Capturing heat transfer for complex-shaped multibody contact problems, a new FDEM approach

This paper presents a new approach for the modelling of heat transfer in 3D discrete particle systems. Using a combined finite–discrete element (FDEM) method, the surface of contact is numerically computed when two discrete meshes of two solids experience a small overlap. Incoming heat flux and heat conduction inside and between solid bodies are linked. In traditional FEM (finite element method) or DEM (discrete element method) approaches, to model heat transfer across contacting bodies, the surface of contact is not directly reconstructed. The approach adopted here uses the number of surface elements from the penetrating boundary meshes to form a polygon of the intersection, resulting in a significant decrease in the mesh dependency of the method. Moreover, this new method is suitable for any sizes or shapes making up the particle system, and heat distribution across particles is an inherent feature of the model. This FDEM approach is validated against two models: a FEM model and a DEM pipe network model. In addition, a multi-particle heat transfer contact problem of complex-shaped particles is presented.

Developing of a Simscape Multibody Contact Library for Gothic Arc Ball Screws: A Three-Dimensional Model for Internal Sphere/Grooves Interactions

The Simscape Multibody software is a set of libraries and mechanical modeling and simulation tools for use with Simulink®. For what concerns the contact library, currently it contains only the models to describe impacts between simple geometries, such as spheres, cylinders and planes. When this environment is intended to be used to simulate the 3D dynamics of a system with a complex geometry, such as a ball screw, the built-in blocks are not sufficient. This paper presents a new contact library, containing blocks specifically designed to handle the contacts between a sphere and the two gothic arc helical grooves of a ball screw, as well as the interaction between adjacent spheres. The developed blocks are exploited to create a first case study dynamic model of a single nut not preloaded ball screw in presence of internal backlash. The results highlight the superiority of this multibody approach with respect to the quasi-static or lumped parameters models in terms of extracted information and understanding of the internal mechanics.

Advancement of Contact Dynamics Modeling for Human Spaceflight Simulation Applications

Pong is a new software tool developed at the NASA Johnson Space Center that advances interference-based geometric contact dynamics based on 3D graphics models. The Pong software consists of three parts: a set of scripts to extract geometric data from 3D graphics models, a contact dynamics engine that provides collision detection and force calculations based on the extracted geometric data, and a set of scripts for visualizing the dynamics response with the 3D graphics models. The contact dynamics engine can be linked with an external multibody dynamics engine to provide an integrated multibody contact dynamics simulation. This paper provides a detailed overview of Pong including the overall approach, modeling capabilities, which encompasses force generation to computational performance, and example applications.

Reduced-Order Modelling of Multibody Contact Problems: A Novel Semi-Analytic Method

In this paper we present a novel method to efficiently solve gear contact simulations in a flexible multi-body environment. Semi-analytical contact approaches have been recently used in Finite Element (FE) simulations for describing the displacement field in the contact zone and eliminating the need for highly refined FE meshes. In the proposed method, we integrate a semi-analytic strategy with a Model Order Reduction (MOR) scheme, which allows us to decrease further the reduced order model complexity as well as the computational burden. We validate the method against state-of-the-art MOR techniques, for both static and dynamic gear contact problems. Finally the results show how the presented method is able to more efficiently capture quantitatively the transmission error in case of spur geared transmission for different torque levels.

Differential-difference iterative domain decomposition algorithms for unilateral multibody contact problems of elasticity

Implicit two-point differential-difference parallel iterative domain decomposition algorithms are proposed to solve the multibody contact problems of elasticity. A program implementation of these algorithms based on the finite element approximations is made for the case of plane contact problems. The influence of the iterative parameters on the convergence rate of presented algorithms is investigated. The numerical efficiency of different two-point and one-point iterative algorithms is compared.

Multi Rigid-Body Contact Dynamics With Regularized Friction

A novel mathematical formulation in terms of a linear complementarity problem is introduced for multibody contact problems. In this approach, contacts are characterized based on kinematic constraints while the friction forces are simultaneously regularized and incorporated into the formulation. The variables of the resulting linear complementarity problem are only the normal forces. The main advantage of this formulation is a significant dimension reduction in the resulting linear complementarity problem in comparison with its counterpart formulations in the literature. Moreover, the dimension can be even further reduced by removing the velocity variables from the formulation. The proposed formulation is examined for benchmark examples yielding promising results.