Influence of solid-fluid interaction on impact dynamics against rigid barrier: CFD-DEM modelling

Géotechnique ◽  
2021 ◽  
pp. 1-62
Author(s):  
Jun Fang ◽  
Lizhong Wang ◽  
Yi Hong ◽  
Jidong Zhao
Keyword(s):  
Impact Dynamics ◽  
Rigid Barrier ◽  
Fluid Interaction

Impact Dynamics of Boulder-Enriched Debris Flow on a Rigid Barrier

2021 ◽  
Vol 147 (3) ◽  
pp. 04021004
Author(s):  
Charles W. W. Ng ◽  
Haiming Liu ◽  
Clarence E. Choi ◽  
Julian S. H. Kwan ◽  
W. K. Pun
Keyword(s):  
Debris Flow ◽  
Impact Dynamics ◽  
Rigid Barrier

scholarly journals Influence of debris flow solid fraction on rigid barrier impact

2017 ◽  
Vol 54 (10) ◽  
pp. 1421-1434 ◽  
Author(s):  
D. Song ◽  
C.W.W. Ng ◽  
C.E. Choi ◽  
G.G.D. Zhou ◽  
J.S.H. Kwan ◽  
...  
Keyword(s):  
Debris Flow ◽  
Solid Fraction ◽  
Impact Pressure ◽  
Frontal Impact ◽  
Rigid Barrier ◽  
Pile Up ◽  
Run Up ◽  
The Impact ◽  
Fluid Interaction ◽  
Fluid Phases

The dynamics of debris flows are fundamentally governed by the interaction between the solid and fluid phases. However, current approaches used to estimate impact load treat debris flow as an equivalent fluid without considering solid–fluid interaction separately from other factors. In this study, a series of centrifuge tests was carried out to investigate the influence of interaction between solid and fluid phases on single-surge debris flow impact on a rigid barrier. The effect of solid–fluid interaction was studied by varying the solid fraction of the flows. A model rigid barrier was instrumented to capture induced bending moment and impact pressure. Test results demonstrate that the transition from a pile-up mechanism to a run-up mechanism is governed by the solid fraction and thus the grain contact stresses. The rigid barrier design for the impact with a pile-up mechanism is mainly dominated by the static load. Contrary to the hydrodynamic approach, which assumes that the frontal impact is the most critical, the frontal impact of a run-up mechanism contributes less than 25% of the total force impulse. The consideration of static loading leads to the development of a new impact model with a triangular distribution of the impact pressure.

Determination of Transport Packaging Kit Speed before Impact with a Rigid Barrier during Emergency Impact Tests on the Missile Track

2020 ◽  
Vol 34 (1) ◽  
pp. 26-37
Author(s):  
S.I. Gerasimov ◽  
V.I. Erofeev ◽  
V.A. Kikeev ◽  
O.V. Krivosheev ◽  
V.I. Kostin ◽  
...  
Keyword(s):  
Rigid Barrier ◽  
Impact Tests

scholarly journals A Rational Numerical Method for Simulation of Drop-Impact Dynamics of Oleo-Pneumatic Landing Gear

2021 ◽  
Vol 11 (9) ◽  
pp. 4136
Author(s):  
Rosario Pecora
Keyword(s):  
Numerical Method ◽  
Initial Conditions ◽  
Impact Load ◽  
Numerical Models ◽  
Landing Gear ◽  
Design Stage ◽  
Impact Dynamics ◽  
State Variables ◽  
Adopted Model ◽  
The Impact

Oleo-pneumatic landing gear is a complex mechanical system conceived to efficiently absorb and dissipate an aircraft’s kinetic energy at touchdown, thus reducing the impact load and acceleration transmitted to the airframe. Due to its significant influence on ground loads, this system is generally designed in parallel with the main structural components of the aircraft, such as the fuselage and wings. Robust numerical models for simulating landing gear impact dynamics are essential from the preliminary design stage in order to properly assess aircraft configuration and structural arrangements. Finite element (FE) analysis is a viable solution for supporting the design. However, regarding the oleo-pneumatic struts, FE-based simulation may become unpractical, since detailed models are required to obtain reliable results. Moreover, FE models could not be very versatile for accommodating the many design updates that usually occur at the beginning of the landing gear project or during the layout optimization process. In this work, a numerical method for simulating oleo-pneumatic landing gear drop dynamics is presented. To effectively support both the preliminary and advanced design of landing gear units, the proposed simulation approach rationally balances the level of sophistication of the adopted model with the need for accurate results. Although based on a formulation assuming only four state variables for the description of landing gear dynamics, the approach successfully accounts for all the relevant forces that arise during the drop and their influence on landing gear motion. A set of intercommunicating routines was implemented in MATLAB® environment to integrate the dynamic impact equations, starting from user-defined initial conditions and general parameters related to the geometric and structural configuration of the landing gear. The tool was then used to simulate a drop test of a reference landing gear, and the obtained results were successfully validated against available experimental data.

scholarly journals How grow-and-switch gravitropism generates root coiling and root waving growth responses in Medicago truncatula

2015 ◽  
Vol 112 (42) ◽  
pp. 12938-12943 ◽  
Author(s):  
Tzer Han Tan ◽  
Jesse L. Silverberg ◽  
Daniela S. Floss ◽  
Maria J. Harrison ◽  
Christopher L. Henley ◽  
...  
Keyword(s):  
Medicago Truncatula ◽  
Growth Medium ◽  
Plant Root ◽  
Experimental Studies ◽  
Optimal Strategies ◽  
Growth Responses ◽  
Inclined Plane ◽  
Rigid Barrier ◽  
Primary Roots ◽  
Root Waving

Experimental studies show that plant root morphologies can vary widely from straight gravity-aligned primary roots to fractal-like root architectures. However, the opaqueness of soil makes it difficult to observe how environmental factors modulate these patterns. Here, we combine a transparent hydrogel growth medium with a custom built 3D laser scanner to directly image the morphology of Medicago truncatula primary roots. In our experiments, root growth is obstructed by an inclined plane in the growth medium. As the tilt of this rigid barrier is varied, we find Medicago transitions between randomly directed root coiling, sinusoidal root waving, and normal gravity-aligned morphologies. Although these root phenotypes appear morphologically distinct, our analysis demonstrates the divisions are less well defined, and instead, can be viewed as a 2D biased random walk that seeks the path of steepest decent along the inclined plane. Features of this growth response are remarkably similar to the widely known run-and-tumble chemotactic behavior of Escherichia coli bacteria, where biased random walks are used as optimal strategies for nutrient uptake.

Crystal–fluid interaction: the evolution of stilbite structure at high pressure

2021 ◽  
Vol 48 (1) ◽  
Author(s):  
Yu. V. Seryotkin ◽  
S. N. Dementiev ◽  
A. Yu. Likhacheva
Keyword(s):  
High Pressure ◽  
Fluid Interaction
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