Towards an understanding of the chemo-mechanical influences on kidney stone failure via the material point method

This paper explores the use of the meshfree computational mechanics method, the Material Point Method (MPM), to model the composition and damage of typical renal calculi, or kidney stones. Kidney stones are difficult entities to model due to their complex structure and failure behavior. Better understanding of how these stones behave when they are broken apart is a vital piece of knowledge to medical professionals whose aim is to remove these stone by breaking them within a patient’s body. While the properties of individual stones are varied, the common elements and proportions are used to generate synthetic stones that are then placed in a digital experiment to observe their failure patterns. First a more traditional engineering model of a Brazil test is used to create a tensile fracture within the center of these stones to observe the effect of stone consistency on failure behavior. Next a novel application of MPM is applied which relies on an ultrasonic wave being carried by surrounding fluid to model the ultrasonic treatment of stones commonly used by medical practitioners. This numerical modeling of Extracorporeal Shock Wave Lithotripsy (ESWL) reveals how these different stones failure in a more real-world situation and could be used to guide further research in this field for safer and more effective treatments.

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The material point method for simulating dense snow avalanches over complex real terrain

10.5194/egusphere-egu21-6045 ◽

2021 ◽

Author(s):

Xingyue Li ◽

Betty Sovilla ◽

Chenfanfu Jiang ◽

Johan Gaume

Keyword(s):

Material Point Method ◽

Granular Flows ◽

Material Point ◽

Full Scale ◽

Point Method ◽

Constitutive Law ◽

Snow Avalanches ◽

Failure Patterns ◽

Snow Properties ◽

Modified Cam Clay

<p>Various dynamics models can reproduce the motion of avalanches from release to deposition. These models often simulate a conceptual avalanche, adopt depth-averaged approaches and do not resolve variations along flow depth direction, and thus have clear limitations. This study presents three-dimensional, full-scale modeling of dense snow avalanches performed using the complex real terrain of the Vall&#233;e de la Sionne avalanche test site in Switzerland. We use the material point method (MPM) and a large-strain elastoplastic constitutive law for snow based on a Modified Cam Clay model. In our simulations, various and transient avalanche flow regimes are simulated by setting distinct snow properties. Snow avalanches are investigated from release to deposition. Detailed simulation results include the initial failure patterns, the mechanical behavior during the flow, and the characteristics of the final avalanche deposits. More specifically in the release zone, we can observe brittle and ductile fractures depending on the defined snow properties. During the flow phase, we monitor the temporal and spatial variations of snow density in the avalanche. In particular, cohesionless granular flows, cohesive granular flows, and plug flows are associated with snow fracture, compaction, and expansion. Finally, we can observe the structure of the avalanche deposit surfaces which show distinguishable differences in terms of smoothness, granulation, and compacting shear planes. This new model can offer a quantitative analysis for studying avalanches in different regimes and provide a powerful tool for exploring the dynamics of full-scale avalanches on complex real terrain, with high physical detail.</p>

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An Investigation of Rainfall-Induced Landslides From the Pre-Failure Stage to the Post-Failure Stage Using the Material Point Method

Frontiers in Earth Science ◽

10.3389/feart.2021.764393 ◽

2021 ◽

Vol 9 ◽

Author(s):

Wei-Lin Lee ◽

Mario Martinelli ◽

Chjeng-Lun Shieh

Keyword(s):

Numerical Model ◽

Pore Water ◽

Numerical Solutions ◽

Pore Water Pressure ◽

Water Pressure ◽

Material Point Method ◽

Material Point ◽

Point Method ◽

Failure Behavior ◽

Clear Understanding

The kinematic behavior of rainfall-induced landslides from the pre-failure stage to post-failure stage contains important information for risk assessment and management. Because a complex relationship exists between rainfall conditions, pore water pressure, soil strength, and movement rates, a numerical model is the most efficient way to investigate the behavior of rainfall-induced landslides. In this study, the material point method (MPM) is used to investigate the dynamic behavior of landslides. First, the rainfall boundary conditions are extensively verified by comparing 1-D consolidation tests against other numerical solutions. Then, a numerical model is used to simulate a lab-scale rainfall-induced slope failure. A parametric study shows the influence of rainfall intensity on pore water pressure development, failure triggering time, surface displacement, and velocity. The use of the MPM provides a clear understanding in the failure mechanism and post-failure behavior of a rainfall-induced landslide.

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A Hybrid Material Point Method for Frictional Contact with Diverse Materials

Proceedings of the ACM on Computer Graphics and Interactive Techniques ◽

10.1145/3340258 ◽

2019 ◽

Vol 2 (2) ◽

pp. 1-24 ◽

Cited By ~ 7

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

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

Tunnelling and Underground Space Technology ◽

10.1016/j.tust.2021.103904 ◽

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

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A moving least squares material point method with displacement discontinuity and two-way rigid body coupling

ACM Transactions on Graphics ◽

10.1145/3197517.3201293 ◽

2018 ◽

Vol 37 (4) ◽

pp. 1-14 ◽

Cited By ~ 31

Author(s):

Yuanming Hu ◽

Yu Fang ◽

Ziheng Ge ◽

Ziyin Qu ◽

Yixin Zhu ◽

...

Keyword(s):

Rigid Body ◽

Least Squares ◽

Material Point Method ◽

Material Point ◽

Point Method ◽

Displacement Discontinuity ◽

Moving Least Squares

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Dam Breach Simulation with the Material Point Method

Computation ◽

10.3390/computation9020008 ◽

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.

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