Thermomechanical Contact Research Articles

Impact of frictional heat and electric charge on the thermomechanical contact properties of piezoelectric quasicrystals: A DC-FFT algorithm

Piezoelectric quasicrystals (PEQCs) are quasicrystals with piezoelectricity. It combines the excellent properties of piezoelectric materials and quasicrystal materials, and is expected to be used as actuators in fields such as aerospace, automotive, and intelligent manufacturing. This article investigates the physical and mechanical properties of one-dimensional hexagonal piezoelectric quasicrystals (1D HPEQCs) coating under normal force and frictional heat and current density by using the discrete convolution-fast Fourier transform (DC-FFT) algorithm-based hybrid element method (HEM). The general solution of the model in the two-dimensional Fourier domain is obtained by combining the two-dimensional Fourier transform with strict operator theory and the Almansi’s theorem. The DC-FFT algorithm-based HEM is used to efficiently and accurately cope with the issue of transforming the fundamental solution in the Fourier domain into the spatial domain. Therefore, the numerical solutions and distribution of stress and displacement in the phonon and phason fields are obtained. The results indicate that current density has a significant impact on the phason field, and an increase in current density enhances the mechanical behavior of the phason displacement. The research results can provide theoretical guidance for 1D HPEQCs as intelligent coating materials.

Partial Slipping of Flat Punch in Thermomechanical Contact with Elastic Half-Space

Partial Slipping of Flat Punch in Thermomechanical Contact with Elastic Half-Space

Influence of Corrosion on Thermo-Mechanical Contact Fatigue in Rolling Conditions with Low Amplitude Sliding

The paper presents some aspects concerning mechanical contact fatigue and corrosion wear and the links of these two kinds of wear in the common deterioration of the contact layer. The surface state, for both presented areas, is analyzed using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) in order to confirm the double action of corrosion and wear during the experimental test. 2 and 3D insights were taken from the worn area, corrosion compounds were identified and analyzed. Linear and cyclic potentiometry were performed on the base materials after the OCP was established in salt solution. When the level of the thermal and the mechanical stress are located at the same depth under the contact surface the resulting stress is greater and has the opportunity to develop the first crack to the surface. The metallic material surface presents a double type of corrosion: one based on oxidation and the other one based on oxidation plus wear (tribo-corrosion), the difference is being given by the material quantity and type involved.

Numerical modeling of systems based on SMA wires and pulleys: A finite element formulation within the Arbitrary Lagrangian–Eulerian framework

Thanks to their properties of superelasticity and shape memory effects, SMA wires are often considered for the design of damping devices or actuators coupled to pulleys. In order to dimension such devices for commercialization, it is necessary to develop reliable, robust and fast numerical tools. To this end, simplifying the management of the wire/pulley contact using an Arbitrary Lagrangian–Eulerian (ALE) formulation is an original and effective solution. In this work, the wires are modeled by three-dimensional truss thermo-mechanical finite elements associated with a superelastic law. For each node, the curvilinear abscissa is used as an additional degree of freedom in order to deal with material flow from one element to another. After presenting the ALE formalism and the necessary precautions (advection of variables), as well as the material behavior and thermo-mechanical contact laws at the pulleys, elementary validation tests are studied. Finally, two devices taken from the literature are modeled using the ALE formalism. The results obtained demonstrate the relevance and effectiveness of the approach adopted, as well as the importance of not neglecting friction at the pulleys and thermal effects on the material mechanical response.

Peridynamic modeling of rail wear during sliding contact considering thermal effects

Numerical simulations of rail wear during sliding contact pose significant challenges owing to the complex coupling between thermomechanical contact loads, material properties, and profile changes. This study proposes a modeling approach for rail wear during sliding contact, using nonlocal peridynamic (PD) thermomechanics and a bond damage criterion based on ratchet failure. To facilitate test verification, a two-dimensional PD model for twin-disc testing with elastoplastic materials was developed, and numerical simulations and corresponding twin-disc testing were performed during wheel idling under different loads, idling speeds, and idling times. The PD model accurately predicted rail wear under all operating conditions, exhibiting excellent agreement with the test results, and thus validating the proposed method and supporting the ratchet failure mechanism. Subsequently, thermomechanical modeling of sliding contacts with different creepages was performed. The PD model predicted continuous wear along the contact surface, with an increase in wear depth corresponding to higher creepage values. As the contact temperature increased with creepage, thermal stress and thermal softening caused slight and sharp increases in rail plastic strain, respectively. Therefore, thermal softening is the main factor responsible for the significant increase in wear rate with temperature. Finally, wear results of the PD model and classical Archard’s wear model were compared. The PD models can capture variations in wear rates that are difficult to address using the Archard model.

An approach to grid-to-rod fretting wear modeling using dynamic mortar contact

This article presents the development of a grid-to-rod fretting (GTRF) modeling methodology that utilizes dynamic mortar contact. We leverage a recently developed computational framework for modeling thermomechanical contact in dynamic simulations from the nuclear fuel performance code Bison. Usage of mortar contact ensures a smooth distribution of normal and frictional contact forces, displacements, and velocities on the contact interface, thus facilitating an accurate computation of wear. The integration within an advanced nuclear fuel performance code enables analysis of complex interactions between the fuel, cladding, and spacer grid. Such interactions include swelling, creep, fuel fragmentation, burnup, plenum pressure, and fission gas release. Our methodology is demonstrated via the modeling of two spacer grid geometries and the influence of fuel-cladding mechanical contact on the generation of fretting wear.

A study of the radiation thermal boundary conditions influence in three-dimensional thermomechanical contact problems

Any body, by the simple fact of having a certain temperature on its surface, emits heat in the form of electromagnetic radiation. The heat flux emitted is proportional to the fourth power of the temperature of the solid, increasing the inherent non-linearity of the thermomechanical problems. This energy transfer, for systems at high temperatures, has greater relevance than the possible exchange of heat between bodies in contact by conduction or convection processes with a surrounding fluid in the interstitial areas. For this reason, this work presents a robust formulation to study three-dimensional thermomechanical contact problems where radiation boundary and interstitial conditions are simulated. The Boundary Element Method is used to compute the thermomechanical influence coefficients, and a double iterative procedure is used to ensure the achievement of the thermomechanical contact conditions. The final non-linear thermomechanical system of equations is solved using a Newton-Raphson procedure. The proposed formulation is validated with a comparison with some benchmark problems found in the literature and afterward applied to solve different three-dimensional thermomechanical contact problems where the thermomechanical variables are greatly affected by radiation boundary and interstitial conditions.

A numerical assessment of partitioned implicit methods for thermomechanical problems

Implicit partitioned methods for solving thermomechanical problems possess various advantages over monolithic schemes, such as flexibility and simplicity of implementation, at the cost of performance and robustness. This contribution’s primary purpose is to explore suitable partitioned implicit techniques for solving the thermomechanical problem with different sources of coupling. The spatial and time-discrete problem is reformulated as an equivalent root-finding problem using single-field solvers. This work considers the fixed-point method, Aitken relaxation, multisecant quasi-Newton methods, Newton–Krylov method, and polynomial vector extrapolation techniques in cycling mode, which are selected from the relevant literature. These techniques are employed to solve three different problems, including thermoelastic and thermoplastic constitutive behaviors, as well as thermomechanical contact. The methods are compared based on the CPU runtime and the number of residual evaluations, considering as well the memory requirements and the implementation effort. Overall, Broyden’s method can be regarded as the best performing and most advantageous method, with the Aitken relaxation also providing a very efficient and simple alternative. This work brings new insights into the application of partitioned implicit methods to thermomechanical problems and can motivate the selection of these techniques, which are not currently widespread in the community.

Equipment for thermo-mechanical contact fatigue in rolling conditions determination

The paper refers to the influence of corrosion on the installation and development of thermos - mechanical contact fatigue on metallic elements. The analysis takes into account the influence of the thermal Jacq effect on the position of the origin of a crack following the thermos - mechanical contact fatigue. Here are presents some aspects concerning mechanical contact fatigue and corrosion wear and the links of these two kinds of wear in the common deterioration of the contact layer. Schematic draw of the test stand is presented with the main component elements and thermal anomaly effect Jacq in heat conduction was analyzed. To validate the theoretical aspects presented, a test rig is introduced and an experimental program of testing is developed.

Thermomechanical Contact of Elastic Bodies with Nonlinear Winkler Surface Layers

Thermomechanical Contact of Elastic Bodies with Nonlinear Winkler Surface Layers

A mortar thermomechanical contact computational framework for nuclear fuel performance simulation

Nuclear fuel performance simulations involve the modeling of complex physical phenomena, ranging from fission gas release to fuel swelling and other temperature-induced effects. For light-water reactors (LWRs), swelling of the fuel and the pressure it imposes on the clad when they come into contact causes permanent clad deformation. Accurately characterizing the fuel-cladding interaction, which involves multiple physics, is essential to accurately simulate the fuel/cladding system. Thermomechanical modeling of this problem using a variationally consistent enforcement (e.g., a mortar approach) has been shown to improve the quality of results and facilitate convergence. Here, we present a general multiphysics computational framework for solving nuclear fuel problems using a mortar approach in BISON, a nuclear fuel performance code. Analyses show that using the mortar approach, which enables variationally consistent constraint enforcement, improves the quality of results as compared to the more commonly used node-on-face enforcement for representative LWR nuclear fuel simulations.

Thermomechanical analysis of the effect of contact forces in heat conduction of composite materials through multiscale contact finite element modeling

The present study proposes a thermomechanical surface contact finite element formulation for studying interfacial heat conductance in correlation to micromechanical contact forces. The proposed methodology is applied for modeling heat surface conductivity of Carbon Nanotubes (CNT). The atomic lattice of CNTs is initially modeled using the molecular structural mechanics approach and reduced to an equivalent 2D continuum element. The equivalent 2D continuum element is used as a robust and efficient surrogate model for the construction of full length CNTs in contact. Coupled structural and heat pde’s have been used to describe the corresponding thermomechanical problem which are discretized using 2D quadrilateral finite elements, along with surface contact elements based on the Node to Node and Node to Segment formulations. The problem has been treated as a nonlinear steady state problem and solved in the frame of a Newton-Raphson incremental-iterative scheme. Extensive sensitivity analysis was performed with respect to several influencing parameters, such as initial contact angle, boundary conditions and CNT overlapping. Based on this analysis, the effect of overlapping and approaching angle on the total heat exchange was quantified. It has been demonstrated that in most cases, increasing the total contact force can produce an almost linear increase in heat exchange. However, in cases of small approaching angles between CNTs an extensive contact force could heavily deform the contacting geometries producing a non-linear heat exchange mechanism.

3D thermoelastic solids under non‐linear interface thermal and orthotropic frictional contact conditions

AbstractThis article presents a robust and efficient methodology to study three‐dimensional thermoelastic contact problems under orthotropic friction conditions, including the effects of non‐linear thermal contact conductance and convective boundary conditions at the interstitial contact zone. The proposed methodology considers the boundary element method to compute the thermomechanical influence coefficients and an augmented Lagrangian formulation to ensure the fulfillment of all these thermomechanical contact conditions. The resulting non‐linear equation set have been solved by an efficient proposed iterative Uzawa scheme. The proposed formulation has been validated by comparison with some available results in the literature and later on, it is considered to study how the thermoelastic contact variables are affected by both: the non‐linear interface thermal and the orthotropic friction conditions in different engineering problems such as a brake disc‐pad contact system.

Analysis of the contact mechanics in machining using a novel high-speed tribometer

A new high-speed pin-on-bar type tribometer has been developed to study the variation of the friction coefficient with respect to the local thermomechanical contact conditions between the tool and the workpiece when drilling C45 steel. The forces and temperatures are measured over a range of pin indent depths and sliding velocities in open and closed loop tribo-systems. The tribometer’s ability to recreate the thermomechanical contact conditions in drilling is demonstrated and the induced surface modification in the workpiece by the tribology testing is studied.

On the transient thermomechanical contact simulation for two sliding bodies with rough surfaces and dry friction

A transient thermomechanical contact model for two sliding bodies with rough surfaces is presented. The underlying equations are solved for mechanical, thermal and thermoelastic submodels from which dimensionless influence functions for a loaded rectangular element on a halfspace are derived. They can be used to calculate displacements, stresses as well as temperature distributions for arbitrarily shaped and time dependent heat sources or stress distributions on the surface. All formulas are verified by comparison to solutions from the literature. The submodels are afterwards combined into one thermomechanical simulation model by coupling the heat flux to the frictional power while avoiding the use of a prescribed friction coefficient. The solution process is described in detail. Calculations for two nominally flat but periodic rough surfaces with 256 × 128 elements are performed for a range of sliding velocities and indentations. Simulation results are discussed in particular with regard to the obtained transient friction coefficient.

Strong-form meshfree collocation method for multibody thermomechanical contact

Strong-form meshfree collocation method for multibody thermomechanical contact

A chemo-mechano-thermodynamical contact theory for adhesion, friction, and (de)bonding reactions

This work presents a self-contained continuum formulation for coupled chemical, mechanical, and thermal contact interactions. The formulation is very general and, hence, admits arbitrary geometry, deformation, and material behavior. All model equations are derived rigorously from the balance laws of mass, momentum, energy, and entropy in the framework of irreversible thermodynamics, thus exposing all the coupling present in the field equations and constitutive relations. In the process, the conjugated kinematic and kinetic variables for mechanical, thermal, and chemical contact are identified, and the analogies between mechanical, thermal, and chemical contact are highlighted. Particular focus is placed on the thermodynamics of chemical bonding distinguishing between exothermic and endothermic contact reactions. Distinction is also made between long-range, non-touching surface interactions and short-range, touching contact. For all constitutive relations, examples are proposed and discussed comprehensively with particular focus on their coupling. Finally, three analytical test cases are presented that illustrate the thermo-chemo-mechanical contact coupling and are useful for verifying computational models. Although the main novelty is the extension of existing contact formulations to chemical contact, the presented formulation also sheds new light on thermo-mechanical contact, because it is consistently derived from basic principles using only a few assumptions.

Effects of diffused hydrogen atoms on thermomechanical properties and contact behavior of a diamond-like carbon film

Hydrogen atoms are doped to diamond-like carbon (DLC) to improve its thermomechanical properties and tribological performance as a surface protective coating. In this study, molecular dynamics (MD) simulations are performed to investigate the impacts of diffused H atoms on the mechanical stiffness, surface energy, specific heat, and thermomechanical contact behavior of DLC. The hydrogenated DLC (a-C:H) is prepared by adding H atoms to a fixed amount of C atoms (method 1) and by replacing C atoms in DLC with H atoms (method 2). The atomic percentage of hydrogen (at. % H) in DLC is varied from 0 to 8.6%. From the systematic MD simulation results, it is observed that the DLC's mechanical stiffness increases with at. % H due to the increasing density with a higher sp3%, but it shows a decreasing trend for method 2 due to the decreasing density. During the sliding contact with a hemispherical diamond tip, the a-C:H samples show a lower coefficient of friction (COF) than the hydrogen-free DLC (ta-C) sample for method 1 but a higher COF for method 2, which can be attributed to the changes in density and surface energy with respect to hydrogen contents in DLC.

Modelling and simulation of a dynamic contact problem in thermo-piezoelectricity

In this work, we numerically study a dynamic frictional contact problem between a thermo-piezoelectric body and a conductive foundation. The linear thermo-electro-elastic constitutive law is employed to model the thermo-piezoelectric material. The contact is modelled by the Signorini condition and the friction by the Coulomb law. A frictional heat generation and heat transfer across the contact surface are assumed. The heat exchange coefficient is assumed to depend on contact pressure. Hybrid formulation is introduced, it is a coupled system for the displacement field, the electric potential, the temperature and two Lagrange multipliers. The discrete scheme of the coupled system is introduced based on a finite element method to approximate the spatial variable and an Euler scheme to discretize the time derivate. The thermo-mechanical contact is treated by using an augmented Lagrangian approach. A solution algorithm is discussed and implemented. Numerical simulation results are reported, illustrating the mechanical behavior related to the contact condition.

Variational multiscale method for fully coupled thermomechanical interface contact and debonding problems

In this study, a computational framework is proposed for thermomechanical contact and debonding problems with proper thermal resistance at the interface. Using the Variational Multiscale (VMS) framework, we present a fully coupled thermomechanical formulation with an explicit expression of the pressure at the contact interface. The formulation considers the quasi-static balance of the momentum and the transient heat transfer problem in a fully coupled fashion. At the interface, two different contact constitutive models are utilized for tension and compression. For tensile problems, in the mechanical phase, a tensile debonding model is employed, whereas in the thermal phase, the displacement-dependent model is employed. For compressive problems, in the mechanical phase, a Coulomb frictional model is employed while in the thermal phase, a pressure-dependent model is embedded. Because of the naturally derived interface stability terms that possess area- and stress-weighting, the proposed VMS formulation accommodates contact/debonding and contact/frictional sliding at the interface due to both thermal and mechanical loading without losing numerical stability. The proposed method is applied to a class of numerical test problems with discontinuity at the interfaces, and good agreement with analytical and numerical data is achieved.