

The strain is related to the position of the point under consideration and the direction chosen.

1. Normal stress: The stress component perpendicular to the cross-section is called normal stress (or normal stress), which is denoted by . Normal stress indicates the action of tension and compression between two adjacent sections inside the part.

2. Positive strain: At this point, the strain in the length direction generated by the normal stress distributed on the section in a certain direction is called positive strain.

3. Shear stress: The stress component tangent to the cross-section is called shear stress or shear stress, which is depresented. The shear stresses represent the action of mutual dislocation.

4. Shear strain: At this point, the strain in the length direction generated by the shear force distributed on the section in a certain direction is called shear strain. Also known as shear strain.

Stress hazards

1. Cracking. Because of the presence of stress, after being subjected to external action (such as contact with chemical solvents during pad printing or high temperature baking at the back end of the paint), it will induce stress release and crack at the residual stress position. Cracking is mainly concentrated at the gate or where it is overfilled.

2. Warping and deformation.

Because of the existence of residual stress, the product will have a long period of internal stress release at room temperature or a short period of residual stress release process at high temperature, and at the same time, there is a local position strength difference of the product, and the product will have warping or deformation problems at the stress residual position.

3. Product size changes.

Because of the presence of stress, if the environment reaches a certain temperature after the product is placed or during treatment, the product will change due to stress release.

The normal stress is the stress perpendicular to the cross-section, and the corresponding normal stress is the variable perpendicular to the unit length of the cross-section.

The shear stress is the stress parallel to the cross-section, and the corresponding shear strain is the amount of change parallel to the unit length of the cross-section.

These are more involved in the mechanics of materials, and you can refer to the textbook of mechanics of materials.

Here's a note I made, from Wikipedia, shear strain is also called shear strain, and correspondingly, shear stress is also called shear stress.

The stress perpendicular to the cross-section is called normal stress, the dimension is pressure pa, and the amount of length deformation caused by normal stress is called positive strain, which is dimensionless.

Similarly, shear stress is the stress in the tangent direction to the cross-section, dimension PA, shear strain is the amount of angular deformation produced by shear stress, dimensionless.

Elastic modulus. e), shear modulus (g), Poisson's ratio.

v) The formula for the relationship between the three is:

g=e/[2(1+v)]

Poisson's ratio: A material that produces elongated (or shortened) deformation in the direction of the load, while it produces a shortening (or elongation) deformation in the direction perpendicular to the load. The negative value of the ratio of the strain l in the vertical direction to the strain in the direction of the load is called the Poisson's ratio of the material.

Denote the Poisson's ratio by v, then v=- l. In the elastic deformation stage of the material, v is an ivy number.

Shear modulus: refers to the shear stress of the material during the elastic deformation stage.

The ratio to the corresponding shear strain.

Modulus of elasticity: During the elastic deformation stage of a material, its stress and strain are proportional to each other.

That is, in accordance with Hooke's law, its proportional coefficient is called the modulus of elasticity. The unit of modulus of elasticity is dyne per square centimeter. "Modulus of elasticity" is a physical quantity that describes the elasticity of matter, and is a general term that includes "Young's modulus."

Shear modulus", "bulk modulus", etc.

Shear strain is also called shear strain, and correspondingly, shear stress is also called shear stress. Shear stress is the stress in the tangent direction to the cross-section, dimension Pa, shear strain is the amount of angular deformation produced by shear stress.

Linear strain (positive strain): The increment of axial tension or compression is the linear strain, and the positive strain is also called tensile strain; to make it elongated; Negative change is also called compressive strain; Make it shorter.

Shear strain is the proportion of deformation that occurs in an object under the action of shear forces, and it can be used to quantify the degree of deformation that occurs during the shear process. Shear strains and units are common concepts in a variety of physics and engineering fields.

In physics, the single-strand bright bit of shear strain is usually "one" because the definition of shear strain is the ratio of the sliding distance of one layer inside an object relative to the other layer to the distance between them. Since this is a dimensionless proportion, the unit of shear strain is "one".

In engineering, the unit of shear strain is usually "meter" or "decimeter", which represents the proportional relationship between the deformation of the material and the initial size of the material due to shear forces. For example, if a pole is 1 m long and subjected to a shear stress of 1 dm, the shear strain of the pole becomes 1 dm, deforming it by 1%. On the other hand, if the length of the pole is 10 meters and it is subjected to a shear stress of 1 dm, the shear strain becomes 1 dm 10 m and it is deformed.

In conclusion, shear strain is a physical quantity that describes the ratio of shear strength and relative motion of an object, and is an important physical quantity to characterize the strain produced by a material after being subjected to force. In different disciplines and fields of engineering, the units of shear strain vary slightly, but all reflect the strength and degree of shear deformation. <>