A study on the frontal oblique collision-induced derailment mechanism in subway vehicles

Author(s):  
Shuguang Yao ◽  
Huifen Zhu ◽  
Mingyang Liu ◽  
Zhixiang Li ◽  
Ping Xu ◽  
...  

Oblique collisions can more easily lead to train derailment and cause heavy casualties. In this paper, a fine finite-element model of a subway head vehicle–rigid wall frontal oblique collision was established and validated by a single wheelset derailment simulation. Furthermore, the derailment mechanisms and patterns under an oblique impact angle of 6.34°–40° and at an impact speed of 8–40 km/h were studied via simulation. The results indicated that three types of derailment, such as roll-over derailment, climb/roll-over derailment and wheel-lift derailment, have occurred. When the impact speed was set to 25 km/h, a climb/roll-over derailment occurred under the impact angle of greater than 40°; a roll-over derailment occurred under the impact angle of 20°–40°; and the vehicle would not derail when the impact angle was less than 15°. When the impact angle was 6.34°, the vehicle was in danger of wheel-lift derailment with the largest wheel vertical displacement of 26.83 mm and lateral displacement of 12.52 mm under the impact speed of 40 km/h, but it was safe with the largest displacement of no more than 18 mm and lateral displacement of 8.39 mm if the impact speed was less than 40 km/h. It is shown that the derailment patterns are more sensitive to the impact angle. Therefore, both the lateral and vertical displacements should be considered when studying the oblique collision-induced derailment mechanisms and patterns.

Author(s):  
Akemi Nishida ◽  
Minoru Nagai ◽  
Haruji Tsubota ◽  
Yinsheng Li

Many empirical formulas have been proposed for evaluating local damage to reinforced concrete (RC) structures caused by impacts of rigid missiles. Most of these formulas have been derived based on impact tests normal to the target structures. Up to now, few impact tests oblique to the target structures have been carried out. This study has been conducted with the purpose of proposing a new formula for evaluating the local damage caused by oblique impacts based on previous experimental and simulation results. In this paper, the results of simulation analyses for evaluating the local damage to a RC panel subjected to normal and oblique impacts by rigid and soft missiles, by using the simulation method that was validated using the results of previous impact experiments. Based on the results of these simulation analyses, the effects of the rigidity of the missile as well as the impact angle on the local damage to the target structures are clarified.


2018 ◽  
Author(s):  
Nick H. Duong ◽  
J. Ma ◽  
Shuting Lei

In this paper, the commercial FEM software package Abaqus is employed to model a novel nanomachining process, in which an atomic force microscope (AFM) is used as a platform and the nano abrasives injected in slurry between the workpiece and the vibrating AFM probe impact the workpiece and result in nanoscale material removal. Diamond particles are used as loose abrasives. The ductile material model is used to describe the behavior of the silicon workpiece. The effects of impact speed, impact angle, and the frictional coefficient between the workpiece and abrasives on material removal mechanism are investigated. It is found that the impact speed, impact angle, and frictional coefficient between the silicon workpiece and nanoabrasives have big influence on material removal volume in this novel nanomachining process.


2020 ◽  
Vol 15 (3) ◽  
pp. 443-449
Author(s):  
Zhang Shusheng ◽  
Lu Hao ◽  
Zhang Li-Zhi ◽  
Riffat Saffa ◽  
Ure Zafer ◽  
...  

Abstract In this paper, oblique impact of a single rain droplet on super-hydrophobic surface with randomly distributed rough structures was investigated by lattice Boltzmann method. The effects of the impact angle of the droplet as well as the skewness and kurtosis of rough surface on the bouncing ability of the droplet were in this paper. It was found that the oblique impact can effectively reduce the contact time in the process of droplet bouncing off, because the energy consumption caused by the pinning effect is reduced. Moreover, the contact time most possibly reaches the shortest when the impact angle is 45°. Decreasing the skewness and keeping the kurtosis around 4.0 can enhance the bouncing ability during the droplet oblique impact on randomly distributed rough surfaces. The results are useful for the design of building structures.


Author(s):  
T. I. Khabakhpasheva ◽  
A. A. Korobkin

The two-dimensional motion of a rigid body with a smooth surface is studied during its oblique impact on a liquid layer. The problem is coupled: the three degrees of freedom of the moving body are determined together with the liquid flow and the hydrodynamic pressure along the wetted part of the body surface. The impact process is divided into two temporal stages. During the first stage, the wetted region expands at a high speed with jetting flows at both ends of the wetted region. In the second stage, the free surface of the liquid is allowed to separate from the body surface. The position of the separation point is determined with the help of the Brillouin–Villat condition. Calculations are performed for elliptic cylinders of different masses and with different orientations and speeds before the impact. The horizontal and vertical displacements of the body, as well as its angle of rotation and corresponding speeds are investigated. The model developed remains valid until the body either touches the bottom of the liquid or rebounds from the liquid.


2022 ◽  
Vol 905 ◽  
pp. 67-72
Author(s):  
Shang Wang ◽  
Rui Can Hao ◽  
Hua Gang Liu ◽  
Xiao Chen Wang ◽  
Quan Yang

In order to improve the energy efficiency of shot blasting impact descaling, a three-dimensional finite element impact descaling model was established. Based on the finite element model, the cracking behavior of the scale layer on hot rolled strip from different impacts angles was simulated. The results of finite element calculation and theoretical analysis show that: (1)Under the premise of constant velocity, the descaling area increases with the increase of impact angle, but the increasing rate tends to be moderate. (2)The depth of the impact tunnel and the residual compressive stress surface (-200 MPa) increase as the impact angle goes bigger. The ideal range of impact angle for shot blasting descaling should be 60°-75°.


2011 ◽  
Vol 255-260 ◽  
pp. 3150-3155
Author(s):  
Ping Li ◽  
Chen He ◽  
Gui Xian Wu ◽  
Xiu Li Wang

Impacting and compacting technology is widely applied for re-built old PCC pavement. However, underground pipe would be influenced by impacting machine to possibly occur fracture. A 3D finite element model was established by ADINA software to analyze distribution of additional stress and displacement upon pipe when machine traveled across different positions of slab. The results indicated that longitudinal compressive stress and vertical displacements at the corner of the slab were larger than those at the longitudinal middle fringe of the slab; the influenced depth of additional stress caused by impacting force was about 2.5m and additional stress decayed quickly with the increasing depth; the maximum soil pressure measured in field was smaller than that in numerical simulation.


Author(s):  
Tom Allen ◽  
James Ibbitson ◽  
Steve Haake

Oblique impacts between a ball and surface are a key part of many sports. Previous work has shown that a ball can slide, over-spin or roll at the end of an impact, depending on impact conditions. Inbound spin ratio was analysed to determine if it could be used to identify what is likely to happen at the end of impact for all sports regardless of surface, ball type, impact velocity, angle and spin. A predictive model, in the form of a finite element model, of a tennis ball was validated against experimental data for oblique impacts with inbound spin ratios in the range of –1 to 1. Spin ratio is defined as the product of the ball’s angular velocity and radius divided by the centre of mass velocity tangential to the surface. The finite element model was then used to determine the effect of impact conditions and ball parameters on outbound spin ratio. The study showed that for constant inbound spin ratio, outbound spin ratio was dependent on inbound velocity and angle. For constant inbound velocity and angle, decreasing the mass and increasing the stiffness of the ball through a change in material properties resulted in an increase in the maximum outbound spin ratio. Inbound spin ratio can be used to predict how a ball will rebound from a surface; however, inbound velocity and angle must be constant. Spin ratio can therefore be used to compare the impact characteristics for different ball and surface scenarios.


2014 ◽  
Vol 2014 ◽  
pp. 1-8
Author(s):  
S. Shasthri ◽  
V. Kausalyah ◽  
Qasim H. Shah ◽  
Kassim A. Abdullah ◽  
Moumen M. Idres ◽  
...  

The effects of bullet vehicle crash impact angle, child restraint system design, and restraint harness slack at side impact speed of 32.2 km/h (20 mph) on moments sustained at the neck by a three-year-old child are investigated. Mathematical models are built using the response surface method based on simulation results whereby good fitness is achieved. The singular and cross interactive effect of each predictor on the neck moment are analyzed. The number of significant parameters affecting the neck moment is shown to be the largest for wide impact angles (ϕ≥60°) and the impact angle parameter is largely revealed to be the most sensitive. An ideal safe range for low neck moment has been established to be within ϕ angles 45° and 65°. It is further shown that the nature of all parameters effect on the neck moment is highly dependent on the impact angle range.


2012 ◽  
Vol 178-181 ◽  
pp. 1611-1614 ◽  
Author(s):  
Xian Min Zhang ◽  
Qian Dong

Considering the joint loading-transfer effect, a 3-D finite element model which consists of thirty full-scale slabs is established. Making the aircraft loads act on different positions and calculating their vertical displacements. The results indicate that the loading area is compressive and the regions far away from loading area are tensile and that the vertical displacement curves change dramatically when aircraft wheels act on different locations.


2011 ◽  
Vol 368-373 ◽  
pp. 599-603
Author(s):  
Wei Shi ◽  
Jin Han ◽  
Yong Bin Li

Geogrid-reinforced retaining wall is widely used in civil engineering, the role of geogrid reinforcement and the calculations of reinforcement material in the retaining wall design need further refinement.This paper analyzes the fly ash retaining wall with and without reinforcement by using finite element software of FLAC3D,studys the impact of geogrid-reinforced function on the stability of fly ash retaining wall ,gets the design parameters of geogrid-reinforced fly ash retaining wall.The numerical results show that: the fly ash retaining walls' safety factor is lower when its height is greater than 6m,reinforcement is needed for fly ash retaining wall to improve its safety factor to ensure the stability of retaining wall.Simulate and analyze the 8m high geogrid reinforced fly ash retaining wall,the results show that: increasing the reinforcement spacing can increase the lateral and vertical displacement of geogrid reinforced fly ash retaining wall, the maximum vertical displacement of retaining wall is in the upper wall,maximum lateral displacement occurs in the lower parts of the retaining wall;the reasonable distance of 8m high fly ash retaining wall is 0.8m.


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