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.

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 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.

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.

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.

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.

scholarly journals Publishing at any cost: a cross-sectional study of the amount that medical researchers spend on open access publishing each year

BMJ Open ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. e047107
Author(s):  
Mallory K. Ellingson ◽  
Xiaoting Shi ◽  
Joshua J. Skydel ◽  
Kate Nyhan ◽  
Richard Lehman ◽  
...  
Keyword(s):  
Open Access ◽  
Senior Author ◽  
High Impact ◽  
Open Access Publishing ◽  
Original Research ◽  
Potential Cost ◽  
Cross Sectional ◽  
Review Articles ◽  
Open Access Journals ◽  
Medical Researchers

ObjectiveTo estimate the financial costs paid by individual medical researchers from meeting the article processing charges (APCs) levied by open access journals in 2019.DesignCross-sectional analysis.Data sourcesScopus was used to generate two random samples of researchers, the first with a senior author article indexed in the ‘Medicine’ subject area (general researchers) and the second with an article published in the ten highest-impact factor general clinical medicine journals (high-impact researchers) in 2019. For each researcher, Scopus was used to identify all first and senior author original research or review articles published in 2019. Data were obtained from Scopus, institutional profiles, Journal Citation Reports, publisher databases, the Directory of Open Access Journals, and individual journal websites.Main outcome measuresMedian APCs paid by general and high-impact researchers for all first and senior author research and review articles published in 2019.ResultsThere were 241 general and 246 high-impact researchers identified as eligible for our study. In 2019, the general and high-impact researchers published a total of 914 (median 2, IQR 1–5) and 1471 (4, 2–8) first or senior author research or review articles, respectively. 42% (384/914) of the articles from the general researchers and 29% (428/1471) of the articles from the high-impact medical researchers were published in fully open access journals. The median total APCs paid by general researchers in 2019 was US$191 (US$0–US$2500) and the median total paid by high-impact researchers was US$2900 (US$0–US$5465); the maximum paid by a single researcher in total APCs was US$30115 and US$34676, respectively.ConclusionsMedical researchers in 2019 were found to have paid between US$0 and US$34676 in total APCs. As journals with APCs become more common, it is important to continue to evaluate the potential cost to researchers, especially on individuals who may not have the funding or institutional resources to cover these costs.

Investigation on the free vibration behavior of sandwich conical shells with reinforced cores

2021 ◽  
pp. 109963622110204
Author(s):  
Mehdi Zarei ◽  
Gholamhossien Rahimi ◽  
Davoud Shahgholian-Ghahfarokhi
Keyword(s):  
Free Vibration ◽  
Orientation Angle ◽  
Element Model ◽  
Filament Winding ◽  
Vertex Angle ◽  
Sandwich Shell ◽  
Cross Sectional ◽  
Conical Shells ◽  
Vibration Behavior ◽  
Axial Forces

The free vibration behavior of sandwich conical shells with reinforced cores is investigated in the present study using experimental, analytical, and numerical methods. A new effective smeared method is employed to superimpose the stiffness contribution of skins with those of the stiffener in order to achieve equivalent stiffness of the whole structure. The stiffeners are also considered as a beam to support shear forces and bending moments in addition to the axial forces. Using Donnell’s shell theory and Galerkin method, the natural frequencies of the sandwich shell are subsequently derived. To validate analytical results, experimental modal analysis (EMA) is further conducted on the conical sandwich shell. For this purpose, a method is designed for manufacturing specimens through the filament winding process. For more validation, a finite element model (FEM) is built. The results revealed that all the validations were in good agreement with each other. Based on these analyses, the influence of the cross-sectional area of the stiffeners, the semi-vertex angle of the cone, stiffener orientation angle, and the number of stiffeners are investigated as well. The results achieved are novel and can be thus employed as a benchmark for further studies.

scholarly journals Scientific output of Brazilian dermatologists during the last 25 years in the five highest impact factor journals in dermatology

2012 ◽  
Vol 87 (5) ◽  
pp. 714-716
Author(s):  
Mariane Da Cas de Aquim Martins ◽  
Marília Gabriela Linné Netto Carneiro ◽  
Joyce Benck Utzig ◽  
Eleolina Lara Kaled Neta ◽  
Majenna Andrade Pachnicki ◽  
...  
Keyword(s):  
Impact Factor ◽  
Scientific Output ◽  
High Impact ◽  
Pemphigus Foliaceus ◽  
High Impact Factor ◽  
Controlled Clinical Trials ◽  
Cross Sectional ◽  
Qualitative And Quantitative ◽  
Area Of Interest ◽  
Number Of Publications

BACKGROUND: The qualitative and quantitative scientific output of Brazilian dermatologists in journals of high impact factor is little known. OBJECTIVE: To describe the scientific output of dermatologists from Brazilian institutions in journals of high impact factor. METHODS: The five journals with the highest impact factor in dermatology were analyzed. All articles produced from Brazilian institutions between 1986 and 2010 were compiled and the following aspects were analyzed: position of Brazilian researchers in the list of authors, selected theme, experimental design, studied disease, area of interest and year of publication. RESULTS: Seventy-four articles written with the participation of Brazilian dermatologists have been identified. Upon grouping the articles in five-year periods, an important increase was observed in the Brazilian production from the year 2006 onwards. The dermatologists were placed as second authors in the majority of cases (53.66%). According to the selected theme to be studied, the majority of the articles had a laboratory focus (45.95%). The majority of the articles reported cross-sectional studies or non-controlled clinical trials (both at 17.57%), and pemphigus foliaceus was the most studied disease (29.73%). CONCLUSION: The increase in the number of publications by Brazilian dermatologists over the last years is encouraging, but it is still small in comparison to the total number of articles published in these five periodicals.

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