Numerical evaluation of the hydrodynamic impact characteristics of the air launched AUV upon water entry

2020 ◽  
Vol 34 (14) ◽  
pp. 2050149
Author(s):  
Ahmad Zamir Chaudhry ◽  
Guang Pan ◽  
Yao Shi
Keyword(s):  
High Speed ◽  
Impact Load ◽  
Research Work ◽  
Computational Cost ◽  
Water Entry ◽  
Structure Design ◽  
Hydrodynamic Characteristics ◽  
Ale Method ◽  
The Impact ◽  
Selection Of

In this paper, water entry process of air launched AUV is investigated by employing fully coupled finite element method and arbitrary Lagrange–Euler formulation (FEM-ALE) and using penalty coupling technique. Numerical model is established to describe the hydrodynamic characteristics and flow patterns of a high-speed water entry AUV. The effectiveness and accuracy of the numerical simulation are verified quantitatively by the experiments of the earlier study. Selection of suitable advection method and mesh convergence study is carried out during experimental validation process. It is found that appropriate mesh size of impact domain is crucial for numerical simulations and second-order Van Leer advection method is more appropriate for high speed water entry problems. Subsequently, the arbitrary Lagrange–Euler (ALE) algorithm is used to describe the variation laws of the impact load characteristics with water entry velocities, water entry angles and different AUV masses. Dimensionless impact coefficient of AUV at different velocities calculated using ALE method is compared with SPH results. This reveals that ALE method can also simulate the water entry process accurately with less computational cost. This research work can provide beneficial reference information for structure design of AUV and for selection of the water entry parameters.

scholarly journals Numerical simulation of cavitation characteristics in high speed water entry of head-jetting underwater vehicle

2021 ◽  
Vol 39 (4) ◽  
pp. 810-817
Author(s):  
Hairui Zhao ◽  
Yao Shi ◽  
Guang Pan
Keyword(s):  
Numerical Simulation ◽  
High Speed ◽  
Impact Load ◽  
Underwater Vehicle ◽  
Water Entry ◽  
Engineering Practice ◽  
Entry Angle ◽  
Air Jet ◽  
Entry Velocity ◽  
The Impact

Autonomous underwater vehicle will be subjected to a huge impact load during high speed water entry, which will damage the structure and the internal instruments of the vehicle. Therefore, it is of great significance to study the buffer mechanism of the vehicle during the process of water-entry. In this paper, a kind of head-jetting device with disk cavitation is used. The complex cavitation forms, under the three-phase coupling of gas, liquid and solid, in the water entry process of the vehicle on which the device is installed. In this paper, the numerical simulation of high-speed water entry of the vehicle equipped with head jet device is carried out. Through the analysis of water entry cavitation under typical working conditions, the following conclusions are obtained. After the installation of head jet device, the water entry cavity of the vehicle changes gradually from cone to spindle shape. The air jet, compared with that without jet, can promote the formation of water inlet supercavitation, decrease the interaction area between the vehicle and water, and reduce the impact load during water entry. At the same water entry depth, the diameter of cavitation increases with the amount of air jet. The water entry velocity has a great influence on the difference of cavitation shape. The water entry depth closure phenomenon, when the water entry velocity is less than 100 m/s, can be observed in the depth of 3.5 times of the projectile length. The water entry angle has a significant effect on the cavitation shape. The cavity shows obvious asymmetry when the vehicle slants into the water, and the diameter and length of the bubbles decrease with the increase of the water entry angle. The research content of this paper provides technical support for the engineering practice of high-speed water entry and load reduction, and the conclusions are of great significance in related fields.

scholarly journals Impact Resistance Analysis and Optimization of Variant Truss Beam Structure Based on Material Properties

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5847
Author(s):  
Xiaohao Li ◽  
Junqi Pan ◽  
Xingchen Zhou
Keyword(s):  
Simulation Analysis ◽  
Impact Load ◽  
Impact Resistance ◽  
Structure Design ◽  
Response Surfaces ◽  
Optimization Strategy ◽  
Buffer Effect ◽  
Characteristic Analysis ◽  
Beam Structure ◽  
The Impact

In order to meet the increasing application requirements with regards to structural impact resistance in industries such as mining, construction, aerospace engineering, and disaster relief and mitigation, this paper designs a variant truss beam structure with a large shrinkage ratio and high impact resistance. Based on the principle of the curved trajectory of scissor mechanisms, this paper conducts a finite element simulation analysis of the impact load on the truss beam structure, a theoretical analysis of the impact response and a relevant prototype bench-top experiment, completing a full study on the impact resistance mechanism of the designed variant truss beam structure under the impact load. In the paper, the buffer effect of the external load impact on the variant truss beam structure is analyzed from the perspective of the energy change of elastic–plastic deformation. This paper proposes an optimization strategy for the variant truss beam structure with the energy absorption rate as the optimization index through extensive analysis of the parameter response surfaces. The strategy integrates analyses on the response characteristic analysis of various configuration materials to obtain an optimal combination of component parameters that ensures that the strength of the truss beam structure meets set requirements. The strategy provides a feasible method with which to verify the effectiveness and impact resistance of a variant truss structure design.

Study on the Lateral Deformation of the Flexible Berthing Pile of High-Pile Wharf under Ship Impact Load

2015 ◽  
Vol 744-746 ◽  
pp. 1184-1187
Author(s):  
Qiu Zhai ◽  
Wen Xiang ◽  
Yu Li
Keyword(s):  
Iterative Method ◽  
Analytical Method ◽  
Impact Load ◽  
Correlation Coefficients ◽  
Structure Design ◽  
Horizontal Force ◽  
Lateral Deformation ◽  
Mathematical Formula ◽  
The Impact

Flexible berthing pile-high pile wharf is a system which is composed of flexible berthing pile, rubber fender and pile platform. The system was divided into two forms based on the pile platform sustained the impact load or not. The method to analysis the lateral deformation of the pile was relatively mature when the platform was subjected to the impact load. Instead, when the pile platform is subjected to the impact load, the analytical method is unsatisfactory because of the complexity about the lateral deformation of the system. This paper takes the second condition as the research object, and study the lateral deformation of the pile, rubber fender and the pile platform. The mathematical formula is built on the horizontal force balancing condition and displacement coordination at the top of pile, the method to evaluate the correlation coefficients of the formulas is suggested, and the steps that solve the formulas by iterative method are described. The theory is clear, and the result can offer a reference for structure design and code revision.

scholarly journals Finite Element Analysis of Impact Energy on Spur Gear

2018 ◽  
Vol 225 ◽  
pp. 06011 ◽  
Author(s):  
Ismail Ali Bin Abdul Aziz ◽  
Daing Mohamad Nafiz Bin Daing Idris ◽  
Mohd Hasnun Arif Bin Hassan ◽  
Mohamad Firdaus Bin Basrawi
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Impact Energy ◽  
High Speed ◽  
Impact Test ◽  
Impact Load ◽  
Gear Tooth ◽  
Test Equipment ◽  
Element Analysis ◽  
The Impact

In high-speed gear drive and power transmission, system impact failure mode always occurs due to the sudden impact and shock loading during the system in running. Therefore, study on the amount of impact energy that can be absorbed by a gear is vital. Impact test equipment has been designed and modelled for the purpose to study the impact energy on gear tooth. This paper mainly focused on Finite Element Analysis (FEA) of impact energy that occurred during simulation involving the impact test equipment modelling. The simulation was conducted using Abaqus software on critical parts of the test equipment to simulate the impact event and generate impact data for analysis. The load cell in the model was assumed to be free fall at a certain height which gives impact load to the test gear. Three different type of material for the test gear were set up in this simulation. Results from the simulation show that each material possesses different impact energy characteristic. Impact energy values increased along with the height of load drop. AISI 1040 were found to be the toughest material at 3.0m drop that could withstand up to 44.87N.m of impact energy. These data will be used to validate data in physical experiments in further study.

Research on the Impact of Vent Pressure on the Yarn Splicing Based on ANSYS

2013 ◽  
Vol 584 ◽  
pp. 50-53
Author(s):  
De Gong Chang ◽  
Deng Chen Li ◽  
Song Mei Li ◽  
Guang Zhen Zhou ◽  
Hai Xia Zhao
Keyword(s):  
Driving Force ◽  
High Speed ◽  
Structure Design ◽  
Hole Diameter ◽  
Ansys Software ◽  
Modeling Analysis ◽  
Solid Foundation ◽  
The Impact ◽  
Chamber Diameter

Pneumatic splice makes use of high-speed compressed air as the driving force to complete the yarn splicing, noticing that the change of the vent pressure has a significant effect on yarn splicing. This paper studies the impact of vent pressure on the quality of yarn splicing when twisting and untwisting. Modeling, analysis and simulation of the air splice is done with the integration of Pro/E and ANSYS software, to study the flow filed and obtain the influence on the speed and pressure of the inside the splicing chamber when changing the speed and pressure while keeping the diameter of splicing chamber diameter, the vent hole diameter and the relative angle are unchanged. The results of the analysis of the air splice will lay a solid foundation for the further optimized structure design.

scholarly journals Flexible-Rigid Wheelset Introduced Dynamic Effects due to Wheel Tread Flat

2021 ◽  
Vol 2021 ◽  
pp. 1-21
Author(s):  
Awel Momhur ◽  
Y. X. Zhao ◽  
Liwen Quan ◽  
Sun Yazhou ◽  
Xialong Zou
Keyword(s):  
High Speed ◽  
Statistical Approach ◽  
Impact Load ◽  
Vertical Acceleration ◽  
Vehicle Speed ◽  
Dynamic Impact ◽  
Element Analysis ◽  
Wheel Flat ◽  
Wheel Radius ◽  
The Impact

The widespread faults that occur in railway wheels and can cause a massive dynamic impact are the wheel tread flat. The current work considered changes in vehicle speed or wheel radius deviation and studied the dynamic impact load. The modal technique for the impact evaluation induced by the wheel flat was proposed via the finite element analysis (FEA) software package ANSYS, integrated into a multibody dynamics model of the high-speed train CRH2A (EMU) through SIMPACK. The irregularity track line has developed and depends on the selected simulation data points. Additionally, a statistical approach is designed to analyze the dynamic impact load response and effect and consider different wheel flat lengths and vehicle speeds. The train speed influence on the flat size of the vertical wheel-rail impact response and the statistical approach are discussed based on flexible, rigid wheelsets. The results show that the rigid wheel flat has the highest vertical wheel impact load and is more significant than the flexible wheel flat force. The consequences suggest that the wheelset flexibility can significantly improve vertical acceleration comparably to the rigid wheel flats. In addition, the rendering of the statistical approach shows that the hazard rate, PDF, and CDF influence increase when the flat wheel length increases.

Energy Absorption of All-Metallic Corrugated Sandwich Cylindrical Shells Subjected to Axial Compression

2020 ◽  
Vol 87 (12) ◽  
Author(s):  
Pengbo Su ◽  
Bin Han ◽  
Mao Yang ◽  
Zhongnan Zhao ◽  
Feihao Li ◽  
...  
Keyword(s):  
Energy Absorption ◽  
Axial Compression ◽  
High Speed ◽  
Impact Load ◽  
Cylindrical Shells ◽  
Dynamic Effect ◽  
Absorption Capacity ◽  
Amplification Coefficient ◽  
Displacement Curve ◽  
The Impact

Abstract The energy adsorption properties of all-metallic corrugated sandwich cylindrical shells (CSCSs) subjected to axial compression loading were investigated by the method combining experiments, finite element (FE) simulations, and theoretical analysis. CSCS specimens manufactured using two different methods, i.e., high-speed wire-cut electric discharge machining (HSWEDM) and extrusion, were tested under axial compression. While specimens fabricated separately by HSWEDM and extrusion both exhibited a stable crushing behavior, the extruded ones were much more applicable as lightweight energy absorbers because of their good energy absorption capacity, repeatability, and low cost. The numerically simulated force–displacement curve and the corresponding deformation morphologies of the CSCS compared well with those obtained from experiments. The specific folding deformation mode was revealed from both experiments and simulations. Subsequently, based upon the mode of folding deformation, a theoretical model was established to predict the mean crushing force of the CSCS construction. It was demonstrated that CSCSs with more corrugated units, smaller value of tc/tf and W/Ro could dissipate more impact energy. Such sandwich cylindrical shells exhibited better energy absorption than monolithic cylindrical shells, with an increase of at least 30%. Ultimately, the dynamic effect under the impact load was further evaluated. The dynamic amplification coefficient of CSCS decreased with the increase of the wall thickness.

Dynamic Analysis of Pitch Plane Railway Vehicle-Track Interactions Due to Single and Multiple Wheel Flats

2008 ◽  
Author(s):  
Rajib Ul Alam Uzzal ◽  
Subhash Rakheja ◽  
Waiz Ahmed
Keyword(s):  
Parametric Study ◽  
High Speed ◽  
Impact Load ◽  
Critical Length ◽  
Hertzian Contact ◽  
Railway Vehicle ◽  
Main Concern ◽  
Track System ◽  
Wheel Flat ◽  
The Impact

The dynamic impact forces due to the wheel defect such as a flat is a main concern for a heavy freight train operating at high speed. The present investigation employs a pitch plane vehicle model coupled with a comprehensive three-layer track system model to study the impact force generated in the wheel-rail interface due to the presence of wheel flats. The wheel-rail contact is modeled using nonlinear Hertzian contact theory. Responses in terms of wheel-rail impact load and forces transmitted to bearings, pad and ballast are evaluated in an attempt to identify desirable design and operating factors. Wheel-rail impact loads due to the presence of multiple flats either in single or different wheels in-phase or out-of-phase conditions are evaluated and analyzed. A detailed parametric study is carried out that includes the variations in selected vehicle, track, operational as well as flat parameters. The results show that the effect of multiple flats is insignificant if they are more than 45° apart. The impact due to single wheel flat can be larger than in-phase flats at each wheel due to the presence of pitch dynamics. The parametric study shows that other than speed, depth and length of the flats are most sensitive parameters, and there exists a critical length at each flat depth that leads to the largest impact load.

Study on Safety Measures for Construction of Foundation Pit close to Existing Railway Lines

2012 ◽  
Vol 178-181 ◽  
pp. 1279-1286 ◽  
Author(s):  
Xiao Hui Zhang ◽  
Quan Mei Gong ◽  
Shun Hua Zhou
Keyword(s):  
High Speed ◽  
Cost Effective ◽  
Structure Design ◽  
Foundation Pit ◽  
High Speed Railway ◽  
Reinforcement Measures ◽  
Railway Operation ◽  
The Cost ◽  
Effective Reinforcement ◽  
The Impact

The finite-element method is adopted to analyze the impact of foundation pit construction on close-by railway lines, and related measures are studied to ensure the safety of railway operation during the pit construction. Eventually, cost-effective reinforcement method is recommended, therefor providing a reference for construction of similar foundation pit close to railway lines to determine reinforcement method. The conclusions indicate that under the existing structure design and basal reinforcement design of the foundation pit, the largest settlement of high-speed railway lines is 23.48mm, which does not meet the relative requirements. To reduce the settlement, three rows of high pressure jet grouting piles reinforcement outside the foundation pit and 0.15m away from waterproof curtain is recommended, and 18.0m is considered as the cost-effective reinforcement depth. With the effect of the proposed reinforcement measures, the largest settlement magnitude of high-speed railway subgrade is reduced by 25% to 14.0mm, which meets the relative requirement.

Dynamic and Quasi-Static Compression Tests for Polylactic Acid Resin Foam

2012 ◽  
Vol 706-709 ◽  
pp. 745-750 ◽  
Author(s):  
Hidetoshi Kobayashi ◽  
Keitaro Horikawa ◽  
Keiko Watanabe ◽  
Kinya Ogawa ◽  
Kensuke Nozaki
Keyword(s):  
Strain Rate ◽  
Polylactic Acid ◽  
High Speed ◽  
Impact Load ◽  
Video Camera ◽  
Compression Tests ◽  
Rate Dependency ◽  
Static Compression ◽  
Acid Resin ◽  
The Impact

In this study, the effect of strain rate on the strength and the absorbed energy of polylactic acid resin foam (PLA-foam), which is generally known as one of carbon-neutral and environmentally-friendly polymers, were examined by a series of compression tests at various strain rates from 0.001 to 750 s-1. For the measurements of the impact load and the displacement of specimen, a special load cell and a high-speed video camera were used, respectively. The flow stress of the PLA-foam strongly depends upon not only strain rate but also density of specimens. Thus, a new technique to eliminate the effect of the difference in the specimen density was proposed and successfully applied. It was also found that the strain-rate dependency of PLA-foam can be expressed by a simple power law.

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