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Even though the influence of impact energy on the low velocity impact of laminated plate is well reported, the influence of relative mass of the impactor has not been addressed extensively. This work investigates the effect of impactor mass relative to that of target and other associated factors like impactor velocity and the target plate size on the impact response of a GLARE plate. A 3 D finite element analysis incorporating Newmark-β method and Hertzian contact is used considering appropriate contact stiffness to evaluate the contact force. Results show that the impactor mass significantly influences the contact force and interfacial delamination. [ABSTRACT FROM AUTHOR]

• A novel dual-rotor-bearing-casing coupling model for aero-engine is established based on the finite element method. • The casing is discretized by the shell element and the modified Craig–Bampton method is utilized for model reduction. • The coupled bending-torsional effect has been studied in detail. • A nonlinear bearing model and the rub-impact effect was introduced in this study. In this study, a novel modeling method for a dual-rotor-bearing-casing system is proposed based on the finite element method (FEM) and the model reduction method. The dual-rotor system is modeled using Timoshenko beam and rigid disc elements, while the casing is modeled using shell elements. To reduce the number of degrees of freedom (DOFs), the modified Craig–Bampton method is used to downscale the finite element model of the casing. In addition, the Hertzian contact force and the DOFs of the bearing outer race and pedestal are considered in the bearing model. Through a specific assembly method, a dynamic model of the dual-rotor-bearing-casing is established at the expense of slight increase in the number of DOFs. Based on this dynamic model with fewer DOFs, the effects of two disc imbalances and the rub-impact fault between the low-pressure (LP) turbine and casing are then introduced as an application of the proposed model. The calculation results indicate that the critical speeds of each order of the whole aero-engine model are significantly lower than those of the casing-free model. In the amplitude-frequency diagram, the peak of the critical speed of the whole aero-engine model is found to appear earlier, and the extent of rightward bending is larger. The study also includes parametric analysis to examine the effects of parameters such as the coefficient of friction, the casing-disc contact stiffness, and the casing-foundation connection stiffness. After introducing the nonlinear bearing model, a large number of fractional frequency components are found in the frequency-domain diagram, the dynamic characteristics of the model become more complicated. The coupled bending-torsional effect has also been studied in detail, the calculation results show that it is reasonable to ignore the torsional deformation. [ABSTRACT FROM AUTHOR]

Purpose: Track irregularities contribute a large impact on the vibrations of a railcar. Therefore, this research is about assessing the impact of track irregularities on the rail vehicle vibration in the case of Addis Ababa Light Rail Transit Service. To assure the comfort of passengers in the railcar, it is important to monitor and identify rail irregularities that lead to rail-car uncomfortable vibrations. The objective of this research is to establish a method that uses rail irregularity measurement data and railcar design parameters to determine the railcar vibrations levels and frequency spectrum. Method: To achieve the objective, the analytical vibration equations of the half-railcar model with twelve degrees of freedom were derived and solved using MATLAB. The impact of periodic track irregularities on a bogie's primary rubber-made suspension materials was also analyzed in MATLAB. On the other hand, a 3D bogie lumped model with the railcar mass via secondary suspension and with Hertzian contact effects neglected in finite element model was analyzed to validate the analytical modal equations. The natural frequencies provided by 3D Finite Element Method (FEM) with full dimensions are compared with those obtained using lumped parameter model analytically. Results: The frequency of the car-body that corresponds to bounce motion provided by lumped parameter model was 14.89Hz, while the frequency obtained from modal analysis by FEM was 13.829Hz. Then, conformity of the frequencies in both models provided confidence in the correctness of the analytical model. The displacement of the railcar found was low and cannot cause fatigue to the vehicle components. Conclusion: As the significance of this research, rail irregularities that lead to a car-body vibration frequency spectrum that produces an uncomfortable ride can be carefully investigated to eliminate their effect, with reference to ISO 2631, which defines the methods for measuring human vibration levels and their effects on comfort. Their effect must be eliminated in the railway lines by either correcting the track or using appropriate railcar suspension parameters. [ABSTRACT FROM AUTHOR]

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As a critical element of time-varying mesh stiffness (TVMS), contact stiffness of a gear drive has been defined based on simplified Hertzian contact stiffness or semi-empirical nonlinear Hertzian contact stiffness in previous works. This study proposes a general contact stiffness model for elastic bodies through piecewise linear interpolation of contact pressure. The TVMS of a spur gear drive is determined through potential energy method and proposed contact stiffness model verified by Hertzian contact theory and finite-element method. Then, the influence of applied load on contact stiffness is studied, and the differences among proposed contact stiffness, simplified Hertzian contact stiffness, and nonlinear Hertzian contact stiffness are analyzed. Results show that contact stiffness increases with the applied load, and the TVMS based on the proposed contact stiffness model is the smallest among the three contact stiffness models. Effects of tooth width and input torque on the TVMS are further discussed. The TVMS becomes bigger with increased tooth width and input torque, but the increase rate decreases as tooth width or input torque increases. These findings indicate that reasonable matching of design parameters is beneficial for increasing load capacity and optimizing the dynamic performance of gear systems. [ABSTRACT FROM AUTHOR]

Finite element analyses based on higher-order shear deformation theory (HSDT) are presented to study low-velocity impact behavior of pre-twisted sandwich conical shell panels having functionally graded carbon nanotubes-reinforced composite (FG-CNTRC) facings. The temperature-dependent material properties of the FG-CNTRC facings are determined utilizing micromechanical models. The dynamic equilibrium equation of the impacted sandwich panel is formulated using Lagrange's equation, wherein modified Hertzian contact law is used to evaluate contact force. The solutions of the resulting equations are obtained using Newmark's time integration method. Finally, the effects of various parameters on the impact response of FG-CNTRC sandwich conical shell panel are analyzed. [ABSTRACT FROM AUTHOR]

The objective of this paper is to elucidate the response to contact stresses of Polymer Infiltrated Ceramic Network (PICN) using the microscopic viscoplastic finite elements, validated by clinically relevant in vitro tests. A feldspathic ceramic material, namely Vita Mark II, is an interconnected structure infiltrated with the polymer (PMMA). Axisymmetric finite element microstructure models are reconstructed from two-dimensional images of a PICN microstructure. Viscoplastic finite element analysis (FEA) with various degrees of microscopic damages occurring over contact is performed. The force-displacement responses obtained from FEA are validated with Hertzian contact tests. Finite element results for force-displacement, stresses and strains in each phase are discussed. We hypothesize that the resistance to fracture of PICN can be further improved by microstructural tailoring. The experimental evidence suggests that a composite material is both more resistant to displacement under load and more resistant to crack initiation and propagation, as hypothesized. Further parametric study on the effects of various volume fractions of two phases in PICN is done to provide some insight on increased contact damage resistance of PICN as well as potential optimization of microstructures. [ABSTRACT FROM AUTHOR]

This paper aims to elucidate the exceptional high strength of Prince Rupert's Drops (PRDs). PRDs are idealized as thermally strengthened Glass Spheres (SGSs), and their compressive failure mechanisms are investigated experimentally and numerically. The distributions of residual stress within SGS specimens are quantitatively characterized using an integrated photo-elastic method. Uniaxial compression tests conducted on these specimens reveal that the compressive residual stress present on the sphere's surface significantly enhances its strength. High-speed video images demonstrate that SGSs fail at the equatorial region, in contrast to annealed glass spheres (AGS) which typically fracture near the Hertzian contact zone. Numerical simulations suggest that the residual stress mitigates the maximum principal stress on the surface of SGSs, thereby impeding the development of flaws on the surface of the specimens. Ultimately, failure of SGS specimens under pressure occurs due to the "squeezing" effect, in contrast to AGSs which commonly fail due to contact indentation. (a) Residual circumferential stress of three strengthened glass spheres (SGS) and compressive failure forces ("strength") of annealed glass sphere (AGS) and SGS. (b) A mechanism based on the initiation and expansion of surface cracks was proposed to explain the extremely high compressive strengths of SGS. [Display omitted] • Strengthened glass spheres with different residual stress were fabricated. • The high destructive forces were measured in uniaxial compression experiments. • Finite element method was utilized to predict the stress of compressed glass spheres. • A mechanism was found for the extreme force based on crack opening and expansion. [ABSTRACT FROM AUTHOR]

Immersed boundary finite element method (IBFEM) seeks to use accurate geometry of structures defined using equations of its boundaries and immersed in a background mesh for finite element analysis. The background mesh is non-conforming and is often a uniform Cartesian mesh which is used to approximate the trial solution. A variety of approaches to apply boundary conditions and evaluate stiffness have been proposed in the literature. A method for modeling contact between solids for IBFEM is presented where the equations of the contacting boundaries are used to construct trial solutions that satisfy contact conditions at the interface between solids. The method is applied here for small deformation elastic problems to model tied contact with or without initial gap or interference between the undeformed geometry of the objects. This approach is particularly suited for IBFEM because the background mesh does not conform to the geometry of the analysis domain and the nodes of the mesh may not be on the boundaries or the contact interfaces. Several contact problems that have analytical solutions are used here to validate the step boundary method. [ABSTRACT FROM AUTHOR]

• Developed a theoretical model for the conformal analysis of circular islands and substrates. • Predicts conformal behavior on surfaces of any curvature and modulus. • Proposed a generic strategy for conformal electronics in various applications. This paper introduces a set of design criteria that aim to integrate flexible electronics onto three-dimensional surfaces in a mechanically adaptive manner. Previous studies have been limited to conformal integration on specific shapes (Such as spherical surfaces and corrugated surfaces) of rigid surfaces or soft substrates, there is a lack of a universal design strategy that takes into account the complexity of substrate shapes and varying hardness. To address this gap, the paper outlines a mechanical model that utilizes Hertzian contact theory to describe the interaction between the thin film and the substrate, and the conformal surface morphology and stress state were derived from minimizing the total energy of the island-substrate structure. The proposed formulations are verified through finite element methods and experiments, analyzing the effects of Young's modulus, in-plane size, and thickness of the "island" on its conformability. Therefore, this paper proposes a generic on-demand conformal design strategy that takes into account the complexity and hardness of the substrate. This study's findings will contribute to the development of conformal electronics that can be used in various fields, such as epidermal electronics, flexible robots, robot electronic skin, and aircraft smart skin. [Display omitted] [ABSTRACT FROM AUTHOR]

Indentation has become a promising tool to characterize the mechanical parameters of materials. In this work, herein, spherical indentations on elastic‐perfectly plastic materials and strain‐hardening materials are investigated through finite‐element method (FEM) simulations. A new method to extract the yield strength and strain‐hardening exponent from spherical indentation is proposed. The deviation of nominal contact pressure from Hertzian prediction is used as an indicator to determine the plastic parameters. The difference between Hertzian contact pressure and real contact pressure is also investigated for the estimation of contact radius during indentation process. Herein, a more convenient approach is provided in this analysis to directly determine the mechanical parameters of elastic–plastic materials from spherical indentation tests. Validation of this method is presented in the form of a comparison between analytical stress–strain relationships and corresponding curves obtained via iterative FEM simulations of the indentation process. No experimental data are involved in this validation. [ABSTRACT FROM AUTHOR]

Hertzian formulas are commonly used for the evaluation of deformation and pressure distribution of non-conformal and slightly conformal mechanical pairs to estimate component stiffness and durability. For the sake of simplicity, their use is extended even to those cases in which Hertz's hypotheses do not hold. This paper summarizes Hertz's theory and compares the results obtained with theoretical and finite element analysis of the point contact of non-conformal and conformal pairs made of spheres, caps, and spherical seats. This study was motivated by the non-Hertzian behavior of a tilting pad bearing ball-and-socket pivot conforming contact observed by the authors in previous experiments. In particular, the displacement and force relation were investigated by varying the geometrical parameters, the materials, the boundary conditions, and the friction coefficient. In the case of non-conformal contact, the parameter variations had negligible effect in agreement with Hertz's theory while for conformal contact, the cap and seat height and width and the relative clearance were the most influential parameters on the non-Hertzian behavior. These novel results indicate that in conformal pairs, such as for tilting pad bearing ball-and-socket pivots, whenever Hertz's hypotheses are not satisfied and the assessment of contact stiffness is crucial, Hertzian formulas should not be applied as done in common practice, instead more accurate numerical or experimental evaluation should be made. [ABSTRACT FROM AUTHOR]

The goal of this study was to explore the self-guided machining mechanism of boring and trepanning association (BTA) deep hole drilling and realize precise control of the machining quality. The motion analysis method was used to analyze the center motion trajectory of the drill during the entrance, and the self-guiding mechanism and hole-forming mechanism of BTA deep hole drilling were revealed. Considering the bending deformation of the drilling tube and the tool structure parameters, according to the elastic-plastic deformation theory and Hertzian contact theory, a novel analytical model of the extrusion contact between the guide pads and the hole wall of the BTA deep hole drilling was established for the theoretical prediction of the extrusion deformation and the machining hole diameter. Combined with the finite element method (FEM) simulation model, the variation law of the contact inclination angle, contact stress, and extrusion deformation of the guide pads and the hole wall with the drilling conditions were studied. The total extrusion deformation between the guide pad and the hole wall was between 10 and 50 μm. The maximum error between the FEM simulation results and the test results was 18.1%, and the maximum error between the analytical model results and the test results was 23.6%. The simulation and experimental results showed that the established extrusion contact model could accurately predict the extrusion deformation of the hole wall and the machining hole diameter. [ABSTRACT FROM AUTHOR]

In rolling or gear contacts, truncation of the contact ellipse can occur, for example, when an undercut extends into the contact area. For an elastic calculation approach, the edge constitutes a mathematical singularity, which is revealed by a theoretically infinitely high pressure peak. However, when elastic–plastic material behavior is taken into account, the pressure peak is limited by local hardening and yielding of the material, leading to plastic deformations. As a result, those calculations are rather challenging and the results partly unexpected due to the discontinuity contained in the geometry. Nevertheless, to the authors' knowledge, hardly any published studies exist on elastic–plastic simulations of truncated contact ellipses. Therefore, a numerical study concerning the contact of a rigid ball with an elastic–plastic plane is presented. Due to an undercut in the plane, a quarter of the theoretical Hertzian contact ellipse is cut off. The aim of the study is to investigate the influence of the undercut angle on the pressure distribution and the elastic and plastic deformation at the edge. The use of FEM shows that the undercut angle has a significant effect on the characteristics of the contact. The results obtained using FEM are then used as a reference for comparison with a semi-analytical method (SAM). It is shown that the SAM, based on the half-space, provides comparable results only for very small undercut angles. [ABSTRACT FROM AUTHOR]

• Achieved accurate calculation of contact force for anti-backlash beveloid gears. • Proposed a novel method for characterizing double-sided contact phenomena. • Considering the load-dependence of hertzian contact stiffness. • The proposed method is universally applicable to all double-sided contact gears. Double-sided contact is a typical phenomenon in anti-backlash gears. In the study of backlash elimination in gears, it is essential to accurately assess the contact forces on the backside. An analytical model for determining these contact forces in anti-backlash beveloid gears has been introduced, utilizing the Minimum Potential Energy Principle (MPEP). This model accounts for both axial preload and back-side contact. A novel approach has been developed to describe the meshing behavior on both the drive- and back-side, derived from an analysis of the relationship between back- and drive-side contact in beveloid gears. An investigation of the contact force distribution has been conducted, focusing on the impact of design parameters. Comparative analysis with the Finite Element Method (FEM) validates the capability of the proposed model to accurately compute the time-varying asymmetric contact forces experienced by beveloid gears under the influence of axial loading. [ABSTRACT FROM AUTHOR]

This work investigated the elastic responses of a composite laminate shell subjected to a transverse low-velocity impact. The governing equation based on the equations of motion of both the impactor and target was developed to detetrmine the impact force. The displacement of the shell subjected to unit impulse loading was solved using the finite element method. A non-linear differential equation in terms of the indentation depth was derived by incorporating the Hertzian contact law and theory of convolution. Runge-Kutta method was employed to solve the non-linear integro-differential equation, leading to the determination of the impact force at the point of contact between the impactor and the composite shell. The elastic responses including the displacement and stress of the composite laminate shell were evaluated using the finite element method by exerting the impact force on the apex of the composite shell. Present approach was verified with the analytical, experimental and numerical results reported in the existing literatures. The influences of stacking sequence of the composite laminate shell on the impact responses were examined through a series of parametric studies. In addition, impact responses of the spherical shells with different materials such as steel, aluminum and glass were studied. [ABSTRACT FROM AUTHOR]

• A novel method for the gear mesh stiffness calculation of plastic gear pair is established. • The influences of meshing deformation on the mesh behavior of plastic gear pair are investigated. • An iterative algorithm is utilized for the accurate calculation of gear mesh stiffness. • The proposed method is verified by the finite element method. The accurate calculation of the mesh stiffness for a plastic gear pair is significant for analyzing its transmission performance. During the meshing process, factors such as gear tooth meshing deformation and thermal effect will cause variations of the meshing position and tooth load particularly for plastic gears. These increase the difficulty for the accurate calculation of the gear mesh stiffness for plastic gear pair. To address this issue, the instantaneous gear tooth meshing deformation is obtained based on the potential energy method. Then, the effects of the above factors on the contact condition of a meshing tooth pair are analyzed, based on which the actual mesh position is accurately obtained via an iterative algorithm. Under the commonly-used elastic contact assumption, the contact stiffness at the new meshing position is calculated based on the Hertzian contact theory, and the algorithm of the mesh stiffness calculation for a plastic gear pair is derived by analyzing the influence of the elastic approach of meshing tooth on load distribution mechanism of gear pair. Compared with previous analytical methods, the proposed algorithm for mesh stiffness calculation shows higher accuracy, and it can also properly analyze the effect of load and other parameters on the mesh behavior of plastic gear pair, which can provide a theoretical basis for the performance analysis of plastic gear transmission system. [ABSTRACT FROM AUTHOR]

Hertzian formulas are commonly used for the evaluation of deformation and pressure distribution of non-conformal and slightly conformal mechanical pairs to estimate component stiffness and durability. For the sake of simplicity, their use is extended even to those cases in which Hertz’s hypotheses do not hold. This paper summarizes Hertz’s theory and compares the results obtained with theoretical and finite element analysis of the point contact of non-conformal and conformal pairs made of spheres, caps, and spherical seats. This study was motivated by the non-Hertzian behavior of a tilting pad bearing ball-and-socket pivot conforming contact observed by the authors in previous experiments. In particular, the displacement and force relation were investigated by varying the geometrical parameters, the materials, the boundary conditions, and the friction coefficient. In the case of non-conformal contact, the parameter variations had negligible effect in agreement with Hertz’s theory while for conformal contact, the cap and seat height and width and the relative clearance were the most influential parameters on the non-Hertzian behavior. These novel results indicate that in conformal pairs, such as for tilting pad bearing ball-and-socket pivots, whenever Hertz’s hypotheses are not satisfied and the assessment of contact stiffness is crucial, Hertzian formulas should not be applied as done in common practice, instead more accurate numerical or experimental evaluation should be made.

• A comprehensive stiffness model of intermediate bearing is presented. • A reduced model of dual rotor-bearing-casing coupling system is developed. • The effects of typical parameters on the vibration of the system are discussed. • The mechanism of the comprehensive stiffness and system vibration is revealed. This paper focuses on the vibrational properties of a dual rotor-casing coupled system with nonlinear clearance in the intermediate bearing, considering both the oil film stiffness and Hertzian contact stiffness between rolling elements and raceways. A comprehensive stiffness model for the intermediate bearing has been developed based on elastohydrodynamic lubrication (EHL) and Hertz contact theory. Subsequently, a dynamical model of the dual rotor-bearing-casing system is established using the finite element method, thereby verifying the feasibility of simulating the casing with beam elements. The dimensionality of the system equation is reduced using the fixed-interface component mode synthesis (CMS) method, and the resulting reduced-dimensionality equation is solved using the improved Newmark- β method. The effects of casing support, rotational speed, and radial clearance on the vibration characteristics of the system are investigated. Then, the comprehensive stiffness and coupled vibration characteristics of the system are analyzed to elucidate its intrinsic mechanism. Finally, the contact characteristics within the intermediate bearing under dynamic load are also studied. The results indicate that the support stiffness of the casing has a more significant impact on the second resonance caused by both the inner and outer rotors. The system is prone to experiencing varying compliance (VC) resonance at low rotational speeds. The excessive bearing clearance leads to complex vibrational characteristics of the system, making it challenging to predict its motion. The impact of minor changes in stiffness on system vibration is small when the comprehensive stiffness is large. At this time, the limited effect of oil film stiffness allows it to be disregarded in terms of comprehensive stiffness. Furthermore, the speed significantly influences the contact characteristics within the intermediate bearing under the unbalanced force of the rotor and gravity. [ABSTRACT FROM AUTHOR]

• A semianalytical Hertzian frictional contact model in 2D is developed with a penalty factor. • The penalty factor increases with contact width and Poisson's ratio, and is bounded between 0 and 1. • The Hertzian contact stresses and partial slip effects are explicitly considered. • The proposed contact model is validated with finite element analyses and DEM simulations. The Hertzian contact model is prominent for characterizing the contact behaviors of particles in three dimensions (3D), while its two-dimensional (2D) version in the tangential direction has not been well-established yet. In this work, a semianalytical Hertzian frictional contact model in 2D is developed, with an analytical solution for the normal contact behavior and a semianalytical solution with a variable penalty factor for the tangential contact behavior. Numerical analyses with finite element simulations are performed to characterize the penalty factor and validate the proposed contact model. The results show that the penalty factor increases with the contact width and Poisson's ratio based on which an empirical equation of the penalty factor is provided. Using the penalty factor calculated from the empirical equation, the contact behaviors evaluated from the proposed contact model match fairly well with those of finite element simulations. The proposed contact model is implemented in a discrete element code. Quantitative analyses of a bi-axial compression test on polydispersed particles demonstrate the stability and effectiveness of the proposed contact model. The proposed contact model could be useful to the computational mechanics of particles in 2D and parallel-axis cylinders with strip contacts in 3D. [ABSTRACT FROM AUTHOR]

High levels of contact stress between mating teeth can damage the contact surface and hall structure of spur gears, driving research that has aimed to minimize this stress. This study analyzed the effects of the profile shift factor (x) on the contact stress between a pair of spur gear teeth. Five profile shift factors were considered, from x = 0 (standard spur gear) to x=0.2. For each case, theoretical results were calculated based on the Hertzian contact theory and ISOequations of contact stress and subsequently compared with results generated in the ANSYS Workbench software using the finite element method. Modal analysis was performed to compare the mode shape frequencies of all profile shift factor values. The harmonic responses indicate that the stresses generated by our geometry are less than the maximum material stress. [ABSTRACT FROM AUTHOR]

Bearing failure is one of the most important factors influencing performance, accuracy and reliability of rotating machineries. Bearing faults are commonly shown as the defects such as rolling body fracture, rolling body, and surface pitting, etc. Dynamic model of 6206 deep groove ball bearing with the above-mentioned bearing faults has been established by finite element method. Exponent Hardening Plasticity Cowper Symonds model related to strength and hardening coefficients is adopted for describing elastoplastic material model of rolling body. The smaller difference between simulated results obtained by EDM and theoretical results calculated by Hertzian point contact theory validates the reliability of explicit dynamic model established in this paper. Dynamic contact characteristics of rolling bearing with different faults such as rolling body fracture, rolling body peeling, and bearing pitting are investigated using explicit dynamic model above. By comparing contact characteristics of fault bearing with those of fault-free bearing, it provides a reference for fault diagnosis and failure prevention of rolling bearing. [ABSTRACT FROM AUTHOR]

Summary: This paper proposes an original adaptive refinement framework using radial basis function–generated finite differences method. Node distributions are generated with a Poisson disc sampling–based algorithm from a given continuous density function, which is altered during the refinement process based on the error indicator. All elements of the proposed adaptive strategy rely only on meshless concepts, which leads to great flexibility and generality of the solution procedure. The proposed framework is tested on four gradually more complex contact problems. First, a disc under pressure is considered and the computed stress field is compared to the closed‐form solution of the problem to assess the behaviour of the algorithm and the influence of free parameters. Second, a Hertzian contact problem is studied to analyse the proposed algorithm with an ad hoc error indicator and to test both refinement and derefinement. A contact problem, typical for fretting fatigue, with no known closed‐form solution is considered and solved next. It is demonstrated that the proposed methodology produces results comparable with finite element method without the need for manual refinement or any human intervention. In the last case, generality of the proposed approach is demonstrated by solving a three‐dimensional Boussinesq's problem. [ABSTRACT FROM AUTHOR]

Most piezoelectric energy harvesting research has focused on developing on-resonance harvesters that work at low frequencies, even though higher frequencies can generate more power. In addition, conventional resonant harvesters have low efficiency when the excitation frequency is away from resonance. Using mechanical impacts has the potential to improve the overall harvested energy since high frequencies are excited during impacts. Also, the presence of impacts reduces the influence of the base excitation frequency and the requirement to exactly match the resonance frequency. To take advantage of the higher frequency response, an impact energy harvester is designed and validated experimentally. The harvester consists of a cantilever beam with a piezoelectric patch attached to its base which impacts with a stiff object. The harvester is modelled using finite element analysis and a Hertzian contact law. The model is tested and validated in the laboratory using an in-house manufactured demonstrator. Good agreement with the experimental data is obtained, setting the basis for future optimisation of the harvester geometry and piezoelectric properties. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel model is established to analyze the loaded contact characteristics of PRSM. • The advantages of our methodology are shown by comparison with existing models. • The sensitivity weights of the parameters are identified using machine learning. • A preferred zone is constructed to optimize the geometric parameters. The performance of the planetary roller screw mechanism (PRSM) is directly determined by the mechanical behavior of the loaded contact. The traditional method based on a finite element modeling to describe the loaded contact characteristics (LCCs) is computationally expensive, while the use of Hertzian contact theory and the thread connection model results in a loss of computational accuracy. As a solution, this study aims to develop a semi-analytic modeling technique that can predict the LCCs of PRSM accurately and efficiently. To achieve this, the study first establishes a mathematical model using the spatial coordinate transformation theory to accurately describe the thread surface. The potential contact area is discretely divided using the differential geometry principle. Then, the linear deformation and nonlinear deformation are matched using node interpolation technique to obtain the accurate compliance of the potential contact area. Finally, the contact forces for all activated contact points are derived by a nonlinear iterative algorithm based on the influence coefficient method. The performance of the proposed model is verified by numerical examples. Further, the sensitivity weights of the geometric parameters to the LCCs are identified utilizing machine learning, and a preferred zone is also constructed to optimize these parameters. This study provides a valuable tool for evaluating and improving the LCCs of PRSM in engineering practice. [ABSTRACT FROM AUTHOR]

Clearance is a pivotal factor in determining the fatigue life of high-speed rolling bearings (HSRBs). As HSRBs naturally experience various defects, their clearance levels tend to rise. However, a clear understanding of the vibration caused by clearance is still lacking. To address this gap, a five-degree-of-freedom dynamics model for HSRBs is proposed. This model accounts for centrifugal force, gyroscopic moment, and time-varying contact angle. In addition, the proposed model incorporates asymptotic theory to describe the defect process and the time-varying contact force derived from the Hertzian point contact theory between rolling elements and raceways. Furthermore, the model considers the variations in load zone and rolling element velocity that arise due to clearance. Applying this model, the dynamic response of HSRBs with different level clearances is calculated. The model's correctness is verified by comparing the dynamic response with the finite element model results and data measured using a test rig built for aero-engine spindle bearing. The results demonstrate that the extent of the load zone shrinks as the clearance increases, although the reduction rate gradually slows down. Since the bearing is loaded only in the load zone, aggravated clearance causes rolling elements to slip in the non-load zone. The effect of clearance on contact force is significantly weaker pronounced than that of defects. These research findings provide a theoretical foundation for the analysis and performance prediction of HSRBs and have important reference values for their optimal design. [ABSTRACT FROM AUTHOR]

The present paper deals with linear and quadratic finite element approximations of the two and three-dimensional unilateral contact problems between two elastic bodies with nonmatching meshes. We propose a simple noninterpenetration condition on the displacements which is local as the well known node-to-segment and node-to-face conditions and accurate like the mortar approach. This condition consists of averaging locally on a few elements the noninterpenetration. We prove optimal convergence rates in 2D and 3D using various linear and quadratic elements. The Taylor patch test and the Hertzian contact test illustrate the theoretical results and show the capabilities of the method. [ABSTRACT FROM AUTHOR]

The mechanical behavior of multibody systems can be modeled with several numerical methods. One can mention the Multibody Dynamics (MBD), the Finite Element Method (FEM), the Discrete Element Method (DEM) among others, which have the common feature of solving for the dynamics of a system of rigid/flexible bodies. In this context, the mechanical contact interaction between bodies has to be considered in the model. First, one needs to adopt a strategy to seek for contact occurrence and, when it is detected, to evaluate and include contributions into the mathematical model. However, handling contacts in such models is not a straightforward task, as they can be numerous (depending on the number of bodies considered in the model) and complex, due to the particularities in the geometric shape that each body presents, influencing in contact detection and in its inclusion, as a contribution into the model. In this work, we propose an integrated framework for handling and managing the automatic contact detection between bodies within a whole complex multibody system. Both rigid and flexible bodies can be considered. Strategies such as MBD, FEM and DEM can be employed together with the proposed strategy. Pointwise contact interactions are modeled based on the geometric description of each body's boundary, with the aid of the master–master contact formulation. A hierarchy of bounding volumes for the collision detection is employed, ruling the creation of a contact–candidates pairs list, for which the Local Contact Problem (LCP) is solved — as a detailed determination for the contact pointwise location on local surface parameterizations, representing bodies' boundaries. As the contact interface, we employ a particular hybrid law that can represent a classical linear contact stiffness, Hertzian contact and other possibilities, together with a barrier to avoid penetration between bodies. We show applications of the technique involving general rigid polyhedra in contact with beam finite elements — as a FEM/DEM coupling, such as rolling rigid bodies, as a classical multibody dynamics application. The herein proposed strategy can be incorporated using distinct time-integration solvers, such as it is independent on MBD/FEM/DEM particularities. [ABSTRACT FROM AUTHOR]

This work experimentally demonstrates inter-modal targeted energy transfer (IMTET) in a cantilever beam system with vibro-impacts. IMTET is known to achieve non-resonant rapid energy transfer from low-to-high frequency structural modes in mechanical systems. While previous works have computationally demonstrated the efficacy of IMTET, the theory and methodology supporting IMTET still lacks experimental verification. To address this task, an experiment is constructed whereby a steel beam is clamped at one end and excited at the other, and steel tips with clearances anchored to a host fixture serve as vibro-impacts (VIs) which induce non-resonant energy redistribution within the modal space of the beam. The system is modeled as an Euler–Bernoulli cantilever beam which is discretized by the finite element method, and the VI forces are simulated by a single-sided dissipative Hertzian contact model. The time-responses, modal dissipation ratios, and characteristic decay times measured in the experiment are compared to the computational models to confirm the validity of the theoretical predictions. It is found for both the experiment and computational model that the VIs transfer energy from low frequency structural modes to high frequency ones which, in turn, results in a substantial reduction in the characteristic decay time and thus confirms the efficacy of IMTET in practice. The diverse potential applications of IMTET in engineering practice are then emphasized. • Vibro-impacts transfer energy from low-to-high modes for rapid energy dissipation. • The system is studied in computational and experimental domains. • Computational and experimental findings support inter-modal targeted energy transfer. [ABSTRACT FROM AUTHOR]

We compared the quasi-static and dynamic simulation responses on elastic-plastic deformation of advanced alloys using Finite element (FE) method with an explicit numerical algorithm. A geometrical model consisting of a cylinder-on-flat surface contact under a normal load and sliding motion was examined. Two aeroengine materials, Ti-6Al-4V and Super CMV (Cr-Mo-V) alloy, were employed in the FE analysis. The FE model was validated by comparative magnitudes of the FE-predicted maximum contact pressure variation along the contact half-width length with the theoretical Hertzian contact solution. Results show that the (compressive) displacement of the initial contact surface steadily increases for the quasi-static load case, but accumulates at an increasing rate to the maximum level for the dynamic loading. However, the relatively higher stiffness and yield strength of the Super CMV alloy resulted in limited deformation and low plastic strain when compared to the Ti-6Al-4V alloy. The accumulated equivalent plastic strain of the material point at the initial contact position was nearly a thousand times higher for the dynamic load case (for example, 6.592 for Ti-6Al-4V, 1.0 kN) when compared to the quasi-static loading (only 0.0072). During the loading step, the von Mises stress increased with a decreasing and increasing rate for the quasi-static and dynamic load case, respectively. A sudden increase in the stress magnitude to the respective peak value was registered due to the additional constraint to overcome the static friction of the mating surfaces during the sliding step. [ABSTRACT FROM AUTHOR]

In this paper a comparison was studied between mathematical modeling of CNG hybrid cylinder under impact. Impact resistance of hybrid material is analyzed using analytical modeling. Impact resistance against applied force is studied using Hertzian law which relates contact stiffness of wooden block and composite. Finite Element Analysis (FEA) for Low velocity impact (LVI) of wooden block on hybrid CNG cylinder is done for finding structural response parameters. 2 degree of freedom (2DOF) spring mass system is used for mathematical modeling of impact of wooden block on hybrid CNG cylinder. Stiffness values by analytical modeling are used in mathematical modeling for comparison with FEA. Results further show that values found by FEA and mathematical modeling are closely comparable. [ABSTRACT FROM AUTHOR]

Three-dimensional finite element analysis of physical-contact, multi-fiber optical connector was used to characterize fiber-to-fiber contact and support the development and validation of a semi-analytical model (SAM) for the contact force. This contact behavior is determined by the elastic deformation of the system components (ferrule, fibers, and bonding adhesive) and the classical Hertzian contact at the fiber tips – effects that ultimately define the axial compliance of the system. Two 3-D finite element models for a 12-fiber connector are constructed to study the contact of two connectors, and the specific numerical simulations are carried out to generate input data to SAM, confirm the main assumptions made in its development, and numerically validate the predictions for the contact force. These simulations mainly consider non-uniform fiber height profiles and different end-face fiber tip geometries characterized by their radius of curvature. The numerically validated SAM is then used to study some performance aspects of multi-fiber connectors as related to the required contact force, namely, finding fiber height profiles that require minimum contact force and evaluating the throughput of polishing processes assuming a target contact force. Predictions are supported by Monte Carlo simulations and associated with current profile geometry metrics. [ABSTRACT FROM AUTHOR]

Since computer controlled optical surfacing (CCOS) processes were proposed in the 1960s, many processes were developed for precision optics successfully. In this present work, a novel approach, the precessions process, is proposed and used for large segments fabrication. The removal function of the bonnet polisher based on velocity and pressure distribution, which are obtained from the geometry of the process tool-motion and Hertzian contact theory respectively, are simulated. A finite element analysis (FEA) model is constructed to optimize process parameters. At last, detailed experimental studies are carried out to verify the optimal parameters. [ABSTRACT FROM AUTHOR]

This paper presents theoretical foundations, numerical implementation and examples of application of a two-dimensional Discrete-Element bonded-particle Sea Ice model DESIgn. In the model, sea ice is represented as an assemblage of objects of two types: disk-shaped "grains", and semi-elastic bonds connecting them. Grains move on the sea surface under the influence of forces from the atmosphere and the ocean, as well as interactions with surrounding grains through a direct contact (Hertzian contact mechanics) and/or through bonds. The model has an option of taking into account quasi-three-dimensional effects related to space- and time-varying curvature of the sea surface, thus enabling simulation of ice breaking due to stresses resulting from bending moments associated with surface waves. Examples of the model's application to simple sea ice deformation and breaking problems are presented, with an analysis of the influence of the basic model parameters ("microscopic" properties of grains and bonds) on the large-scale response of the modeled material. The model is written as a toolbox suitable for usage with the open-source numerical library LIGGGHTS. The code, together with a full technical documentation and example input files, is freely available with this paper and on the Internet. [ABSTRACT FROM AUTHOR]

This paper presents the investigation of guided wave propagation in prestressed double-cylinder structure. Based on Hertzian contact theory, the interaction between two rods is treated as a plane strain problem and the stress state in the waveguide under the static load is obtained. The stress state is considered as a prestressed configuration for elastic wave propagation analysis in double cylindrical rods. The elastodynamic equation of the prestressed structure is established with the updated Lagrangian formulation and the wave finite element (WFE) method. Firstly, the equation is verified by the application on an aluminum rod compared with the Euler–Bernoulli beam theory. Then, dispersion curves for single rod and double cylindrical rods without prestress are computed. Besides, at the dimensionless frequency 0.25 the propagating modes in double cylindrical rods are identified with mode shapes and displacement vectors. The guided waves in double rods consist of the modes different from single rod. Particularly, there exist two kinds of torsional-like modes, one of which has a twist center and the other has two. The latter changes obviously with the increase of prestress in the waveguide. At low frequencies, torsional-like modes are very sensitive to the variation of prestress; in addition, the prestress configuration has little influence on propagating modes at mid-frequencies but some at high frequencies. [ABSTRACT FROM AUTHOR]

A general elliptical Hertzian contact, such as a ball rolling in a non-conforming groove or two non-orthogonal cylinders, is a universal phenomenon in engineering. A partial elliptical contact is formed by contact bodies under a normal force and a transverse force that is insufficient to cause complete sliding. A computational model based on the semi-analytical method is established to calculate the von Mises stress distribution. Furthermore, a parametric study on factors influencing the location of the maximum von Mises stress point, such as the coefficient of friction and stick zone ratio, is conducted. Results show that the location of the maximum von Mises stress point depends on the coefficient of friction f and stick zone ratio c. The von Mises stress increases significantly with the increasing coefficient of friction f. Moreover, the maximum von Mises stress point tends to occur at a subsurface when the stick ratio c increases. [ABSTRACT FROM AUTHOR]

In this work, the elasto-plastic contact of a cylinder against a flat surface is experimentally investigated and compared with the predictions obtained with a recently proposed finite element contact framework (Doca et al. (2014) [1] ). The analysis is performed for three different materials and includes all stages of deformation ranging from elastic Hertzian contact through elasto-plastic deformation to finite deformation plastic contact. The behaviors of the contact length and contact pressure are presented as well as the comparison between predicted and measured specimen profiles. The evolution of the effective plastic strain is also reported. The results clearly demonstrate the ability of the contact formulation to capture the behavior of the elasto-plastic contact of a cylinder against a flat surface that is experimentally observed. [ABSTRACT FROM AUTHOR]

Abstract: Unwanted vibration modes of a drillstring can result in inefficient drilling, and damage to the drillstring, bit, BHA components, MWD tools and mud motors. Bottom-hole assembly (BHA) configuration design, shock sub parameter tuning, and establishing drilling parameters such as rotary speed and weigh-on-bit can be improved using computer simulation of a drillstring and its vibration modes. Drilling tools are under development to apply axial vibrations for the purpose of overcoming drillstring-wellbore friction, facilitating cutting removal and improving the rate of penetration (ROP) of the bit. Predicting the effects (both desired and undesired) of such axial vibration generator tools is becoming increasingly important to industry. In this paper, the coupled nonlinear axial-transverse dynamics of the entire drillstring are modeled and lateral instabilities are qualitatively studied. The drillstring includes the pipes, a multi-span BHA with shock sub, and a force generator tool near the bit. The multi-span BHA model enables more accurate natural frequency prediction and multi-mode contact analysis of the drillstring and wellbore. The governing equations are obtained using the “Bypassing PDE׳s” method with the expanded Galerkin׳s method, which enables finding the symbolic solution of the governing equations. The effects of mud damping, driving torque, and spatially varying axial load are also included, along with nonlinearities due to geometry, axial stiffening, strain energy and Hertzian contact forces. Simulations reveal resonant frequencies and show the relative severity of the contact in each span of the BHA. The model features fast running time compared to a high-order finite element model against which it is validated. [Copyright &y& Elsevier]

Abstract: A new approach was developed for modeling the effect of the third body on fretting. This was accomplished using the combined finite-discrete element method (FDEM) in which the third body is analyzed as discrete elements while the first bodies are modeled using finite elements. This approach provides a link between large scale models which treat the mass of wear debris as a single or small number of bodies and small scale models which only study a control volume. The FDEM was used to analyze the behavior of third body particles between flat sliding surfaces. When the third body mass is composed of unconnected particles, it behaves as a Newtonian fluid, but this behavior ceases when the particles are connected into platelets. The FDEM was also used to study the behavior of third body particles inside a Hertzian line contact. As the number of particles and platelet size increase the load carried by the worn slip zone grows larger in relationship to the unworn stick zone. [Copyright &y& Elsevier]

To validate models of contact mechanics in low speed structural impact, slender rods were impacted in a drop tower, and measurements of the contact and vibration were compared to analytical and finite element (FE) models. The contact area was recorded using a novel thin-film transfer technique, and the contact duration was measured using electrical continuity. Strain gages recorded the vibratory strain in one rod, and a laser Doppler vibrometer measured speed. The experiment was modeled analytically on a one-dimensional spatial domain using a quasi-static Hertzian contact law and a system of delay differential equations. The three-dimensional FE model used hexahedral elements, a penalty contact algorithm, and explicit time integration. A small submodel taken from the initial global FE model economically refined the analysis in the small contact region. Measured contact areas were within 6 % of both models' predictions, peak speeds within 2 %, cyclic strains within 12 με (RMS value), and contact durations within 2 μs. The global FE model and the measurements revealed small disturbances, not predicted by the analytical model, believed to be caused by interactions of the non-planar stress wavefront with the rod's ends. The accuracy of the predictions for this simple test, as well as the versatility of the diagnostic tools, validates the theoretical and computational models, corroborates instrument calibration, and establishes confidence that the same methods may be used in experimental and computational study of contact mechanics during impact of more complicated structures. Recommendations are made for applying the methods to a particular biomechanical problem: the edge-loading of a loose prosthetic hip joint which can lead to premature wear and prosthesis failure. [ABSTRACT FROM AUTHOR]

An enhanced analytical approach is suggested for calculating three rolling element bear-ing loads Fx, Fy, and Fz as well as the two tilting moments My and Mz as a function of five relative race displacements: three translations dx, dy, and dz, and two tilting angles dθy and dθz. A full coupling between all these displacements and forces is considered. This approach is particularly recommended for programming the rolling element bearing behavior in any finite element analysis or multibody system dynamic tool, since only two nodes are considered: one for the inner race center, usually connected to a shaft, and another node for the outer race center, connected to the housing. Also, roller and race-way crown radii are considered, meaning that Hertzian point contacts stiffness can be used at low load with a smooth transition toward Hertzian line contact as the load increases. This approach can be used for describing any rolling element bearing type when neglecting centrifugal and gyroscopic effects and applying the approximation of a constant ball-race contact angle. Deep groove ball bearings (whose contact angle sign follows the sign of the applied bearing axial force) or other ball bearings or spherical roller bearing operating under large misalignment may not support such approximations. [ABSTRACT FROM AUTHOR]

Abstract: Hertzian cone cracks are nowadays a scholarly case making it possible to understand fracture of materials. However, the simulation of this physical phenomenon is not trivial and most theoretical models lead to the prediction of cone crack angles different from those observed experimentally. In the past, finite-element models have been developed based on a re-meshing procedure to explain this difference successfully, but with some limitations due the algorithms used. In this paper, we propose to use the X-FEM method to model Hertzian cone crack propagation with a 2D axisymmetric approach. The effect of various numerical parameters, such as mesh size or time step, is investigated and it is shown that they do not have a great impact on the crack angle result. The analysis of the stress field induced leads us to understand the difference in terms of cone crack angle based on the pre-existing stress field and those experimentally observed. As a conclusion, X-FEM is very efficient to reproduce faithfully several characteristics of the Hertzian cone crack phenomenon in a very simple manner. [Copyright &y& Elsevier]

Abstract: The purpose of this paper is to investigate a 3D finite element (FE) coupled train-track model for the numerical modelling of the ground induced vibration due to the passage of a single high speed train locomotive. The track components such as the sleepers, the ballast and the subgrade are represented by 20 noded brick elements. The rail is modelled by using 3D beam-column elements. A quarter train model is coupled to the 3D railway track model, through the interaction points between the wheels and the rail, based on the nonlinear Hertzian contact theory. A damping model, based on Rayleigh damping approach, is used. The 3D FE model is capable of simulating multi-layered ground and radiation damping by using viscous boundary conditions. Material nonlinearity, especially of the ballast and subgrade layers can be taken into account as appropriate. Numerical experiments are carried out, using the proposed 3D FE coupled train-track model, to study the train fundamental passing frequency effect on the dynamic railway track response for train speeds belonging to the subcritical, critical and supercritical ranges. The influence of the soil material damping is also investigated. The results clearly show an increase in track deflection with train speed. The material damping model allows a realistic prediction of the track vibration and train body dynamics at high speeds. [Copyright &y& Elsevier]

Combining musculoskeletal simulations with anatomical joint models capable of predicting cartilage contact mechanics would provide a valuable tool for studying the relationships between muscle force and cartilage loading. As a step towards producing multibody musculoskeletal models that include representation of cartilage tissue mechanics, this research developed a subject-specific multibody knee model that represented the tibia plateau cartilage as discrete rigid bodies that interacted with the femur through deformable contacts. Parameters for the compliant contact law were derived using three methods: (1) simplified Hertzian contact theory, (2) simplified elastic foundation contact theory and (3) parameter optimisation from a finite element (FE) solution. The contact parameters and contact friction were evaluated during a simulated walk in a virtual dynamic knee simulator, and the resulting kinematics were compared with measuredin vitrokinematics. The effects on predicted contact pressures and cartilage–bone interface shear forces during the simulated walk were also evaluated. The compliant contact stiffness parameters had a statistically significant effect on predicted contact pressures as well as all tibio-femoral motions except flexion–extension. The contact friction was not statistically significant to contact pressures, but was statistically significant to medial–lateral translation and all rotations except flexion–extension. The magnitude of kinematic differences between model formulations was relatively small, but contact pressure predictions were sensitive to model formulation. The developed multibody knee model was computationally efficient and had a computation time 283 times faster than a FE simulation using the same geometries and boundary conditions. [ABSTRACT FROM PUBLISHER]

In this investigation, the fretting wear phenomenon was investigated experimentally and analytically. For the analytical investigation, a combined finite discrete element model (FDEM) was developed to study the effects of displacement amplitude and normal force on fretting wear. The FDEM was used to investigate the wear of a fretting Hertzian line contact calculated using the Archard and dissipated energy wear theories. Although the FDEM results from each theory were in agreement, the dissipated energy approach more accurately predicted the wear volumes obtained from experimental measurements. A fretting wear test rig (FWTR) was used to verify and corroborate the results and conclusions of the numerical investigation. The results indicated that the dissipated energy equation better describes wear in fretting contacts than the Archard equation. An energy dissipation rate map was developed from the experimental results, showing the effect of normal force and displacement amplitude on frictional energy loss. The energy dissipation rate map was used to create a steady-state fretting wear map. [ABSTRACT FROM AUTHOR]

A study is performed on the influence of some typical railway vehicle and track parameters on the level of ground vibrations induced in the neighbourhood. The results are obtained from a previously validated simulation framework considering in a first step the vehicle/track subsystem and, in a second step, the response of the soil to the forces resulting from the first analysis. The vehicle is reduced to a simple vertical 3-dof model, corresponding to the superposition of the wheelset, the bogie and the car body. The rail is modelled as a succession of beam elements elastically supported by the sleepers, lying themselves on a flexible foundation representing the ballast and the subgrade. The connection between the wheels and the rails is realised through a non-linear Hertzian contact. The soil motion is obtained from a finite/infinite element model. The investigated vehicle parameters are its type (urban, high speed, freight, etc.) and its speed. For the track, the rail flexural stiffness, the railpad stiffness, the spacing between sleepers and the rail and sleeper masses are considered. In all cases, the parameter value range is defined from a bibliographic browsing. At the end, the paper proposes a table summarising the influence of each studied parameter on three indicators: the vehicle acceleration, the rail velocity and the soil velocity. It namely turns out that the vehicle has a serious influence on the vibration level and should be considered in prediction models. [ABSTRACT FROM AUTHOR]

We study the dynamic response of uniform granular chains composed of short cylindrical particles excited by an impulse. The particles in the chains are arranged with their axes orthogonal to the chain's axis, and the particles maintain a constant relative orientation angle. We study the formation and propagation of solitary waves in the chains varying the orientation angle ( α) between particles, and show tunability of the stress transfer as a function of α. We use the general Hertzian contact theory to model the interaction between particles. We compare experimental findings with theoretical predictions based on the long wavelength approximation, and with numerical predictions based on a one-dimensional discrete particle model, and on a three-dimensional finite element approach, finding good agreement. [ABSTRACT FROM AUTHOR]

A dental articulator is a mechanism which simulates the temporo-mandibular joint. The articulator is essential as it replicates the basic motions of the upper and lower mandibles, both revolve and translational motions. In the present paper the stresses from an articulator TMJ modelled as a bronze sphere into a cylindrical steel cavity are analyzed by two methods, first applying the Hertzian contact theory and then numerically, by means of finite element analysis using the simulation module in CATIA. [ABSTRACT FROM AUTHOR]

A computational approach is presented in this paper for the direct numerical simulation of 3D particulate flows. The given approach is based on the fictitious domain method, whereby the Discrete Element Method (DEM) and the Finite Element Method (FEM) are explicitly coupled for the numerical treatment of particle-fluid interactions. The particle properties are constitutively described by an adhesive viscbelastic model. To compute the hydrodynamic forces, a direct integration method is employed, where the fluid stresses are integrated over the particles' surfaces. For the purpose of verifying the presented approach, computational results are shown and compared with those of the literature. Finally, the method is applied for the simulation of an agglomeration example. [ABSTRACT FROM AUTHOR]