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Contact of Nonconforming Surfaces and Temperature Rise on Sliding Surfaces
Published in Kenneth C. Ludema, Oyelayo O. Ajayi, Friction, Wear, Lubrication, 2018
Kenneth C. Ludema, Oyelayo O. Ajayi
Tribological phenomena encountered in many practical systems are due to the stresses imposed on material surfaces in contact and the temperature rise if sliding is involved. Calculation of stresses and deformation between solids in contact is the subject of contact mechanics, a field of study and specialization in itself for many years. Contact mechanics involves mathematical complexity and rigor that is beyond the scope and intent of this book. Indeed, analytical and numerical approaches have been deployed by mechanics-inclined members of the tribological community to the solution of contact problems. There are many commercial numerical packages available for solving contact problems. In this chapter, the basic aspects of contact between surfaces are presented in a form accessible to non-contact mechanics specialists.
Combined Nanoindentation and Finite Element Approach in Natural Hierarchical Structures
Published in Arjun Dey, Anoop Kumar Mukhopadhyay, Nanoindentation of Natural Materials, 2018
Deeksha Porwal, Arjun Dey, A. K. Gupta, Kallol Khan, Anand Kumar Sharma, Anoop Kumar Mukhopadhyay
On the other hand, in the case of displacement BC nonlinearity, the displacement boundary condition is dependent on the deformation of the structure. The most important application of displacement BC nonlinearity happens in the contact problem. A typical example of nonlinear problem with contact boundary conditions is schematically shown in Figure 8.5. The indentation is an excellent example of contact problem. The study of two contact bodies and the applications of the theory have become a new discipline, “Contact Mechanics” [8]. The theory of contact mechanics is concerned with the stresses and the corresponding deformations that arise when the surfaces of two solid bodies are brought into contact.
Importance of Simulation in the Design of Experimental Tests
Published in Nigel Powers, Dan M. Frangopol, Riadh Al-Mahaidi, Colin Caprani, Maintenance, Safety, Risk, Management and Life-Cycle Performance of Bridges, 2018
Contact mechanics is the study of the deformation caused by solid bodies that touch each other at one or more points (Popov, 2010). In this study, contact between the HP section and the connection plates is defined as surface-to-surface contact type. This contact type is established when a surface of one body comes in contact with the surface of another body. This contact type is commonly used for arbitrary bodies that have large contact areas (Thomas et al. 2006, Al-Mughairi et al. 2010). In this study, frictionless contact is chosen between the HP section and connection plates as gaps form in the model between contacting bodies. For the remainder of the model, bonded contact is chosen (for the contact with the side plates of the steel base fixture as shown in Fig.4).
Effect of Elastic Contact Force on Tribological Characteristics of Current-carrying Roll Rings in Rotating Conductive Joints
Published in Tribology Transactions, 2023
Tianhua Chen, Chenfei Song, Zili Liu, Li Wang, Chao Sun, Xianjuan Pang, Yongzhen Zhang
The normal force and friction coefficient at a single contact point during the steady-state stage of rolling were shown in Fig. 9, which further explained the damage caused to the contact surfaces. Based on contact mechanics, (20) the surface yield strongly depended on the friction coefficient, and a higher friction coefficient (above 0.35) could give rise to a larger shear stress toward the surface, thereby causing the surface to yield. In this study, the friction coefficient decreased with an increase in the elastic force. Therefore, the fluctuation was more severe at a lower elastic force because fatigue occurred directly on the wear surface. Cracks were observed below the contact surface when the friction coefficient was <0.35. When the friction coefficient was larger, the surface fatigue was more evident, but the cracks below the surface tended to disappear.
Studies of frictional sliding contact by molecular dynamics assisted continuum mechanics
Published in Mechanics of Advanced Materials and Structures, 2022
Mohsen Motezaker, Shaoping Xiao, Amir R. Khoei, Jabbar Ali Zakeri
However, a full atomistic simulation of a contact system could be time-consuming and impractical. One of the solutions is multiscale modeling [21, 22], which has been applied to study the mechanics of materials in the materials science community. A general hierarchical multiscale method [23] passes the effective material properties or the material-behavior predictive models from a small scale to a large scale. Thus, a similar approach can be employed to study the physical phenomena of lubrication at the nanoscale and simulate the contact mechanisms at the macroscale [24]. Such a multiscale model that bridges MD to continuum mechanics for evaluating contact mechanics can consider the friction phenomena from its origin along with the advantages of classical continuum theory. Ghaffari et al. [12] used a multiscale modeling approach to calculate the rolling contact fatigue (RCF) lifetime with a friction coefficient obtained from MD. However, they considered octane hydrocarbon at room temperature only to model an elastohydrodynamic lubricated rolling system. It is vital to study the effects of lubricant chemical formulation and temperature on the friction coefficient and the sliding contact mechanisms.
Thermal wave propagation in a functionally graded annular fin with fixed base
Published in Waves in Random and Complex Media, 2021
A. Yıldırım, M. Eker, D. Yarımpabuç, K. Celebi
Functionally graded material (FGM) was first proposed by Japanese scientists for a thermal barrier to obtaining high resistance material for high temperature and temperature difference in 1984. FGM is a composite material consisting of ceramic at the high-temperature region and metal at low-temperature region [38], and used as an alternative the laminated composites due to its outstanding thermal and mechanical features [39]. To avoid possible catastrophic failure of fins made of homogeneous materials and meet needs in modern industries such as high performance and relatively lightweight utilizing functionally graded materials are one of the right choices. The continuously and smoothly variation of thermomechanical properties from one surface to the other in FGMs offers betterment that is not obtainable use of homogeneous materials. These can be exemplified by the thermal conductivity, which has to be defined by the spatial dependence, as it accurately predicts the fin's thermal performance [40]. Too many studies with mechanics of FG material model are available such as elasticity [41], thermoelasticity [42–44] and contact mechanics [45–49]. In addition to these, there are many studies available in literature specifically for FGM fin.