Influence of Imperfection on Dynamic Response of Cross-Stiffened Deck Subjected to In-Plane Impact

2014 ◽  
Author(s):  
Zhen-hua Ji ◽  
De-yu Wang
Keyword(s):  
Dynamic Response ◽  
Ultimate Strength ◽  
Impact Load ◽  
Severe Condition ◽  
Vibration Period ◽  
Geometric Imperfection ◽  
Negative Deflection ◽  
Deck Plate ◽  
The Impact ◽  
Impact Duration

The motivation of this research is that the ship deck is subjected to uni-axial compression under sagging condition, when in the severe condition, the deck is dynamically loaded in nature, with impact type loads, which is the reason of deck collapse under severe condition. In addition, imperfection probably substantially influences the dynamic response of the impacted deck. Based on nonlinear explicit finite element method, the paper aims at studying the influence of three types of initial geometric imperfection on dynamic response of cross-stiffened deck subjected to in-plane impact. Three types of imperfection are local imperfection on deck plate between stiffeners, imperfection of overall positive deflection of the deck, and imperfection of overall negative deflection of the deck. Impact function is a half sine wave function with two parameters, impact duration and amplitude of the impact load. First order natural vibration period of the deck is selected as impact duration. Amplitude of the impact load is selected according to the value of ultimate strength of the deck, and varied by times of the ultimate strength. Strain rate effect and Strain hardening effect of the material are accounted in the analysis. Axial residual displacement of the end of the deck after impact is selected as dynamic response of the deck. The result shows that dynamic response of deck is sensitive to local imperfection, while not sensitive to overall imperfection under low or moderate level of imperfection magnitude. When imperfection is severe, residual axial displacement of the end of the deck is large, especially amplitude of impact load is somewhat larger than ultimate strength. Among 3 kinds of imperfection, dynamic response of overall negative deflection imperfection is the largest, followed by that of local imperfection, while that of overall positive deflection imperfection is the least.

Dynamic Ultimate Strength Characteristics of Stiffened Plates Subjected to the In-Plane Impact Load and Lateral Pressure

2021 ◽  
Author(s):  
Qiang Zhong ◽  
De-yu Wang
Keyword(s):  
Finite Element ◽  
Ultimate Strength ◽  
Lateral Pressure ◽  
Impact Load ◽  
Strength Characteristics ◽  
Stiffened Plates ◽  
Strength Theory ◽  
Explicit Finite Element ◽  
Static Conditions ◽  
The Impact

Abstract Dynamic capacity is totally different from quasi-static capacity of ship structural components, although most ultimate strength analyses at present by researchers are performed under quasi-static conditions. To investigate the dynamic ultimate strength characteristics, the dynamic ultimate strength analyses of stiffened plates subjected to impact load were studied based on a 3-D nonlinear explicit finite element method (FEM) in this paper. The impact load in the present work is characterized as a half-sine function. A series of nonlinear finite element analyses are carried out using Budiansky-Roth (B-R) criterion. The influence of impact durations, model ranges, boundary conditions, initial imperfections and impact loads on the dynamic ultimate strength of stiffened plates are discussed. In addition, the ultimate strength of stiffened plates under the in-plane impact combined with lateral pressure was also calculated, which shows lateral pressure has a negligible effect on the dynamic ultimate strength of stiffened plates subjected to the impact load with short durations. Other important conclusions can be obtained from this paper, which are useful insights for the development of ultimate strength theory of ship structures and lay a good foundation for the study of dynamic ultimate strength in the future.

Finite Element Analysis of a Single-Layer Reticulated Dome under Impact Loading

2010 ◽  
Vol 163-167 ◽  
pp. 327-331 ◽  
Author(s):  
Liang Zheng ◽  
Zhi Hua Chen
Keyword(s):  
Finite Element ◽  
Dynamic Response ◽  
Impact Force ◽  
Impact Load ◽  
Residual Deformation ◽  
Time History ◽  
Single Layer ◽  
Element Analysis ◽  
Deformation Stage ◽  
The Impact

Finite element model of both the single-layer Schwedler reticulated dome with the span of 50m and a Cuboid impactor were developed, incorporating ANSYS/LS-DYNA. PLASTIC_KINEMATIC (MAT_003) material model which takes stain rate into account was used to simulate steel under impact load. The automatic point to surface contact (NODES TO SURFACE) was applied between the dome and impact block. Three stages of time history curve of the impact force on the apex of the single-layer Scheduler reticulated dome including the impact stage, stable stalemate stage, the decaying stage were generalized according to its dynamic response. It must be pointed out that the peak of the impact force of the single-layer reticulated dome increase with the increase of the weight and the velocity of the impact block, but the change of the velocity of the impact block is more sensitive than the change of weight of the impact block for the effect of the peak of the impact force, and a platform value of the impact force of the single-layer reticulated dome change near a certain value, and the duration time of the impact gradually increase. Then four stages of time history curve of the impact displacement were proposed according to the dynamic response of impact on the apex of the single-layer reticulated dome based on numerical analysis. Four stages include in elastic deformation stage, plastic deformation stage, elastic rebound stage, free vibration stage in the position of the residual deformation.

Numerical Simulation and Experimental Study on Fluid-Filled Hemispherical Shell under Impact

2013 ◽  
Vol 364 ◽  
pp. 172-176
Author(s):  
Hui Wei Yang ◽  
Bin Qin ◽  
Zhi Jun Han ◽  
Guo Yun Lu
Keyword(s):  
Numerical Simulation ◽  
Dynamic Response ◽  
Impact Load ◽  
Elastic Recovery ◽  
Plastic Hinge ◽  
Time History ◽  
Hemispherical Shell ◽  
History Of ◽  
Local Impact ◽  
The Impact

The dynamic response of fluid-filled hemispherical shell in mass impact is studied by experiment using DHR9401. Combining the time history of impact force with experimental observation of the deformation process, it can be seen that the dynamic response can be divided into four stages: the flattening around the impact point, the forming and expanding outward of shell plastic hinge, the plastic edge region flatten by the punch, and elastic recovery. The experimental results show that: Because the shell filled with liquid, the local impact load that the shell suffered is translated into area load and loads on the inner shell uniformly, so that it has a high carrying capacity. Numerical simulation is used to study the time history of energy absorption of different shell structures. The result shows that the crashworthiness of sandwich fluid-filled shell is improved greatly. Under the certain impact energy, deformation of its inner shell is very small, which can provide effective security space.

Hailstone-induced dynamic responses of pretensioned umbrella membrane structure

2020 ◽  
Vol 24 (1) ◽  
pp. 3-16 ◽  
Author(s):  
Changjiang Liu ◽  
Fan Wang ◽  
Xiaowei Deng ◽  
Song Pang ◽  
Jian Liu ◽  
...  
Keyword(s):  
Dynamic Response ◽  
Membrane Structure ◽  
Impact Analysis ◽  
Impact Load ◽  
Dynamic Responses ◽  
Flexible Structure ◽  
Membrane Material ◽  
Membrane Structures ◽  
Characteristic Points ◽  
The Impact

The membrane structure is a flexible structure, which is easy to vibrate or even relax under dynamic load. Engineering accident analysis shows that the relaxation of membrane structure is more likely to lead to structural failure. In this article, the impact load problem is combined with the flexible structure to analyze the impact of hailstone impact load on the dynamic response of membrane structure. First, the umbrella membrane stretching device was designed and manufactured, and the hailstone impact test was carried out on the umbrella membrane structure with polyvinyl chloride membrane material. Dynamic response data, tension relaxation of side cables and vibration deformation of umbrella membrane structures impacted by hailstones with different sizes and different characteristic points were obtained. In the numerical analysis, the form-finding analysis of umbrella membrane structure is carried out by finite element method, and the transient impact analysis is conducted in LS-DYNA. Finally, the reliability of the research results is verified by comparing the numerical and experimental results. The general laws and conclusions are drawn and the disaster-causing mechanism of membrane structure impacted by hailstone is revealed. On the whole, although the probability of hailstone destroying the membrane material directly is very small, it will relax the membrane structure and affect the safety of membrane structure. The conclusions of this article provide a theoretical basis for the design and maintenance of membrane structures.

Analysis of Dynamic Response of Mine Rescue Chamber under Axial Impact Load

2011 ◽  
Vol 211-212 ◽  
pp. 576-580 ◽  
Author(s):  
Ming Song ◽  
Shi Rong Ge ◽  
Hai Feng Fang
Keyword(s):  
Dynamic Response ◽  
Impact Load ◽  
Element Model ◽  
Deformation Energy ◽  
Spherical Shells ◽  
Tunnel Wall ◽  
Axial Impact ◽  
Plate And Shell ◽  
The Impact ◽  
Mine Rescue

In order to research the problem of rescue chamber colliding with the tunnel wall. The theoretical model of rescue chamber has been formed, based on the principle of energy conservation, by using theories of plates and shells, large deformed plate and shell, and by analysis of dynamic response of mine rescue chamber under axial impact load. This model includes initial velocity, contact force deformation energy and shell deformation. Dytran software was applied to build the finite element model of the rescue chamber contacting the rigid plate. Through comparison emulation result and theoretical analysis result, this model is proved to be highly reliable. The theoretical calculation and the simulation indicated that there were obvious relationships among the ability of the mine rescue chamber under axial impact load with the thickness, depth of flat spherical shells. If the thickness or depth increases, then the chamber could stand more. It is also confirmed that increasing the depth of flat spherical shells can minish the impact force for making impact process abate, which provides a basis for the research of rescue chamber.

Evaluation of Dynamic Property of Radiogram under Repetitive Drop Shock

2011 ◽  
Vol 101-102 ◽  
pp. 1087-1091
Author(s):  
Yan Feng Guo ◽  
Yan Hong Mao ◽  
Yun Gang Fu ◽  
Wen Cai Xu
Keyword(s):  
Natural Vibration ◽  
Amplification Factor ◽  
Impact Load ◽  
Railway Transportation ◽  
Electronic Components ◽  
Box Structure ◽  
Repetitive Impact ◽  
The Impact ◽  
And Storage ◽  
Impact Duration

Repetitive impact during highway and railway transportation has potential and severe harm for the product with fragile or damageable component. The radiogram belongs to a typical electronic product with panel and box structure, and occurs with the falling down of loudspeaker contacted on the top box, the failure of electronic components, and the fracture of outside box during transportation and storage. So the main feature of this article is the analysis on the natural vibration property, and the evaluation on the drop shock property including amplification factor and relevant curves under nine kinds of repetitive impact with different impact duration and drop height. The results show that the amplification factor markedly rise while the impact duration 2.02ms (nearly causing the resonance of radiogram), the repetitive drop shock may bring more serious damage than single impact load, so the case should be paid attention for the design of package cushioning.

Analysis on the Effect of Input Impact Profiles in Drop Test

2007 ◽  
Author(s):  
Jiang Zhou ◽  
Ratna P. Niraula ◽  
Kendrick Aung
Keyword(s):  
Dynamic Response ◽  
Impact Load ◽  
Block Diagram ◽  
Input Pulse ◽  
Drop Test ◽  
System Level ◽  
System Response ◽  
Time Duration ◽  
Board Level ◽  
The Impact

The objective of this paper is to develop an analytical or mathematical predicative model for the evaluation of dynamic response of a structural element in a microelectronic or an optoelectronic product to an impact load occurring as a result of drop or shock test. Closed-form theoretical solution was obtained to simulate the board level drop test. The block diagram based SIMULINK analysis was introduced to determine the response with various impact configurations for the system level drop test as well. This study will help reliability engineers to design the impact input profiles and obtain the desired responses, and to calibrate and validate finite element analysis results quickly for both board level and system level drop test. It was found that time durations of the input profiles play an important role in the dynamic response. The system response can be designed by carefully choosing the impact time duration. Certain input pulse time results in the response with very low ringing after first or second peaks.

scholarly journals The effect of high-frequency torsional impacts on the dynamic response of a drill string in a stick state

2019 ◽  
Vol 11 (3) ◽  
pp. 168781401982857
Author(s):  
Liping Tang ◽  
Wei He ◽  
Xiaohua Zhu
Keyword(s):  
Dynamic Response ◽  
High Frequency ◽  
Impact Load ◽  
Drill String ◽  
Superposition Method ◽  
Drill Bit ◽  
Stick Slip ◽  
Mode Superposition Method ◽  
Study Results ◽  
The Impact

Stick–slip vibration is common in the oil well drilling process and is detrimental to down-hole equipment and drilling efficiency. In recent years, a new type of drilling technology, torsional impact drilling, has been developed to mitigate the stick–slip phenomena, particularly in the drilling of deep or abrasive formations. With this drilling technique, high-frequency torsional impacts are generated and applied to the drill bit, providing the drill bit with auxiliary energy. By mitigating or suppressing the stick–slip vibration, part of the energy wasted as a result of vibration can be regained. However, the effect of these impact loads on the dynamic response of a drill string in a stick state is unknown. In order to address this issue, a continuous system model of a drill string that includes torsional impact load was constructed. In the model, a Fourier series approach was used for the impact load, and the mechanical model was resolved with the mode superposition method. Case studies were done to understand the drill string dynamics, with and without the impact. The case study results demonstrate that high-frequency torsional impacts have little influence on the dynamic response of a drill string in a stick state.

A New Method to the Elastodynamic Response of a Spherical Shell Under the Impact Load

2016 ◽  
Vol 138 (3) ◽  
Author(s):  
Shugen Xu ◽  
Yang Wei ◽  
Chong Wang ◽  
Weiqiang Wang
Keyword(s):  
Wave Equation ◽  
Dynamic Response ◽  
Boundary Conditions ◽  
Spherical Shell ◽  
Solution Structure ◽  
Structure Theorem ◽  
Impact Load ◽  
Structural Dynamic ◽  
Elastodynamic Response ◽  
The Impact

In this paper, a new methodology for solving response of a spherical shell based on developed solution structure theorem has been proposed. It can be used to solve the wave equation about the structural dynamic response of a spherical shell under the impact pressure. The proposed method can be used to solve a batch of partial differential equations having the similar governing equation with different initial and boundary conditions. A detailed solving procedure has been provided to show how to use this method correctly. Finally, a practical example is provided to show how to use the proposed method to solving the elastodynamic response of a spherical shell under inner impact load.

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