scholarly journals Stability and branching of stationary rotations in a planar problem of motion of mutually gravitating triangle and material point

2016 ◽  
pp. 179-196
Author(s):  
A.A. Burov ◽  
◽  
V. Nikonov ◽  
Keyword(s):  
Material Point ◽  
Planar Problem

Defects in Crystals

1968 ◽  
Vol 26 ◽  
pp. 244-245
Author(s):  
Kenneth R. Lawless
Keyword(s):  
Electron Microscope ◽  
Point Defects ◽  
Surface Defects ◽  
Chemical Properties ◽  
Material Point ◽  
Crystal Defects ◽  
Defects In Crystals ◽  
Irradiation Effects ◽  
Normal Lattice ◽  
Line Defects

One of the most important applications of the electron microscope in recent years has been to the observation of defects in crystals. Replica techniques have been widely utilized for many years for the observation of surface defects, but more recently the most striking use of the electron microscope has been for the direct observation of internal defects in crystals, utilizing the transmission of electrons through thin samples.Defects in crystals may be classified basically as point defects, line defects, and planar defects, all of which play an important role in determining the physical or chemical properties of a material. Point defects are of two types, either vacancies where individual atoms are missing from lattice sites, or interstitials where an atom is situated in between normal lattice sites. The so-called point defects most commonly observed are actually aggregates of either vacancies or interstitials. Details of crystal defects of this type are considered in the special session on “Irradiation Effects in Materials” and will not be considered in detail in this session.

The kinematics of a point particle

2018 ◽  
Author(s):  
Nathalie Deruelle ◽  
Jean-Philippe Uzan
Keyword(s):  
Internal Structure ◽  
Proper Time ◽  
World Line ◽  
Point Particle ◽  
Material Point ◽  
Spatial Extent ◽  
Geometric Representation ◽  
Mathematical Result ◽  
Point Particles ◽  
The World

This chapter discusses the kinematics of point particles undergoing any type of motion. It introduces the concept of proper time—the geometric representation of the time measured by an accelerated clock. It also describes a world line, which represents the motion of a material point or point particle P, that is, an object whose spatial extent and internal structure can be ignored. The chapter then considers the interpretation of the curvilinear abscissa, which by definition measures the length of the world line L representing the motion of the point particle P. Next, the chapter discusses a mathematical result popularized by Paul Langevin in the 1920s, the so-called ‘Langevin twins’ which revealed a paradoxical result. Finally, the transformation of velocities and accelerations is discussed.

scholarly journals Advanced soft robot modeling in ChainQueen

Robotica ◽  
2021 ◽  
pp. 1-31
Author(s):  
Andrew Spielberg ◽  
Tao Du ◽  
Yuanming Hu ◽  
Daniela Rus ◽  
Wojciech Matusik
Keyword(s):  
Application Programming Interface ◽  
Material Point ◽  
Soft Robotics ◽  
Soft Robot ◽  
Inference Control ◽  
Simulation And Optimization ◽  
Efficient Simulation ◽  
Application Programming ◽  
Robot Modeling ◽  
Programming Interface

Abstract We present extensions to ChainQueen, an open source, fully differentiable material point method simulator for soft robotics. Previous work established ChainQueen as a powerful tool for inference, control, and co-design for soft robotics. We detail enhancements to ChainQueen, allowing for more efficient simulation and optimization and expressive co-optimization over material properties and geometric parameters. We package our simulator extensions in an easy-to-use, modular application programming interface (API) with predefined observation models, controllers, actuators, optimizers, and geometric processing tools, making it simple to prototype complex experiments in 50 lines or fewer. We demonstrate the power of our simulator extensions in over nine simulated experiments.

scholarly journals Un-jamming due to energetic instability: statics to dynamics

2021 ◽  
Vol 23 (4) ◽  
Author(s):  
Stefan Luding ◽  
Yimin Jiang ◽  
Mario Liu
Keyword(s):  
Granular Matter ◽  
Numerical Data ◽  
Soft Materials ◽  
Material Point ◽  
Solid States ◽  
Granular Gas ◽  
Granular Solid Hydrodynamics ◽  
Particle Simulations ◽  
Points Of View ◽  
Deformation Modes

Abstract Jamming/un-jamming, the transition between solid- and fluid-like behavior in granular matter, is an ubiquitous phenomenon in need of a sound understanding. As argued here, in addition to the usual un-jamming by vanishing pressure due to a decrease of density, there is also yield (plastic rearrangements and un-jamming that occur) if, e.g., for given pressure, the shear stress becomes too large. Similar to the van der Waals transition between vapor and water, or the critical current in superconductors, we believe that one mechanism causing yield is by the loss of the energy’s convexity (causing irreversible re-arrangements of the micro-structure, either locally or globally). We focus on this mechanism in the context of granular solid hydrodynamics (GSH), generalized for very soft materials, i.e., large elastic deformations, employing it in an over-simplified (bottom-up) fashion by setting as many parameters as possible to constant. Also, we complemented/completed GSH by using various insights/observations from particle simulations and calibrating some of the theoretical parameters—both continuum and particle points of view are reviewed in the context of the research developments during the last few years. Any other energy-based elastic-plastic theory that is properly calibrated (top-down), by experimental or numerical data, would describe granular solids. But only if it would cover granular gas, fluid, and solid states simultaneously (as GSH does) could it follow the system transitions and evolution through all states into un-jammed, possibly dynamic/collisional states—and back to elastically stable ones. We show how the un-jamming dynamics starts off, unfolds, develops, and ends. We follow the system through various deformation modes: transitions, yielding, un-jamming and jamming, both analytically and numerically and bring together the material point continuum model with particle simulations, quantitatively. Graphic abstract

scholarly journals A Hybrid Material Point Method for Frictional Contact with Diverse Materials

2019 ◽  
Vol 2 (2) ◽  
pp. 1-24 ◽  
Author(s):  
Xuchen Han ◽  
Theodore F. Gast ◽  
Qi Guo ◽  
Stephanie Wang ◽  
Chenfanfu Jiang ◽  
...  
Keyword(s):  
Hybrid Material ◽  
Frictional Contact ◽  
Material Point Method ◽  
Material Point ◽  
Point Method

Three-dimensional face stability analysis of shallow tunnels using numerical limit analysis and material point method

2021 ◽  
Vol 112 ◽  
pp. 103904
Author(s):  
Fabricio Fernández ◽  
Jhonatan E.G. Rojas ◽  
Eurípedes A. Vargas ◽  
Raquel Q. Velloso ◽  
Daniel Dias
Keyword(s):  
Stability Analysis ◽  
Limit Analysis ◽  
Three Dimensional ◽  
Material Point Method ◽  
Material Point ◽  
Point Method ◽  
Face Stability ◽  
Shallow Tunnels ◽  
Dimensional Face

scholarly journals Dam Breach Simulation with the Material Point Method

Computation ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 8
Author(s):  
Chendi Cao ◽  
Mitchell Neilsen
Keyword(s):  
Material Point Method ◽  
Mixture Theory ◽  
Material Point ◽  
Point Method ◽  
Internal Erosion ◽  
Dam Breach ◽  
New Model ◽  
Hencky Strain ◽  
The Impact ◽  
Soil And Water

Dam embankment breaches caused by overtopping or internal erosion can impact both life and property downstream. It is important to accurately predict the amount of erosion, peak discharge, and the resulting downstream flow. This paper presents a new model based on the material point method to simulate soil and water interaction and predict failure rate parameters. The model assumes that the dam consists of a homogeneous embankment constructed with cohesive soil, and water inflow is defined by a hydrograph using other readily available reach routing software. The model uses continuum mixture theory to describe each phase where each species individually obeys the conservation of mass and momentum. A two-grid material point method is used to discretize the governing equations. The Drucker–Prager plastic flow model, combined with a Hencky strain-based hyperelasticity model, is used to compute soil stress. Water is modeled as a weakly compressible fluid. Analysis of the model demonstrates the efficacy of our approach for existing examples of overtopping dam breach, dam failures, and collisions. Simulation results from our model are compared with a physical-based breach model, WinDAM C. The new model can capture water and soil interaction at a finer granularity than WinDAM C. The new model gradually removes the granular material during the breach process. The impact of material properties on the dam breach process is also analyzed.

v-p material point method for weakly compressible problems

2018 ◽  
Vol 176 ◽  
pp. 170-181 ◽  
Author(s):  
Zhen-Peng Chen ◽  
Xiong Zhang ◽  
Kam Yim Sze ◽  
Lei Kan ◽  
Xin-Ming Qiu
Keyword(s):  
Material Point Method ◽  
Material Point ◽  
Point Method ◽  
Weakly Compressible
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