scholarly journals Numerical Investigation of Multiple-Impact Behavior of Granular Flow on a Rigid Barrier

Water ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 3228
Author(s):  
Bei Zhang ◽  
Yu Huang ◽  
Ping Lu ◽  
Chunxiang Li
Keyword(s):  
Impact Force ◽  
Dead Zone ◽  
Particle Interaction ◽  
Impact Behavior ◽  
Particle Collision ◽  
Rigid Barrier ◽  
Impact Mechanism ◽  
The Dead ◽  
Multiple Impact ◽  
The Impact

The debris–barrier interaction issue has gained considerable attention among the engineering community, but most researches have only focused on the single-surge impact condition, with the multiple-surge impact mechanism still lacking clarity. However, multiple-surge impact is more typical in the field. Thus, we conduct some numerical simulations based on the discrete element method (DEM) and present a series of results that provide preliminary insights into the multiple-surge impact mechanism. The DEM model is firstly calibrated using physical experimental results and then used to investigate the flow kinematics, impact dynamics and energy evolution of the successive impact process. The results indicate that compared with single-surge conditions, the barrier is safer under multiple-surge impact as the deposition spreading distance is extended by 6–20% and the impact force is reduced by 6–30%. The dead zone formed by the previous surge behaves as a cushioning layer and a medium for momentum transfer. Three mechanisms of energy dissipation during surge–dead-zone interactions were identified: friction and penetration at the interaction face between the surge and dead zone, inelastic deformation of the dead zone, and inter-particle interaction within the surge. Each component was analyzed, which shows that inter-particle collision friction accounts for over 60% of the total energy loss during surge–dead-zone interaction. In addition, the performance of granular jump theory in predicting the multiple-surge impact force is assessed, and some possible modifications are proposed. Finally, some engineering implications from the presented numerical results are discussed.

scholarly journals Effects of dynamic fragmentation on the impact force exerted on rigid barrier: centrifuge modelling

2019 ◽  
Vol 56 (9) ◽  
pp. 1215-1224 ◽  
Author(s):  
C.W.W. Ng ◽  
C.E. Choi ◽  
D.K.H. Cheung ◽  
Y. Cui
Keyword(s):  
Volume Fraction ◽  
Impact Force ◽  
Inertial Particles ◽  
Size Segregation ◽  
Centrifuge Modelling ◽  
Rigid Barrier ◽  
Flow Energy ◽  
Dynamic Fragmentation ◽  
Large Particles ◽  
The Impact

Bi-dispersity is a prerequisite for grain-size segregation, which transports the largest particles to the flow front. These large and inertial particles can fragment upon impacting a barrier. The amount of fragmentation during impact strongly influences the force exerted on a rigid barrier. Centrifuge modelling was adopted to replicate the stresses for studying the effects of bi-dispersity in a granular assembly and dynamic fragmentation on the impact force exerted on a model rigid barrier. To study the effects of bi-dispersity, the ratio between the diameters of small and large particles (δs/δl), characterizing the particle-size distribution (PSD), was varied as 0.08, 0.26, and 0.56. The volume fraction of the large particles was kept constant. A δs/δl tending towards unity characterizes inertial flow that exerts sharp impulses, and a diminishing δs/δl characterizes the progressive attenuation of these sharp impulses by the small particles. Flows dominated by grain-contact stresses (δs/δl < 0.26), as characterized by the Savage number, are effective at attenuating dispersive stresses of the large particles, which are responsible for reducing dynamic fragmentation. By contrast, flows dominated by grain-inertial stresses (δs/δl > 0.26) exhibit up to 66% more impulses and 4.3 times more fragmentation. Dynamic fragmentation of bi-disperse flows impacting a rigid barrier can dissipate about 30% of the total flow energy.

Energy Parameters of the Binder during Activation in the Vortex Layer Apparatus

2019 ◽  
Vol 945 ◽  
pp. 98-103 ◽  
Author(s):  
Ruslan A. Ibragimov ◽  
Evgeniy V. Korolev ◽  
T.R. Deberdeev ◽  
V.V. Leksin ◽  
Denis B. Solovev
Keyword(s):  
Material Science ◽  
Fill Factor ◽  
Impact Force ◽  
Ferromagnetic Particle ◽  
Particle Collision ◽  
Test Device ◽  
Vortex Layer ◽  
The Impact ◽  
Ground Material ◽  
Grinding Time

Improving the efficiency of construction composites is a relevant problem for modern-day material science. One of the ways to solve the problem consists in activating the binders by means of vortex-layer devices. Mathematical transformations produced a formula for calculating the dependency of the number of ferromagnetic-particle collision on the number and velocity of such particles, as well as on the device chamber fill factor. The results obtained by applying the proposed formula differ from D.D. Logvinenko's model by 10% at max. We calculated the impact force, the impulse of the grinding body in the vortex-layer device, as well as the amount of applied energy per unit of mass of the ground material. It was found out that the impact force and the impulse of force were maximized in the test device. At the same time, energy applied over the grinding time necessary to even out the binder dispersion in the vortex-layer device was 2 to 4.8 times greater compared to conventional devices.

The Determination of Stagnant Rate of Servo System Based on Adaptive Chatter Algorithm

2013 ◽  
Vol 860-863 ◽  
pp. 1787-1790
Author(s):  
Ting Zhao ◽  
Xiao Zhi Qiu ◽  
Ding Cai ◽  
Bao Hua Huang
Keyword(s):  
Dead Zone ◽  
Servo System ◽  
Signal Frequency ◽  
Determination Method ◽  
Dynamic Effects ◽  
Change Rate ◽  
The Dead ◽  
The Impact ◽  
Selection Of

The current determination of stagnant rate cannot eliminate the dynamic effects, especially the change rate of speed. Consider the problem of the current determination of stagnant rate, this work presents one determination method based on adaptive chatter algorithm .Simulation shows it can eliminate the impact of dynamics effectively. The method achieves the measurement online due to the signal of chatter can adapt to the dead zone of servo system. At last, the selection of the signal frequency is discussed.

Energy-Shunting Hip Padding System Attenuates Femoral Impact Force in a Simulated Fall

1995 ◽  
Vol 117 (4) ◽  
pp. 409-413 ◽  
Author(s):  
S. N. Robinovitch ◽  
W. C. Hayes ◽  
T. A. McMahon
Keyword(s):  
Soft Tissue ◽  
Soft Tissues ◽  
Impact Force ◽  
The Elderly ◽  
Impact Behavior ◽  
Human Female ◽  
Female Pelvis ◽  
The Mean ◽  
The Impact

Recent studies suggest that hip padding systems reduce the incidence of hip fractures during falls. However, no data exist on the force attenuating capacity of hip pads under realistic fall impact conditions, and thus it is difficult to compare the protective merit of various pad designs. Our goal is to design a comfortable hip padding system which reduces femoral impact force in a fall below the mean force required to fracture the elderly cadaveric femur. In pursuit of this objective, we designed and constructed a hip pad testing system consisting of an impact pendulum and surrogate human pelvis. We then developed a hip pad containing a shear-thickening material which allows for shunting of the impact energy away from the femur and into the surrounding soft tissue. Finally, we conducted experiments to assess whether the surrogate pelvis accurately represents the impact behavior of the human female pelvis in a fall, and to determine whether our energy-shunting pad attenuates femoral impact force in a fall more effectively than seven available padding systems. We found the surrogate pelvis accurately represented the human female pelvis in regional variation in soft tissue stiffness, total effective stiffness and damping, and impact force attenuation provided by trochanteric soft tissues. We also found that our padding system attenuated femoral impact force by 65 percent, thereby providing two times the force attenuation of the next best system. Moreover, the energy-shunting pad was the only system capable of lowering femoral impact force well below the mean force required to fracture the elderly femur in a fall loading configuration. These results suggest that the force attenuating potential of hip pads which focus on shunting energy away from the femur is superior to those which rely on absorbing energy in the pad material. While these in-vitro results are encouraging, carefully designed prospective clinical trials will be necessary to determine the efficacy of these approaches to hip fracture prevention.

scholarly journals Dynamic Response Analysis of Retaining Dam under the Impact of Solid-Liquid Two-Phase Debris Flow Based on the Coupled SPH-DEM-FEM Method

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Bailong Li ◽  
Changming Wang ◽  
Yanying Li ◽  
Yiao Liu ◽  
Nan Jiang ◽  
...  
Keyword(s):  
Dynamic Response ◽  
Debris Flow ◽  
Impact Force ◽  
Time History ◽  
Impact Behavior ◽  
Response Analysis ◽  
Two Phase ◽  
Fem Method ◽  
Solid Liquid ◽  
The Impact

Based on the coupled SPH-DEM-FEM numerical method, this paper analyzes the dynamic interaction of solid debris flow particle-liquid debris flow slurry-retaining dam in order to explore the dynamic response of retaining dam under the impact of the solid-liquid two-phase debris flow and delves into the process of the debris flow impact on the dam, the impact force of debris flow, and the elastic-plastic time-history characteristics of the dam under different slopes of trapezoidal grooves. The calculation results show that the coupled SPH-DEM-FEM method can vividly simulate the impact behavior of the solid-liquid two-phase debris flow on the dam, reproduce the impact, climbing, and siltation in the process of the debris flow impact; the dynamic time-history curve of the retaining dam is consistent with the law of the literature, and the result of the debris flow impact force obtained is close to that of the empirical formula. Moreover, this paper studies the impact force distribution of the debris flow impact process. The results have a certain reference value for the study of the dynamic response of the retaining dam under the impact of the solid-liquid two-phase debris flow and the engineering design of the debris flow-retaining dam.

scholarly journals Experimental Investigation on the Impact Dynamics of Saturated Granular Flows on Rigid Barriers

2021 ◽  
Vol 27 (1) ◽  
pp. 127-138
Author(s):  
Nicoletta Sanvitale ◽  
Elisabeth Bowman ◽  
Miguel Angel Cabrera
Keyword(s):  
Particle Size ◽  
High Speed ◽  
Impact Load ◽  
Granular Flows ◽  
Normal Pressure ◽  
Impact Behavior ◽  
Small Scale ◽  
Rigid Barrier ◽  
Fluid Saturation ◽  
The Impact

ABSTRACT Debris flows involve the high-speed downslope motion of rocks, soil, and water. Their high flow velocity and high potential for impact loading make them one of the most hazardous types of gravitational mass flows. This study focused on the roles of particle size grading and degree of fluid saturation on impact behavior of fluid-saturated granular flows on a model rigid barrier in a small-scale flume. The use of a transparent debris-flow model and plane laser-induced fluorescence allowed the motion of particles and fluid within the medium to be examined and tracked using image processing. In this study, experiments were conducted on flows consisting of two uniform and one well-graded particle size gradings at three different fluid contents. The evolution of the velocity profiles, impact load, bed normal pressure, and fluid pore pressure for the different flows were measured and analyzed in order to gain a quantitative comparison of their behavior before, during, and after impact.

scholarly journals Finite Element Simulation of the Vibration Provided by Sandwich Rigid Panel with a Resilient Material In Between under Heavyweight Impact

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Shun-Fa Hwang ◽  
Chao-Wen Chen ◽  
Sung-Chin Chung ◽  
Yaw-Shyan Tsay
Keyword(s):  
Finite Element ◽  
Impact Force ◽  
Impact Behavior ◽  
Sound Insulation ◽  
Explicit Finite Element ◽  
Element Simulation ◽  
Rubber Model ◽  
Two Parameters ◽  
The Impact ◽  
Impact Vibration

The purpose of the present work is to use an explicit finite element code to model the impact behavior of a heavyweight impact source like rubber ball and to predict the floor impact vibration of resilient materials, which are used in the floor coverings construction for sound insulation. To simulate the impact force of rubber balls, the hyperviscoelastic rubber model is applied. Then, this rubber model is used in the simulation for the impact vibration of resilient materials. The results indicate that the hyperviscoelastic rubber model could precisely simulate the impact force of rubber balls, as its two parameters are properly chosen according to the desired impact force. Also, the present model could capture the impact and vibration behavior of the considered materials and reasonably evaluate the insulation effect of resilient materials.

Interaction between dry granular flow and rigid barrier with basal clearance: analytical and physical modelling

2020 ◽  
Vol 57 (2) ◽  
pp. 236-245 ◽  
Author(s):  
Clarence Edward Choi ◽  
Charles Wang Wai Ng ◽  
Haiming Liu ◽  
Yu Wang
Keyword(s):  
Granular Flow ◽  
Impact Force ◽  
Particle Diameter ◽  
Physical Modelling ◽  
Impact Model ◽  
Jump Height ◽  
Rigid Barrier ◽  
Physical Experiments ◽  
Dry Granular Flow ◽  
The Impact

Some types of barriers are designed with a clearance between the bottom of the barrier and the channel bed. This feature allows small discharges to pass, thereby reducing the maintenance required over the service life of the barrier. Aside from the practical function of a clearance, it influences the impact force, jump height, and discharge. In this paper, a series of physical experiments was conducted using a 6 m long flume to model the interaction between dry granular flow and rigid barrier with a basal clearance. The ratio between the clearance and particle diameter Hc/D was varied from 0 to 10. The channel inclination was varied from 15° to 35° to achieve different Froude numbers before impact. A new impact model for predicting impact force exerted on the barrier with a basal clearance is presented and evaluated. Results reveal that Hc ≥ 3D is capable of reducing the impact force and overflow. Findings from this study highlight the importance of considering the effects of basal clearance on the design of multiple-barrier systems.

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