scholarly journals Cosserat Elastoplastic Finite Elements for Masonry Structures

2014 ◽  
Vol 624 ◽  
pp. 131-138 ◽  
Author(s):  
Michele Godio ◽  
Ioannis Stefanou ◽  
Karam Sab ◽  
Jean Sulem
Keyword(s):  
Finite Elements ◽  
Projection Algorithm ◽  
Elastic Plates ◽  
Discrete Elements ◽  
Backward Euler ◽  
Out Of Plane ◽  
Evolution Laws ◽  
Definition Of ◽  
Closest Point Projection ◽  
Point Projection

A Finite Elements formulation previously developed for Cosserat elastic plates, has been extended herein to the elastoplastic framework. Material non-linearities are taken into account through the implementation of a backward-Euler closest-point-projection algorithm, for which the definition of non-smooth yield loci and non-associated plastic potentials and evolution laws is made possible. An existing homogenized elastic constitutive model and a set of yield criteria for the out-of-plane behaviour of block-masonry are implemented in the code and their validity is discussed based on the comparison with Discrete Elements simulations. The comparison is carried out in both the static and the dynamic regime.

Green Schools as Teaching Tools

2015 ◽  
pp. 155-170
Author(s):  
Charles F. Carrick ◽  
Douglas B. Caywood
Keyword(s):  
Background Information ◽  
Discrete Elements ◽  
Green Schools ◽  
Teaching Activities ◽  
Working Definition ◽  
School Programs ◽  
Subject Areas ◽  
Green School ◽  
Definition Of ◽  
K 12

This chapter is meant to serve as both a resource and as an aid for K-12 teachers who are interested in incorporating the philosophy and various aspects of the green school into their day-to-day teaching activities. A working definition of green schools and a summary of their benefits are presented as background information for teachers unfamiliar with the movement. Suggested steps for greening schools and classrooms are provided for those who may be interested in advancing the concept in their particular situations. Throughout the chapter, the school is highlighted as a laboratory for practicing conservation. To that end, discrete elements of green design are presented as suggested subject areas. Successful green school programs are identified as an additional resource. Finally, suggested green activities for the classroom are provided for interested instructors.

Improving the 3D Finite-Discrete Element Method and Its Application in the Simulation of Wheel–Sand Interactions

2018 ◽  
Vol 15 (07) ◽  
pp. 1850059 ◽  
Author(s):  
Chunlai Zhao ◽  
Mengyan Zang ◽  
Shunhua Chen ◽  
Zumei Zheng
Keyword(s):  
Finite Elements ◽  
Discrete Element Method ◽  
Size Distribution ◽  
Sphere Packing ◽  
Discrete Element ◽  
Numerical Results ◽  
Contact Detection ◽  
Discrete Elements ◽  
Contact Algorithm ◽  
Packing Algorithm

An efficient sphere-packing algorithm named hierarchical generation method (HGM) is developed. The method is capable of efficiently generating spheres with a specific size distribution in a given geometric domain. Moreover, an improved contact algorithm for contact detection between spherical discrete elements and hexahedron finite elements (INTS) is presented. The algorithm is also suitable for simulating complex wheel–sand interactions. By using the developed algorithm, the running behaviors of a chevron tread-pattern wheel on a sand bed are simulated. The sand bed model is established by HGM and wheel–sand interactions are simulated using INTS. Numerical results validate the feasibility of the proposed method in the simulation of wheel–sand interactions.

Dynamic Effects in Stress Analysis for Discrete Elements Modeling: Application to Masonry

2005 ◽  
Author(s):  
Claude Bohatier ◽  
Brahim Chetouane ◽  
Marc Vinches
Keyword(s):  
Stress Tensor ◽  
Relative Weight ◽  
Load Level ◽  
Discrete Element Modelling ◽  
Dynamic Effects ◽  
Discrete Elements ◽  
A Cell ◽  
Definition Of ◽  
Dynamic Excitations ◽  
Final Expression

The discrete element modelling allows the study of the mechanical behaviour of a collection of solids, submitted to dynamic excitations. The proposed definition of a stress tensor concerns a cell constituted of its kernel, and its neighbouring solids. We demonstrate that taking into account the inertial effects allows the symmetry of the stress tensor. The relative weight of the centrifugal effects remaining in the final expression of the stress tensor is evaluated in order to determine whether or not it has to be taken into account, depending on the application. The proposed definition allows the definition of the load level on different parts of the discontinuous structure. Applications to real masonry cases are presented.

scholarly journals Simulation Informed CAD for 3D Nanoprinting

Micromachines ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 8 ◽  
Author(s):  
Jason D. Fowlkes ◽  
Robert Winkler ◽  
Eva Mutunga ◽  
Philip D. Rack ◽  
Harald Plank
Keyword(s):  
Analytical Model ◽  
Computer Aided Design ◽  
Critical Mass ◽  
Three Dimensional ◽  
Three Dimensional Objects ◽  
Non Linear ◽  
Out Of Plane ◽  
Digital Scanning ◽  
Definition Of ◽  
Bending Nanowires

A promising 3D nanoprinting method, used to deposit nanoscale mesh style objects, is prone to non-linear distortions which limits the complexity and variety of deposit geometries. The method, focused electron beam-induced deposition (FEBID), uses a nanoscale electron probe for continuous dissociation of surface adsorbed precursor molecules which drives highly localized deposition. Three dimensional objects are deposited using a 2D digital scanning pattern—the digital beam speed controls deposition into the third, or out-of-plane dimension. Multiple computer-aided design (CAD) programs exist for FEBID mesh object definition but rely on the definition of nodes and interconnecting linear nanowires. Thus, a method is needed to prevent non-linear/bending nanowires for accurate geometric synthesis. An analytical model is derived based on simulation results, calibrated using real experiments, to ensure linear nanowire deposition to compensate for implicit beam heating that takes place during FEBID. The model subsequently compensates and informs the exposure file containing the pixel-by-pixel scanning instructions, ensuring nanowire linearity by appropriately adjusting the patterning beam speeds. The derivation of the model is presented, based on a critical mass balance revealed by simulations and the strategy used to integrate the physics-based analytical model into an existing 3D nanoprinting CAD program is overviewed.

scholarly journals Definition of a P-interpolating space of hierarchical bases of finite elements on the pyramid

2014 ◽  
Vol 460 ◽  
pp. 174-204
Author(s):  
Cedric M.A. Ayala Bravo ◽  
Renato Pavanello ◽  
Philippe R.B. Devloo ◽  
Jorge L.D. Calle
Keyword(s):  
Finite Elements ◽  
Hierarchical Bases ◽  
Definition Of
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