scholarly journals Dry granular masses impacting on rigid obstacles: numerical analysis and theoretical modelling

2021 ◽  
Author(s):  
Irene Redaelli ◽  
Claudio di Prisco ◽  
Francesco Calvetti
Keyword(s):  
Time Evolution ◽  
Impact Force ◽  
Theoretical Modelling ◽  
Existing Structures ◽  
Flow Length ◽  
Physically Based ◽  
Geometrical Factors ◽  
Force Time ◽  
Maximum Impact Force ◽  
The Impact

AbstractThe assessment of the time evolution of the impact force exerted by dry flowing masses on rigid obstacles is mandatory for the dynamic design of sheltering structures and the evaluation of the vulnerability of existing structures. In this paper, the results of an extensive numerical campaign performed by employing a discrete element method (DEM) code are presented and the role of different geometrical factors (flow length, height and front inclination) and state parameters (porosity and velocity) on the impact force–time evolution is investigated. The impact process is studied to correlate local information with the macroscopic response and a physically based force–time function, generalising the formula already introduced by the authors for the assessment of maximum impact force, in which each parameter is correlated with the previously mentioned factors, is proposed.

scholarly journals Experimental Study of the Debris Flow Slurry Impact and Distribution

2018 ◽  
Vol 2018 ◽  
pp. 1-15 ◽  
Author(s):  
Haixin Zhao ◽  
Lingkan Yao ◽  
Yong You ◽  
Baoliang Wang ◽  
Cong Zhang
Keyword(s):  
Debris Flow ◽  
Debris Flows ◽  
Impact Force ◽  
Influence Factors ◽  
Flume Experiment ◽  
Middle Point ◽  
Laboratory Flume ◽  
Critical Issues ◽  
Maximum Impact Force ◽  
The Impact

In this study, we present a new method to calculate debris flow slurry impact and its distribution, which are critical issues for designing countermeasures against debris flows. There is no unified formula at present, and we usually design preventive engineering according to the uniform distribution of the maximum impact force. For conducting a laboratory flume experiment, we arrange sensors at different positions on a dam and analyze the differences on debris flow slurry impact against various densities, channel slopes, and dam front angles. Results show that the force of debris flow on the dam distributes unevenly, and that the impact force is large in the middle and decreases gradually to the both sides. We systematically analyze the influence factors for the calculation of the maximum impact force in the middle point and give the quantitative law of decay from the middle to the sides. We propose a method to calculate the distribution of the debris flow impact force on the whole section and provide a case to illustrate this method.

DYNAMIC CHARACTERISTICS MEASUREMENTS OF A FORCE TRANSDUCER AGAINST SMALL AND SHORT-DURATION IMPACT FORCES

2014 ◽  
Vol 21 (1) ◽  
pp. 59-66 ◽  
Author(s):  
Mitra Djamal ◽  
Kazuhide Watanabe ◽  
Kyohei Irisa ◽  
Irfa Aji Prayogi ◽  
Akihiro Takita ◽  
...  
Keyword(s):  
Short Duration ◽  
Dynamic Characteristics ◽  
Impact Force ◽  
Inertial Force ◽  
Small Mass ◽  
Force Transducer ◽  
Force Transducers ◽  
Impact Forces ◽  
Maximum Impact Force ◽  
The Impact

Abstract A method for evaluating the dynamic characteristics of force transducers against small and short-duration impact forces is developed. In this method, a small mass collides with a force transducer and the impact force is measured with high accuracy as the inertial force of the mass. A pneumatic linear bearing is used to achieve linear motion with sufficiently small friction acting on the mass, which is the moving part of the bearing. Small and short-duration impact forces with a maximum impact force of approximately 5 N and minimum half-value width of approximately 1 ms are applied to a force transducer and the impulse responses are evaluated.

Numerical Simulation Analysis of Collision between Ship and Steel Sheet Pile Quay-Wall

2015 ◽  
Vol 744-746 ◽  
pp. 1175-1179 ◽  
Author(s):  
Peng Liu ◽  
Hong Wang ◽  
Chao Zhu
Keyword(s):  
Numerical Simulation ◽  
Steel Sheet ◽  
Impact Force ◽  
Simulation Analysis ◽  
Sheet Pile ◽  
Time Curve ◽  
Finite Element Software ◽  
Quay Wall ◽  
Force Time ◽  
The Impact

The impact process of 50000t ship and steel sheet pile bulkhead is simulated by finite element software ANSYS/LS-DYNA. This article acquires the impact force-time curve, equivalent force-time curve of steel sheet pile and the pressure-time curve of breast wall. Comparing the impact force of numerical simulation with the result of ship-bridge collision specifications, and general rules and characteristics are obtained. At the same time, put forward some measures to prevent the damage of wharf structure under the ship of large velocity impact, which provide theoretical references during the design, maintenance, and transformation of similar wharf.

A Comparative Study on the Effect of Mechanical Compliance for a Safe Physical Human–Robot Interaction

2020 ◽  
Vol 142 (6) ◽  
Author(s):  
Yu She ◽  
Siyang Song ◽  
Hai-Jun Su ◽  
Junmin Wang
Keyword(s):  
Impact Force ◽  
Variable Stiffness ◽  
Human Robot Interaction ◽  
Design Parameters ◽  
Robot Dynamics ◽  
Robot Interaction ◽  
Promising Alternative ◽  
Mechanical Compliance ◽  
Maximum Impact Force ◽  
The Impact

Abstract In this paper, we study the effects of mechanical compliance on safety in physical human–robot interaction (pHRI). More specifically, we compare the effect of joint compliance and link compliance on the impact force assuming a contact occurred between a robot and a human head. We first establish pHRI system models that are composed of robot dynamics, an impact contact model, and head dynamics. These models are validated by Simscape simulation. By comparing impact results with a robotic arm made of a compliant link (CL) and compliant joint (CJ), we conclude that the CL design produces a smaller maximum impact force given the same lateral stiffness as well as other physical and geometric parameters. Furthermore, we compare the variable stiffness joint (VSJ) with the variable stiffness link (VSL) for various actuation parameters and design parameters. While decreasing stiffness of CJs cannot effectively reduce the maximum impact force, CL design is more effective in reducing impact force by varying the link stiffness. We conclude that the CL design potentially outperforms the CJ design in addressing safety in pHRI and can be used as a promising alternative solution to address the safety constraints in pHRI.

Size Effects in the Impact of Carbon Fiber Reinforced Composite Structures

2018 ◽  
Vol 789 ◽  
pp. 155-160
Author(s):  
Yi Ou Shen ◽  
Yan Li
Keyword(s):  
Size Effects ◽  
Composite Structures ◽  
Impact Force ◽  
Flexural Rigidity ◽  
Experimental Results ◽  
Target Size ◽  
Mass Model ◽  
Energy Impact ◽  
Maximum Impact Force ◽  
The Impact

In this study, target size effects in the low energy impact response of plain CFRP plateswere investigated. It was found that increase the target size leads to a reduction in the maximumimpact force recorded during the test. This is due to the reduction on flexural rigidity of the largerpanels. The experimental results indicated that at energies above the first failure threshold, themaximum impact force does not coincidence with the predicting value. Two mathematical modelswere used to predict the maximum impact force including single degree of freedom (SDOF)spring-mass model and Energy-Balance (E-B) model. The predicting results were then comparedwith the experimental results, and both of the two models show good agreement with theexperimental results in elastic deformation region. In addition, the level of agreement between thepredictions and the experimental results indicate that both models are capable of modelling theimpact response of these CFRP panels at elastic regime.

EFFECT OF THE FLUID ON THE IMPACT FORCE OF THE WET MISSILE

2015 ◽  
Vol 2 (1) ◽  
Author(s):  
Duc-Kien Thai ◽  
Seung-Eock Kim
Keyword(s):  
Impact Force ◽  
Force Plate ◽  
Time History ◽  
Research Centre ◽  
Element Analysis ◽  
Time Histories ◽  
Target Wall ◽  
Force Time ◽  
Missile Test ◽  
The Impact

In this paper, the force-time histories of soft missiles, with and without filled water, impacting the target wall were investigated using finite element analysis. The force plate tests, with a dry missile (test FP8) and a wet missile (test FP16) carried out by Technical Research Centre of Finland (VTT), were used. The numerical analysis results were verified by comparing with those of experiments. A parametric analysis with different missile velocities was also performed to investigate the force-time history and impulse of the missile impact on target plate. Based on a comparison with the Riera approach, the coefficients were proposed to modify the Riera function. The analysis results show that, the Riera function accurately predicted the impact force time history in the case of the dry missile. However, in the case of the wet missile, the coefficients α from 1.24 to 1.45 are recommended to be added to the second term of the Riera function in the case in which the impact velocity is in the range of 70 m/s to 200 m/s.

Impact Response Spectrum for Design of Ship-Bridge Collisions

2014 ◽  
Vol 587-589 ◽  
pp. 1547-1553 ◽  
Author(s):  
Jun Jie Wang ◽  
Zhi Ran Yu
Keyword(s):  
Impact Force ◽  
Response Spectrum ◽  
Degree Of Freedom ◽  
Impact Response ◽  
Amplification Effect ◽  
Spectrum Method ◽  
Time Histories ◽  
Dynamic Amplification ◽  
Force Time ◽  
The Impact

Due to the complexity involved and limited study on the topic, the equivalent static method, adopted in the current codes for structural design of bridges under ship collisions, does not take into account the dynamic amplification effect correctly. An accurate assessment of impact force based on refined numerical simulation is time consuming and is normally too complex for ordinary design procedure. Herein, with reference to the earthquake response spectrum method, an impact response spectrum method, which considers the dynamic amplification effect and is efficient for design, is proposed. Through refined numerical simulations of ship-rigid wall collisions, 81 impact force time histories associated with 9 typical ships under 9 velocities are obtained. The dynamic magnification factor (DMF) of single-degree-of-freedom (SDOF) systems with different periods and damping ratios experiencing the 81 impact force time histories are then studied. The relationship of DMF and period under different damping ratios, i.e. the DMF spectrum, is yielded by statistical analysis, based on which the impact response spectrum is obtained. Finally, the design combination method for multi-degree-of-freedom based on the impact response spectrum of SDOF is discussed for a continuous beam bridge.

ANALYTICAL SOLUTION OF WEDGE WATER ENTRY BY USING SCHWARTZ–CHRISTOFFEL CONFORMAL MAPPING

2011 ◽  
Vol 02 (03) ◽  
pp. 337-354 ◽  
Author(s):  
PARVIZ GHADIMI ◽  
AMIR SAADATKHAH ◽  
ABBAS DASHTIMANESH
Keyword(s):  
Conformal Mapping ◽  
Impact Force ◽  
Offshore Structures ◽  
Water Entry ◽  
The Body ◽  
Water Impact ◽  
Local Pressure ◽  
Maximum Impact Force ◽  
The Impact ◽  
First Time

Water impact is one of the most critical phenomena from the viewpoint of the structural design of ships and offshore structures. The impact force can impose a large load with high local pressure on the body surface. On the other hand, determination of the maximum impact force during impact and acting point itself is very important in the design of floats. In this paper, the water entry of a two-dimensional wedge section is considered. This study is carried out in the framework of a potential-flow assumption. In particular, water impact on a dropping wedge with a constant velocity is pursued analytically by using the Schwartz–Christoffel conformal mapping. In order to determine a position of the wedge where the instantaneous effective force is largest during the impact, a particular equation is introduced here for the first time. The pressure distribution and maximum impact force are also calculated. The obtained results are compared against other numerical and experimental works and favorable agreement is displayed.

scholarly journals EXPERIMENT ON IMPACT DAMAGE OF CASTOR CAPSULE AND ITS INFLUENCING FACTORS OPTIMIZATION

2020 ◽  
Vol 61 (2) ◽  
pp. 87-96 ◽  
Author(s):  
Junming Hou ◽  
Yong Yang ◽  
Hongjie Zhu ◽  
Weixue Hu
Keyword(s):  
Water Content ◽  
Impact Force ◽  
Impact Damage ◽  
Impact Angle ◽  
Maximum Deformation ◽  
Combination Optimization ◽  
Damage Degree ◽  
Castor Seeds ◽  
Maximum Impact Force ◽  
The Impact

Castor is an important oil crop. Impact damage is critical in the process of castor capsule shelling, directly affecting the shelling effect of castor seeds. An experiment was taken to investigate it. To study the damage degree of castor capsule under the impact, water content, impact height, and impact angle were taken as test factors, and the maximum impact force and normal deformation were taken as test indexes. The combination optimization was carried out through the multi-objective genetic algorithm. The results show that the impact height has a significant effect on the maximum deformation (p<=0.01), and the water content and impact angle have a significant impact on the impact force (p<=0.05). The height and angle have a significant impact on the deformation (p<=0.01), and the water content has a significant impact on the deformation (p<=0.05).

Effect of Flexibility in Transverse Impact Problems

1997 ◽  
Author(s):  
Ahmet S. Yigit ◽  
Andreas P. Christoforou
Keyword(s):  
Multibody Systems ◽  
Computational Models ◽  
Functional Relationship ◽  
Impact Force ◽  
Impact Response ◽  
Flexible Body ◽  
Transverse Impact ◽  
Impact Problems ◽  
Maximum Impact Force ◽  
The Impact

Abstract The nature of impact response of a flexible body is studied. The key parameters which govern the nature of impact response are identified. The effects of these parameters on the impact response are examined through numerical simulations. It is shown that the normalized impact force and the type of impact response can be predicted through the functional relationship between the normalized maximum impact force and two nondimensional parameters termed as “loss factor” and “relative stiffness”. It is expected that the results of this study will be of great value in choosing adequate impact and computational models for the dynamic analysis of multibody systems subject to transverse impacts.

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