3D Dynamic Hydroelasticity Analysis of Light Weight Pyramidal Sandwich Plates with Imperfection Subjected to Water Impact

2013 ◽  
Vol 390 ◽  
pp. 266-272
Author(s):  
Hao Wang ◽  
Yuan Sheng Cheng ◽  
Jun Liu
Keyword(s):  
Numerical Results ◽  
Impact Pressure ◽  
Analytical Prediction ◽  
Light Weight ◽  
Water Impact ◽  
Estimation Model ◽  
Plate Structures ◽  
Maximum Deformation ◽  
The Impact ◽  
Fluid Solid Interaction

The aim of this work is to investigate the hydroelastic responses of rectangular, clamped light weight pyramidal sandwich plate structures with imperfection (LWPSPS-IM) subjected to water impact via analytical prediction and numerical simulation. Firstly, the characteristics of impact pressure and structure deformation are computed by using FEM program LS-DYNA based on the proposed 3D multi-physics computational model. Numerical results show that the impact pressure of total fluid-solid interaction (FSI) surface for LWPSPS-IM is lower than that of the perfect LWPSPS. In the theoretical approach, a novel analytical method is proposed to calculate the elastic constants of LWPSPS-IM. Then an engineering estimation model to predict the maximum deformation of LWPSPS-IM is developed, in which the total deformation is divided into two parts, i.e. local field deformation and global field deformation and they are both computed using analytical approach. Good agreement between the numerical results and ones obtained from the proposed analytical model is achieved.

scholarly journals Dynamic response analysis of light weight pyramidal sandwich plates subjected to water impact

2012 ◽  
Vol 19 (4) ◽  
pp. 31-43 ◽  
Author(s):  
Hao Wang ◽  
Fei Zhao ◽  
Yuan-Sheng Cheng ◽  
Jun Liu ◽  
Yuan Tian
Keyword(s):  
Estimation Method ◽  
Numerical Results ◽  
Impact Pressure ◽  
Dynamic Responses ◽  
Response Analysis ◽  
Light Weight ◽  
Water Impact ◽  
Vibration Period ◽  
Maximum Deformation ◽  
Average Water

ABSTRACT The fluid-solid interaction (FSI) dynamic responses for a Light Weight Pyramidal Sandwich Plate Structure (LWPSPS) under different water-entry velocities (1m/s-6m/s) are investigated numerically and theoretically. The characteristics of impact pressure and structure deformation are obtained by using LS-DYNA code based on the proposed 3D multi-physics (air-water-solid) FEM model. Numerical results show that the average water impact pressure of LWPSPS is much lower than that of the monolithic plate with same mass. Moreover, a phenomenon called “local air cushion” is observed for LWPSPS which does not exist for a monolithic plate. Theoretical hydroelasticity analysis demonstrates that the FSI effect of LWPSPS is weak when the ratio of water impact duration time to wet natural vibration period is greater than 4. In the study, an engineering estimation method to predict the maximum deformation of the LWPSPS is proposed, in which the total deformation is divided into two parts, i.e. local field deformation and global field deformation, and they are both computed using analytical model. Good agreement between the numerical results and ones obtained from the proposed engineering estimation method is achieved. Furthermore, the geometric variation sensitiveness analysis is also conducted.

scholarly journals Role of baffle shape on debris flow impact in step-pools channel: an SPH study

2021 ◽  
Author(s):  
Shuai Li ◽  
Chong ◽  
Wei Wu ◽  
shun wang ◽  
Xiaoqing Chen ◽  
...  
Keyword(s):  
Debris Flow ◽  
Empirical Relation ◽  
Three Dimensional ◽  
Numerical Results ◽  
Impact Pressure ◽  
Jet Flows ◽  
Flow Density ◽  
Particle Hydrodynamics ◽  
Pool System ◽  
The Impact

Drainage channels with step-pool system are widely used to control debris flow. The blocking of debris flow often gives rise to local damage at the steps and ba?es. Hence, the estimation of impact force of debris flow is crucial for designing step-pools channel. Existing empirical models for impact pressure prediction cannot consider the influence of baffle shape. In this work, a three-dimensional smoothed particle hydrodynamics (SPH) study on the impact behaviour of debris flows in step-pool systems is presented, where debris material is modelled using the regularizedBingham model. The SPH method is first checked using the results from two laboratory tests. Then it is used to investigate the influence of bafflee shape and flow density. Numerical results show that the impact pressure at the first ba?e highly depends on the ba?e shape; however, the largest impact pressure usually occurs at subsequent baffles due to the violent impact induced by jet flows. The peak impact pressure at the first ba?e initially grows with increasing flow density; however, it starts to drop as density is beyond a threshold. Based on the numerical results, an empirical relation considering the influence of ba?e shape is proposed for better prediction of debris impact pressure.

The Impact of a Flat Plate on a Water Surface

1967 ◽  
Vol 11 (04) ◽  
pp. 211-223 ◽  
Author(s):  
J. H. G. Verhagen
Keyword(s):  
Flat Plate ◽  
Water Surface ◽  
Numerical Results ◽  
Experimental Results ◽  
Impact Pressure ◽  
Drop Velocity ◽  
The Impact

The phenomena occurring during the impact of a fiat plate on a water surface are investigated both theoretically and experimentally. It is shown that, by taking the influence of the compressible air layer caught between the falling plate and the water surface properly into account, the experimental results can be fully explained. Numerical results showing the effects of falling mass, drop velocity, and plate dimensions on the maximum impact pressure are available.

Violent breaking wave impacts. Part 3. Effects of scale and aeration

2015 ◽  
Vol 765 ◽  
pp. 82-113 ◽  
Author(s):  
H. Bredmose ◽  
G. N. Bullock ◽  
A. J. Hogg
Keyword(s):  
Scaling Law ◽  
Numerical Results ◽  
Impact Pressure ◽  
Breaking Wave ◽  
Asymptotic Model ◽  
Physical Model Tests ◽  
Pressure Maximum ◽  
Air Pockets ◽  
Entrained Air ◽  
The Impact

AbstractThe effects of scale and aeration on violent breaking wave impacts with trapped and entrained air are investigated both analytically and numerically. By dimensional analysis we show that the impact pressures for Froude scaled conditions prior to the impact depend on the scale and aeration level. The Bagnold–Mitsuyasu scaling law for the compression of an air pocket by a piston of incompressible water is rederived and generalised to 3D air pockets of arbitrary shape. Numerical results for wall pressure, force and impulse are then presented for a flip-through impact, a low-aeration impact and a high-aeration impact, for nine scales and five levels of initial aeration. Two of these impact types trap a pocket of air at the wall. Among the findings of the paper is that for fixed initial aeration, impact pressures from the flip-through impact broadly follow Froude scaling. This is also the case for the two impact types with trapped air pockets for impact pressures below 318 kPa, while impact pressures above this value broadly follow the Bagnold–Mitsuyasu scaling law with full-scale pressures greater than those predicted by the Froude law. For all impact types, the effect of aeration is found to reduce the maximum impact pressure, maximum force and impulse. Good agreement with the asymptotic model of Peregrine & Thais (J. Fluid Mech., vol. 325, 1996, pp. 377–397) is found for the flip-through impact pressure and a fair agreement is found for the low- and high-aeration impacts. Based on the numerical results, a modified scaling curve that combines Froude scaling and the Bagnold–Mitsuyasu law is suggested. The practical implications of the findings are discussed and attention is drawn to the limitations of physical model tests.

scholarly journals Tracking the Fate of Aluminium in the EU Using the MaTrace Model

Resources ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 72
Author(s):  
Gabriela Jarrín Jácome ◽  
María Fernanda Godoy León ◽  
Rodrigo A. F. Alvarenga ◽  
Jo Dewulf
Keyword(s):  
Secondary Production ◽  
Economic Importance ◽  
Baseline Scenario ◽  
Light Weight ◽  
The European Union ◽  
High Corrosion Resistance ◽  
Product Categories ◽  
The Impact ◽  
Selective Collection ◽  
The Eu

Aluminium is a metal of high economic importance for the European Union (EU), presenting unique properties (e.g., light weight and high corrosion resistance) and with applications in important sectors (e.g., transportation, construction and packaging). It is also known for its high recyclability potential, but relevant losses occur in its life cycle, compromising the amount of aluminium available for secondary production. A novel methodology that allows the identification of these losses and their impact on the aluminium flows in society is the MaTrace model. The objective of this article is to perform a dMFA of the secondary production of aluminium in the EU technosphere using the modified version of MaTrace, in order to estimate flows of the metal embedded in 12 product categories. Twelve scenarios were built in order to assess the impact of changes in policies, demand and technology. The flows were forecasted for a period of 25 years, starting in 2018. The results of the baseline scenario show that after 25 years, 24% of the initial material remains in use, 4% is hoarded by users, 10% has been exported and 61% has been physically lost. The main contributor to the losses is the non-selective collection of end-of-life products. The results of the different scenarios show that by increasing the collection-to-recycling rates of the 12 product categories, the aluminium that stays in use increase up to 32.8%, reaffirming that one way to keep the material in use is to improve the collection-to-recycling schemes in the EU.

The Impact of Structural Reforms and Regulations on the Demand Side in the Railway Industry

2019 ◽  
Vol 18 (1) ◽  
pp. 1-33
Author(s):  
Fumitoshi Mizutani
Keyword(s):  
Market Structure ◽  
Vertical Integration ◽  
High Speed ◽  
Fixed Effect Model ◽  
Structural Reform ◽  
Estimation Methods ◽  
Public Ownership ◽  
Estimation Model ◽  
Passenger Demand ◽  
The Impact

Abstract The main purpose of this study is to evaluate factors affecting passenger rail demand, with special attention to the effects of structural reform/regulation and competition. In order to do this, we use data obtained from 30 OECD countries for the 24 years from 1990 to 2013. As structural reform/regulation and competition variables, we take the OECD’s five kinds of regulatory indices: (i) overall, (ii) entry, (iii) public ownership, (iv) vertical integration, and (v) market structure; and for competition variables, we take (vi) rail passenger-freight ratio, (vii) rail share, and (viii) high-speed train ratio. As estimation methods, both the fixed effect model and the Hausman-Taylor estimation model are used. The major findings are as follows. First, competition as competitiveness (i.e. the share of rail, passenger over freight ratio) increases passenger demand. And the existence of high-speed trains increases passenger demand. Second, overall, entry regulation, and market structure have no significant effect on demand. Third, public ownership affects passenger demand positively. Last, vertical integration reduces passenger demand.

Research on the Impact Pressure of the Hydraulic Rolling-Cut Shear

2010 ◽  
Vol 145 ◽  
pp. 410-413 ◽  
Author(s):  
Jing Wang ◽  
He Yong Han ◽  
Qing Xue Huang ◽  
Jun Wang
Keyword(s):  
Hydraulic System ◽  
Impact Pressure ◽  
Direct Impact ◽  
Actual Situation ◽  
Work Situation ◽  
Servo Valve ◽  
Indirect Impact ◽  
Hydraulic Servo ◽  
Hydraulic Servo System ◽  
The Impact

The reasons for impact pressure are obtained by the research the hydraulic system of Hydraulic Rolling-Cut Shear. The impact pressure of hydraulic system is divided into direct impact and indirect impact. Based on analyzing the actual situation the measures should be taken to reduce the impact pressure when design hydraulic system. The suitable length of pipeline can improve the performance of the hydraulic system because the length is important for the impact pressure. The accumulator can absorb impact pressure and improve the work situation of servo valve. Therefore, the suitable accumulators should be set in the hydraulic system. The study provides theory basis for the pipe design of large hydraulic servo system.

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