eprintid: 2763
rev_number: 10
eprint_status: archive
userid: 56
dir: disk0/00/00/27/63
datestamp: 2015-10-08 08:03:17
lastmod: 2015-10-08 08:04:30
status_changed: 2015-10-08 08:03:17
type: article
metadata_visibility: show
creators_name: Bemporad, Alberto
creators_name: Paggi, Marco
creators_id: alberto.bemporad@imtlucca.it
creators_id: marco.paggi@imtlucca.it
title: Optimization algorithms for the solution of the frictionless normal contact between rough surfaces
ispublished: pub
subjects: TJ
divisions: CSA
full_text_status: public
keywords: Unilateral contact problem; Frictionless normal contact; Quadratic programming; Optimization algorithms; Boundary element method; Roughness
abstract: This paper revisits the fundamental equations for the solution of the frictionless unilateral normal contact problem between a rough rigid surface and a linear elastic half-plane using the boundary element method (BEM). After recasting the resulting Linear Complementarity Problem (LCP) as a convex quadratic program (QP) with nonnegative constraints, different optimization algorithms are compared for its solution: (i) a Greedy method, based on different solvers for the unconstrained linear system (Conjugate Gradient CG, Gauss–Seidel, Cholesky factorization), (ii) a constrained CG algorithm, (iii) the Alternating Direction Method of Multipliers (ADMM), and (iv) the Non-Negative Least Squares (NNLS) algorithm, possibly warm-started by accelerated gradient projection steps or taking advantage of a loading history. The latter method is two orders of magnitude faster than the Greedy CG method and one order of magnitude faster than the constrained CG algorithm. Finally, we propose another type of warm start based on a refined criterion for the identification of the initial trial contact domain that can be used in conjunction with all the previous optimization algorithms. This method, called cascade multi-resolution (CMR), takes advantage of physical considerations regarding the scaling of the contact predictions by changing the surface resolution. The method is very efficient and accurate when applied to real or numerically generated rough surfaces, provided that their power spectral density function is of power-law type, as in case of self-affine fractal surfaces.
date: 2015-09
date_type: published
publication: International Journal of Solids and Structures
volume: 69-70
publisher: Elsevier
pagerange: 94-105
id_number: 10.1016/j.ijsolstr.2015.06.005
refereed: TRUE
issn: 0020-7683
official_url: http://www.sciencedirect.com/science/article/pii/S0020768315002693
funders: European Research Council
projects: ERC StG CA2PVM
citation:   Bemporad, Alberto and Paggi, Marco  Optimization algorithms for the solution of the frictionless normal contact between rough surfaces.  International Journal of Solids and Structures, 69-70.  pp. 94-105.  ISSN 0020-7683      (2015)  
document_url: http://eprints.imtlucca.it/2763/1/1506.00532v1.pdf