Optimization of the Shock Mitigation Layer in the Space Frame Joints of an Armored Vehicle

2013 ◽  
Author(s):  
Jagadeep Thota ◽  
Mohamed Trabia ◽  
Brendan O’Toole ◽  
Chang-Hyun Lee ◽  
Hong-Lae Park ◽  
...  
Keyword(s):  
Structural Integrity ◽  
Random Search ◽  
Quadratic Approximation ◽  
Frame Structure ◽  
Optimization Process ◽  
Internal Space ◽  
Space Frame ◽  
Beam Elements ◽  
Shock Mitigation ◽  
Armored Vehicle

Armored vehicles have to survive multiple threats such as projectile or land mines. The shocks induced by these threats can harm vehicle occupants or damage sensitive electronic components. Therefore, a goal of modern armored vehicle design is to reduce transmitted shocks to critical components. In this paper, finite element (FE) models of an armored vehicle prototype having the internal space frame structure with the aforementioned features are developed. One model comprises of only solid elements, while another model is created with purely beam elements. The beam elements model is used for optimization studies whose objective is to reduce the shocks within the vehicle, due to mine blast while maintaining its overall structural integrity. The thickness of the rubberized shock mitigation layer at the joints of the space frame is varied during the optimization process. The optimization problem is solved using the Successive Heuristic Quadratic Approximation (SHQA) algorithm, which combines successive quadratic approximation with an adaptive random search while varying the bounds of the search space. The entire optimization process is carried out within the MATLAB environment. The results show that a significant reduction in the shock can be achieved using this approach.

Shock Optimization in a Military Vehicle With Internal Space Frame

2009 ◽  
Author(s):  
Jagadeep Thota ◽  
Mohamed B. Trabia ◽  
Brendan J. O’Toole
Keyword(s):  
Structural Integrity ◽  
Impact Load ◽  
Random Search ◽  
Search Space ◽  
Quadratic Approximation ◽  
Internal Space ◽  
Space Frame ◽  
Military Vehicles ◽  
Space Frames ◽  
Mine Blasts

Space frames are usually used to enhance structural strength of the vehicle while reducing its overall mass. These frames are comprised of beams that are joined together. Recently, space frames are being incorporated in military vehicles. Space frames in military vehicles are however subjected to different types of loading than what is encountered in civilian vehicles such as projectile impacts and land mine blasts. Due to the need to replace a damaged section of the space frame quickly, the proposed space frame is composed of hollow square cross-section bars and angle sections that are bolted together. The space frame is enclosed by uniform-thickness armor, except at the turret. The vehicle is subjected to high impact load to simulate a projectile hit. The objective of this work is to minimize shocks at various critical locations of the space frame while maintaining the overall structural integrity of the vehicle. The vehicle model is parameterized to achieve this objective. This problem is solved using the Successive Heuristic Quadratic Approximation (SHQA) technique, which combines successive quadratic approximation with an adaptive random search within varying search space. The entire optimization process is carried out within MATLAB environment.

Optimization of a Military Vehicle Space Frame Subject to High Impact Loading

2008 ◽  
Author(s):  
Jagadeep Thota ◽  
Mohamed B. Trabia ◽  
Brendan J. O’Toole
Keyword(s):  
Structural Integrity ◽  
Impact Load ◽  
Random Search ◽  
Element Model ◽  
Search Space ◽  
High Impact ◽  
Quadratic Approximation ◽  
Space Frame ◽  
Cross Sectional ◽  
Space Frames

Space frames are usually used to enhance structural strength of the vehicle while reducing its overall weight. These frames are comprised of beams connected together at joints. Recently, space frames are incorporated in military vehicles. However, space frames in this case are subjected to different types of loading than what is encountered in civilian vehicles such as, projectile and land mine attacks. In this paper, a finite element model for the upper half of the space frame of an armored vehicle is developed. The space frame is composed of hollow square cross-section bars and angle sections and is enclosed by uniform-thickness armor, except at the turret. The vehicle is subjected to high impact load that simulates an impact of a projectile. The model is parameterized to minimize the mass of the space frame and vehicle armor by varying the cross-sectional parameters of the beam members and joints, and the thickness of the armor plate, while maintaining the overall structural integrity of the space frame. This problem is solved using the Successive Heuristic Quadratic Approximation (SHQA). This algorithm combines successive quadratic approximation with an adaptive random search within varying search space. The entire optimization process is carried out within MATLAB environment. Results show significant reduction of the mass of the vehicle.

Optimization of a Vehicle Space Frame Under Ballistic Impact Loading

2007 ◽  
Author(s):  
Umakanth Sakaray ◽  
Mohamed B. Trabia ◽  
Brendan J. O’Toole ◽  
Jagadeep Thota
Keyword(s):  
Impact Loading ◽  
Structural Integrity ◽  
Element Model ◽  
Stress Constraints ◽  
Frame Structure ◽  
Mass Reduction ◽  
Electronic Components ◽  
Space Frame ◽  
Military Vehicle ◽  
Joint Location

Shock from impact loading may risk the lives of the occupants of a military vehicle and damage the sensitive electronic components within it. A finite element model (FEM) for a space-frame based military vehicle is presented in this paper. An approach is developed to optimize the design of the joints within the space frame structure to reduce the mass of the vehicle while maintaining its structural integrity. The process starts by creating a parametric FEM of the vehicle. The optimization variables are the lengths of joint branches. The effect of joint location within the space frame is also explored. The problem is subject to geometry and stress constraints. Results show that a mass reduction can be achieved without adversely affecting integrity of the vehicle.

Shock Mitigation by Energy Reversal to the High Frequency Modes

2014 ◽  
Author(s):  
Mohammad A. AL-Shudeifat ◽  
Alexander F. Vakakis ◽  
Lawrence A. Bergman
Keyword(s):  
High Frequency ◽  
Large Scale ◽  
Computational Study ◽  
Dynamic Structure ◽  
Frequency Mode ◽  
Frame Structure ◽  
Shock Energy ◽  
Modal Damping ◽  
Shock Mitigation ◽  
High Frequency Modes

In this computational study, a light-weight dynamic device is investigated for passive energy reversal from the lowest frequency mode to the high frequency modes of a large-scale frame structure for rapid shock mitigation. The device is based on the single-sided vibro-impact mechanism. It has two functions for passive energy transfer: a nonlinear energy sink (NES) for local energy dissipation and an energy pump to high frequency modes where a significant amount of the shock energy is rapidly dissipated. As a result, a significant portion of the shock energy induced into the linear dynamic structure can be passively reversed from the lowest frequency mode to the high frequency modes and rapidly dissipated by their modal damping. The amount of the energy dissipated by the modal damping of the high frequency modes can be controlled by the amount of inherent damping in the device. Ideally, the device can passively reverse up to 80% of the input shock energy from the lowest frequency mode to the high frequency modes when its damping is assumed to be zero and its impact coefficient of restitution is equal to unity. The shock energy redistribution between this device and the high frequency modes is found to be efficient for rapid shock mitigation in the considered 9-story dynamic structure.

Optimization of the Closure-Weld Region of Cylindrical Containers for Long-Term Corrosion Resistance Using the Successive Heuristic Quadratic Approximation Technique*

2003 ◽  
Vol 125 (3) ◽  
pp. 533-539 ◽  
Author(s):  
Zekai Ceylan ◽  
Mohamed B. Trabia
Keyword(s):  
Finite Element ◽  
Random Search ◽  
Nonlinear Problems ◽  
Search Space ◽  
Induction Coil ◽  
Quadratic Approximation ◽  
Approximation Technique ◽  
General Corrosion ◽  
Highly Nonlinear

Welded cylindrical containers are susceptible to stress corrosion cracking (SCC) in the closure-weld area. An induction coil heating technique may be used to relieve the residual stresses in the closure-weld. This technique involves localized heating of the material by the surrounding coils. The material is then cooled to room temperature by quenching. A two-dimensional axisymmetric finite element model is developed to study the effects of induction coil heating and subsequent quenching. The finite element results are validated through an experimental test. The container design is tuned to maximize the compressive stress from the outer surface to a depth that is equal to the long-term general corrosion rate of the container material multiplied by the desired container lifetime. The problem is subject to several geometrical and stress constraints. Two different solution methods are implemented for this purpose. First, an off-the-shelf optimization software is used. The results however were unsatisfactory because of the highly nonlinear nature of the problem. The paper proposes a novel alternative: the Successive Heuristic Quadratic Approximation (SHQA) technique. This algorithm combines successive quadratic approximation with an adaptive random search within varying search space. SHQA promises to be a suitable search method for computationally intensive, highly nonlinear problems.

Optimization of the Closure-Weld Region of Cylindrical Containers for Long-Term Corrosion Resistance

2001 ◽  
Author(s):  
Zekai Ceylan ◽  
Mohamed B. Trabia
Keyword(s):  
Finite Element ◽  
Random Search ◽  
Element Model ◽  
Stress Constraints ◽  
Induction Coil ◽  
Quadratic Approximation ◽  
General Corrosion ◽  
Highly Nonlinear ◽  
Weld Area

Abstract Welded cylindrical containers usually experience stress corrosion cracking (SCC) in the closure-weld area. Induction coil heating technique may be used to relieve the residual stresses from the closure-weld. This technique involves localized heating of the material by the surrounding coils. The material is then cooled to the room temperature by quenching. A two-dimensional axisymmetric finite element model is developed to study the effects of induction coil heating and subsequent quenching. The finite element results are validated through an experimental test. The parameters of the design are tuned to maximize the compressive stress within a layer of thickness from the outer surface that is equal to the long-term general corrosion of Alloy 22 (Appendix A). The problem is subject to geometrical and stress constraints. Two different solution methods are implemented for this purpose. First, an off-the-shelf optimization software is used to obtain an optimum solution. These results are not satisfactory because of the highly nonlinear nature of the problem. The paper proposes a novel alternative: the Successive Heuristic Quadratic Approximation (SHQA) technique. This algorithm combines successive quadratic approximation with an adaptive random search. Examples and discussion are included.

Piping System Structural Integrity Simulation for Post LOCA Water Hammer Loads

2002 ◽  
Author(s):  
B. W. Manning ◽  
T. Stevens ◽  
G. Morandin ◽  
R. G. Sauve´ ◽  
R. Richards ◽  
...  
Keyword(s):  
Structural Damage ◽  
Structural Integrity ◽  
Water Hammer ◽  
Piping System ◽  
Linear Modeling ◽  
Linear Elastic ◽  
Beam Elements ◽  
Loss Of Coolant Accident ◽  
Loss Of Coolant ◽  
Non Linear

The Canadian Nuclear Safety Commission (CNSC) required as part of the operating license for Ontario Power Generation’s Darlington Nuclear Generating Station, that the structural integrity of the piping following a loss of coolant accident (LOCA) be demonstrated. This is necessary to ensure that no subsequent pressure boundary failures will impede the ability to maintain fuel cooling. The injection of cold emergency coolant following a LOCA creates the potential for the occurrence of condensation-induced water hammers (CIWH) in the primary heat transport (PHT) system piping. Classical linear elastic piping analysis using the class 1 NB-3656 rules of the ASME Boiler & Pressure Vessel Code failed to demonstrate the adequacy of the piping and/or its supports that were designed using the linear elastic rules of subsection NF for nine of the twelve piping models that comprise the PHT system. A decision was made to undertake a state-of-the-art non-linear explicit analysis in order to qualify the piping. Strain rather than stress limits would be applied similar to those being developed by ASME for nuclear packaging undergoing accidental impact during transportation. In order to address the feasibility of this approach, a non-linear analysis was performed on a portion of one of the piping systems. The piping was modeled as shells and again as beam elements with and without detailed modeling of the supports. After these initial simulations, it was determined that the piping could be modeled with simplified beam elements, however, the supports would require a more detailed modeling in order to determine the extent of support damage and the effect the supports have on the integrity of the piping system itself. This paper addresses the non-linear modeling of the piping models and discusses the modeling details, assumptions and analysis results. This approach is shown to be a useful alternative for predicting the extent of structural damage that can be expected by a Level D event such as a condensation induced water hammer following a loss of coolant accident.

Solution method for ill-conditioned problems based on a new improved fruit fly optimization algorithm

2020 ◽  
Vol 14 (1) ◽  
pp. 55-64
Author(s):  
Qian Fan ◽  
Xiaolin Meng ◽  
Chengquan Xu ◽  
Jiayong Yu
Keyword(s):  
Optimization Algorithm ◽  
Random Search ◽  
Estimation Method ◽  
Extreme Points ◽  
Fruit Fly ◽  
Optimization Process ◽  
Problem Solution ◽  
Fruit Fly Optimization Algorithm ◽  
Processing Application ◽  
Fruit Fly Optimization

AbstractBased on deeply analysis for optimization process of basic fruit fly optimization algorithm (FOA), a new improved FOA (IFOA) method is proposed, which modifies random search direction, increases the adjustment coefficient of search radius, and establishes a multi-sub-population solution mechanism. The proposed method can process the nonlinear objective function that has non-zero and non-negative extreme points. In the paper, IFOA method is applied to ill-conditioned problem solution in the field of surveying data processing. Application of the proposed method on two practical examples show that solution accuracy of IFOA is superior to that of three well-known intelligent optimization algorithms and two existing improved FOA methods, and it is also better than truncated singular value decomposition method and ridge estimation method. In addition, compared with intelligent search method represented by particle swarm optimization algorithm, The IFOA method has the advantages of less parameter settings, simple optimization process and easy program implementation. So, IFOA method is feasible, effective and practical in solving ill-conditioned problems.

The Application of Slip Joint Use in Space Frame Structure for Vehicle

2013 ◽  
Vol 423-426 ◽  
pp. 1944-1947
Author(s):  
Sheng Yun Lee ◽  
Ting Hao Cheng ◽  
Yu Ting Lin
Keyword(s):  
Dimensional Accuracy ◽  
Element Model ◽  
Frame Structure ◽  
Poor Control ◽  
Space Frame ◽  
Space Frames ◽  
The Common ◽  
The Finite Element Model ◽  
Joint Method ◽  
Space Frame Structure

The purpose of this paper is to analysis the finite element model of joint methods for chassis space frames of vehicles. Common tee-joint often have poor control of dimensional accuracy. The analysis includes the common tee-joint and new joint method. Although the new joint method will increase in weight a little and easily adjust the accuracy of space frame, it will also improve the connection strength.

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