1374 Words6 Pages

Chapter -2 Literature review

High stresses are induced when a load is applied to two elastic solids in contact. This can cause serious issues in the optomechanical design if not considered and addressed properly. Contact between two continuous, non-conforming solids is initially a point or line. Under the action of a load the solids deform and a contact area is formed. Hertz contact stress theory allows for the prediction of the resulting contact area, contact pressure, compression of the bodies, and the induced stress in the bodies.

2.1 Analysis of surface and sub-surface cracks due to fatigue D. Finney Charles, R. Gnanamoorthy (2010) investigated rolling contact fatigue (RCF)*…show more content…*

Since all fundamentals of rolling contact fatigue are present in a deep groove ball bearing or a spur gear, these applications are used to exemplify the application mechanics.

As we know the mechanics differs between applications it is realised that the rolling contact consists of some common geometric properties. The nominal contacts can be regarded a two dimensional or line contact where Hertz contact conditions exists.

2.3.1 Hertz pressure Hertzian contact stress refers to the localized stresses that develop as two curved surface come in contact and deform slightly under the imposed load. This amount of deformation is dependent of modulus of elasticity of the material in contact. It gives the contact stress as a function of the normal contact force, radii of curvature of both bodies and modulus of elasticity of both bodies .Hertzian contact stress forms the foundation for the equation for load bearing capabilities and fatigue life in bearings , gears and any other bodies where two surfaces are in contact .

Assumption in Hertzian theory :-

• Strains are small and within the elastic limit

• The surfaces as continuous and non-conforming(implying that the area of contact is much smaller than the characteristic dimensions of the contacting*…show more content…*

Therefore, the material is case hardened, which gives increased surface hardness combined with residual compressive stresses present at the surface. It should be noted that although the hardness and the residual stresses from heat treatment are results of the same process, the material hardness is only dependent on the local material state whereas the residual stress distribution is dependent on the geometry through the equilibrium of expanded and unaffected material. An increasing resistance against surface fatigue with hardness was documented already by Way in 1935. It was also found that the spalls became smaller for a hardened

High stresses are induced when a load is applied to two elastic solids in contact. This can cause serious issues in the optomechanical design if not considered and addressed properly. Contact between two continuous, non-conforming solids is initially a point or line. Under the action of a load the solids deform and a contact area is formed. Hertz contact stress theory allows for the prediction of the resulting contact area, contact pressure, compression of the bodies, and the induced stress in the bodies.

2.1 Analysis of surface and sub-surface cracks due to fatigue D. Finney Charles, R. Gnanamoorthy (2010) investigated rolling contact fatigue (RCF)

Since all fundamentals of rolling contact fatigue are present in a deep groove ball bearing or a spur gear, these applications are used to exemplify the application mechanics.

As we know the mechanics differs between applications it is realised that the rolling contact consists of some common geometric properties. The nominal contacts can be regarded a two dimensional or line contact where Hertz contact conditions exists.

2.3.1 Hertz pressure Hertzian contact stress refers to the localized stresses that develop as two curved surface come in contact and deform slightly under the imposed load. This amount of deformation is dependent of modulus of elasticity of the material in contact. It gives the contact stress as a function of the normal contact force, radii of curvature of both bodies and modulus of elasticity of both bodies .Hertzian contact stress forms the foundation for the equation for load bearing capabilities and fatigue life in bearings , gears and any other bodies where two surfaces are in contact .

Assumption in Hertzian theory :-

• Strains are small and within the elastic limit

• The surfaces as continuous and non-conforming(implying that the area of contact is much smaller than the characteristic dimensions of the contacting

Therefore, the material is case hardened, which gives increased surface hardness combined with residual compressive stresses present at the surface. It should be noted that although the hardness and the residual stresses from heat treatment are results of the same process, the material hardness is only dependent on the local material state whereas the residual stress distribution is dependent on the geometry through the equilibrium of expanded and unaffected material. An increasing resistance against surface fatigue with hardness was documented already by Way in 1935. It was also found that the spalls became smaller for a hardened

Related

## Spherical Bearing Research Paper

1400 Words | 6 PagesThese types of loading can cause material fatigue due to dislocation of the atomic structure of the raceway material, which leads to formation of fatigue. These wear particles circulate along the surface of the raceway, which leads to increasing in wear rate. Fig 2: Types of wear mechanisms Abrasion: Difference in the hardness of the material, which are in contact leads to abrasion. The harder material acts on the softer material abrasively by making roughness (channelling, scratches, etc.) on the surface of the softer material by penetration.

## Pore Pressure Ratio

1549 Words | 7 PagesThen porepressure ratio is equal to pore pressure coefficients B. The knowledge of pore pressure parameters is essential for the determination of effective stress from total stress. Skempton gave the pore pressure parameters which express the response of pore pressure due to changes in the total stress under undrained conditions. These parameters are used to predict pore water pressure in the field under similar condi-tions. Pore pressure coefficient A fluctuates with both the stress value and the rate of strain, due mainly to the variation of Δud with the deviator stress for a given soil.

## Essay On Hardness Testing

1069 Words | 5 PagesIf the materials become harder it will cause much more protection from infiltration. Hardness is straightforwardly correlated with the mechanical properties of the material. Components affecting hardness incorporate microstructure, grain measure, strain solidifying, and so on. subsequently determinations regularly require the consequences of hardness tests as opposed to tensile tests. A few hardness techniques have been created throughout the years in which a little indenter with various size

## Shear Wall Literature Review

1403 Words | 6 PagesThe deflection of the frame is in shear mode, but the wall deflection is in the bending mode. This interaction increases the maximum shear in shear walls and reduces maximum moments. This raises the tendency of shear failure in shear walls and this aspect should be permissible for the

## Shot Peening Research Paper

726 Words | 3 PagesThe changes in the stress state of the material are based on local inhomogeneous elastic-plastic deformations. If the impact-induced stress exceeds the flow stress of the workpiece material, the affected area is being compressed and displaced perpendicularly to the force. Thereby the plastic stretching directly at the surface is the highest and decreases within an increasing distance from the surface. The plastic

## Buckling Theory Of Buckling

856 Words | 4 PagesBuckling: Structures that are subjected to compressive axial loads may fail due to the lateral deflection this phenomenon is known as Buckling. It is demonstrated as by pressing the opposite edges of column towards one another. For small loads the process is elastic as buckling displacement disappears when the load is removed. Local buckling of plates or shells are indicated by bulges, waves or ripples and this are most common in thin structural members. Buckling proceeds in a manner which may be either: Stable- in which displacements increases as load increases but the structure can sustain loads Unstable- in which deformation increases instantaneously and the load carrying capacity of the structure collapses Neutral equilibrium- this is characterized

## Lundberg Palmgren Model

733 Words | 3 PagesAfter that he introduce the table for the choice of roller and needle bearing by the scale and their necessities of loading. He additionally provide variety to those pertaining to the premise of their specification like material properties, applied stress and their life. Zaretsky Model He introduces the important shear stress as a perform of your time. He additionally introduces the construct of high cycle fatigue and low cycle fatigue. In high cycle fatigue the crack promulgate time is incredibly tiny as compared to the overall lifetime of the bearing.

## Essay On Pin Motion Speed

1298 Words | 6 PagesThe trend is very similar to the results obtained in metallurgical studies. • Hardness of the pins and samples are effective on the recorded trends. The speed corresponds to the smallest value of the CAI, decreases with increasing hardness of the samples and decreasing hardness of the pins. • The calculated values of work on the pins during Cerchar tests showed that increasing the pin motion speed, decreases the values of work on the pin and its tip penetration into the sample surface. Hard pins tend to more penetrate but in higher motion speeds the difference of penetration between hard and soft pins

## Friction Welding Research Paper

1995 Words | 8 PagesMechanical and metallurgical investigations were performed. The optimum welding parameters were determined for these working conditions. The microhardness variation across the weld zone was conducted using Vicker?s microhardness test. The response surface methodology was adopted for determining the optimum combination of welding parameters. The regression equation was developed to predict the maximum tensile strength for the optimal parameters.

## Lateral Torsional Buckling Literature Review

1403 Words | 6 PagesAlso the buckling curves are in general. In some situations, other methods and other buckling curves may be used instead. For more detailed explanation refer to Eurocode 3. Stress and Strain Welding stiffener at mid span of a beam had a great effect on the web strain than welding at the end of the beam and welding plates at the top flange affected the web compression strain in the other hand welding plates at the bottom flange affected the web tension strain (zong liang 2014) this outcome will be considered later during the experimental work to find out the possible reason for this result, however the result shows that the compression strain and the tension strain of the web increased relatively but the increasing was very small

### Spherical Bearing Research Paper

1400 Words | 6 Pages### Pore Pressure Ratio

1549 Words | 7 Pages### Essay On Hardness Testing

1069 Words | 5 Pages### Shear Wall Literature Review

1403 Words | 6 Pages### Shot Peening Research Paper

726 Words | 3 Pages### Buckling Theory Of Buckling

856 Words | 4 Pages### Lundberg Palmgren Model

733 Words | 3 Pages### Essay On Pin Motion Speed

1298 Words | 6 Pages### Friction Welding Research Paper

1995 Words | 8 Pages### Lateral Torsional Buckling Literature Review

1403 Words | 6 Pages