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Micromechanical back-analysis of laboratory tests on rock
Published in G.N. Pande, S. Pietruszczak, H.F. Schweiger, Numerical Models in Geomechanics, 2020
L. te Kamp, H. Konietzky, P. Blümling, K. Ando, J.C. Mayor
The simplest contact model is the linear contact stiffness model. For a contact formed by two entities A and B with the unit normal ni the normal contact force Fin is related to the normal displacement Un via the normal contact stiffness, which is calculated as the average of the normal stiffnesses kn of A and B: Fin=(kn[A]kn[B]kn[A]+kn[B])Unni
Simplified model of a RC slab impacted by a block
Published in Günther Meschke, René de Borst, Herbert Mang, Nenad Bićanić, Computational Modelling of Concrete Structures, 2020
P. Perrotin, F. Delhomme, M. Mommessin, J-P Mougin
The contact between the block and the slab is defined by a contact element called “Contact42”. This element has five nodes with three degrees of freedom at each node: translations in the nodal x, y, and z directions. Contact occurs when the contact node penetrates the target base. Elastic Coulomb friction and rigid Coulomb friction are allowed, where sliding is along the target base. A normal contact stiffness, KN, is used in the penalty function method to determine contact forces.
Component model synthesis using model updating with neural networks
Published in Mechanics of Advanced Materials and Structures, 2023
Heejun Sung, Seongmin Chang, Maenghyo Cho
In general, the main parameters for model updating include not only the density and Young’s modulus of the bolt and washer models, but also the contact properties. In this study, no consideration was given to bolt loosening or breakage, and such an absence of bolt loosening or breakage was considered to reflect the dynamic behavior most accurately (modally equivalent model) when perfect fastening was achieved. As the assembly conditions, tangent and normal behaviors were also taken into account. From our current calculations, we found no significant effect of the tangential behaviors on the friction coefficient, slip rate, contact pressure, but a significant effect of the normal contact stiffness. The normal contact stiffness was used as an input parameter for training. The two parts of the present tank bracket model were each constructed to be modally equivalent to the experimental model. By using the CNN function trained by using the density and Young's modulus of each part as parameters, it was possible to construct a modally equivalent model. Similarly, in the assembly process, a CNN function was constructed using the density and Young's modulus of the bolt assembly structure, but this function was not sufficiently good. In order to build a modally equivalent model of the bolt assembly structure, a function of the CNN using the normal stiffness coefficients of the bolt assembly was employed as a parameter.
Particle contact characteristics of coarse-grained soils under normal contact
Published in European Journal of Environmental and Civil Engineering, 2018
Zhao Cheng, Hou Rui, Zhou Jian
In this study, it was assumed that (1) the normal forces measured in the normal contact experiment all acted on the contact points, (2) particle deformation could be neglected, and (3) all normal displacement was caused by erosion of the contact point; that is, the normal displacement measured in the experiment was equal to the relative displacement between the particles. The normal contact stiffness of the contact point was defined as the ratio of the particle normal contact force to the relative particle normal displacement (normal force/normal displacement).
Theoretical and Experimental Study on Normal Contact Stiffness of Plane Joint Surfaces With Surface Texturing
Published in Tribology Transactions, 2023
Chaochao Yin, Haihong Huang, Dan Zhou, Zhifeng Liu
For the textured specimens with different surface roughness Sa, the relationships of predictions of the proposed model and experimental data are shown in Fig. 10. As surface roughness decreases, the normal contact stiffness gradually increases for a fixed normal load. The reason is that the real contact area gradually increases as the roughness of rough surface decreases for the rough surfaces contact. The normal contact stiffness is closely related to the real contact area.