scholarly journals RE-DESIGN OF A MOTORCYCLE HELMET FOR USE IN URBAN TRAFFIC: CONCEPTUAL DESIGN AND TESTING

2021 ◽  
Vol 1 ◽  
pp. 2531-2540
Author(s):  
Joanna Papadopoulou ◽  
Vassilis Papakostopoulos ◽  
Vassilis C. Moulianitis
Keyword(s):  
Urban Traffic ◽  
Von Mises Stress ◽  
Two Phase ◽  
Design Concepts ◽  
Motorcycle Helmet ◽  
Maximum Protection ◽  
Von Mises ◽  
Full Face ◽  
Phase Evaluation ◽  
Design And Testing

AbstractThis paper presents the re-design approach of an urban motorcycle helmet to prevent users bypassing the strap fastening system. Related studies show that although a full-face helmet provides the maximum protection to a rider, in practice, full-face helmeted riders in urban traffic tend to improperly fasten it. On that notion, the design goal was to conceive a helmet that combines the advantages of different helmet types while responding to urban driving needs. During design ideation possible solutions were examined focusing on different ways of accessing and fixating the helmet on a rider’s head, without using a strap fastening system. Preliminary concept development produced three design concepts, that were evaluated using two sets of prototypes: (a) the 3D printing method under a 1:2 scale was used to detect any design faults, while the 3D modeled concepts were evaluated in four different crash impacts regarding total deformation and von-Mises stress, and (b) 1:1 models of the three concepts were used by experienced riders to assess possible usability issues during helmet placement/removal. Results of the two-phase evaluation of the three concepts and design issues for further development of them are discussed.

GA Wavelet Transform Direction for γ-Phase Shaped Finite Element Analysis

2013 ◽  
Vol 791-793 ◽  
pp. 573-576
Author(s):  
Lei Meng
Keyword(s):  
Finite Element ◽  
Single Crystal ◽  
Phase Distribution ◽  
Tensile Creep ◽  
Von Mises Stress ◽  
Initial Population ◽  
Two Phase ◽  
Element Analysis ◽  
Multimodal Function ◽  
Von Mises

1040 °C was studied during the period imposed 137MPa tensile creep nickel-base single crystal superalloys γ/γ the evolution of two-phase approach. ANSYS finite element method is using a single crystal alloy with / without external load when the Von Mises stress in the gand γ two phase distribution. The comprehensive analysis of the formula, the coefficient values usually experience, not very accurate, this article dealing with GA coefficient. This algorithm uses orthogonal crossover to generate initial population and uses elitist-crossover to increase the good patterns of the population and uses hybrid mutation to increase the ability of local and global optimization. It has shown fascinating results when being used in the optimization of multimodal function. The results showed that: In the creep period, the corresponding cubic γ along the von Mises stress and strain energy density of the crystal face to form raft-like organizations.

Finite Element Simulation of Tensile Behaviors in the Elastic Region for PP/Nano-TiO2 Composites

2010 ◽  
Vol 150-151 ◽  
pp. 1819-1823
Author(s):  
Yu Jiao Wu ◽  
Ming Rui Gao ◽  
Yu Ling Chen ◽  
Juan Li ◽  
Shao Lin Ju
Keyword(s):  
Finite Element ◽  
Stress Field ◽  
Volume Fraction ◽  
Local Stress ◽  
Von Mises Stress ◽  
Analysis Model ◽  
Nano Tio2 ◽  
Two Phase ◽  
Element Analysis ◽  
Von Mises

Polypropylene(PP)/nano-TiO2 composites were prepared by the melt intercalation molding. Based on the assumption of continuum mechanics model for materials, a finite element analysis model for the composites was constructed using ANSYS 11.0 software. In the stage of deformation (pre-yield regime) the response mechanism of the stress and the strain for composites was investigated, and the von mises stress field of PP/nano-TiO2 composites has also been simulated. It was found that the simulation results are Consistent with the testing results at low volume strain level. The results simulated using the 2D model are accurate with the experimental results. If the volume fraction of particles is less, other particles have little influence on the local stress field of a certain particle, no obvious overlap or cross of the stress field could be found between two neighboring particles. While applying different loads, the stress jumps to maximum stress value in the interaction region of the two phase firstly, and then it occurs that the particles debond with the matrix.

Fluid-Structure Interaction Analysis of Flow-Induced Deformation in a Two-Phase, Neo-Hookean Marine Egg

2006 ◽  
Vol 128 (4) ◽  
pp. 519-526 ◽  
Author(s):  
T. Kim ◽  
C W. Wang ◽  
F. I. M. Thomas ◽  
A. M. Sastry
Keyword(s):  
Interaction Analysis ◽  
Von Mises Stress ◽  
Finite Element Analyses ◽  
Two Phase ◽  
Shear Moduli ◽  
Arbacia Punctulata ◽  
Structure Interaction ◽  
Material Parameters ◽  
Von Mises ◽  
Von Mises Stresses

Coupled computational fluid dynamics and finite element analyses were used to determine the material properties of the egg and jelly layer of the sea urchin Arbacia punctulata. Prior experimental shear flow results were used to provide material parameters for these simulations. A Neo-Hookean model was used to model the hyperelastic behaviors of the jelly layer and egg. A simple compressive simulation was then performed, to compare the maximum von Mises stresses within eggs, with and without jelly layers. Results of this study showed that (1) shear moduli range from ∼100to160Pa, and ∼40to140Pa for an egg without a jelly layer, and jelly layer itself, respectively; and (2) the presence of the jelly layer significantly reduces maximum von Mises stress in an egg undergoing compression.

Based on Convolution Algorithm Single Crystal Finite Element Analysis

2012 ◽  
Vol 532-533 ◽  
pp. 1120-1123
Author(s):  
Shu Zhang ◽  
Lei Meng
Keyword(s):  
Finite Element ◽  
Single Crystal ◽  
Phase Distribution ◽  
Tensile Creep ◽  
Von Mises Stress ◽  
Initial Population ◽  
Two Phase ◽  
Convolution Algorithm ◽  
Multimodal Function ◽  
Von Mises

1040 °C was studied during the period imposed 137MPa tensile creep nickel-base single crystal superalloys γ/γ' the evolution of two-phase approach. ANSYS finite element method is using a single crystal alloy with / without external load when the Von Mises stress in the gand γ' two phase distribution. The comprehensive analysis of the formula, the coefficient values usually experience, not very accurate, this article dealing with convolution Algorithm coefficient. This algorithm uses orthogonal crossover to generate initial population and uses elitist-crossover to increase the good patterns of the population and uses hybrid mutation to increase the ability of local and global optimization. It has shown fascinating results when being used in the optimization of multimodal function. The results showed that: In the creep period, the corresponding cubic γ' along the von Mises stress and strain energy density of the crystal face to form raft-like organizations.

Conceptual Design of Structures Using an Upper Bound of von Mises Stress

2018 ◽  
Vol 19 (1) ◽  
Author(s):  
Ashok V. Kumar
Keyword(s):  
Topology Optimization ◽  
Stress Concentration ◽  
Upper Bound ◽  
Von Mises Stress ◽  
Optimization Approach ◽  
Objective Functions ◽  
Stress Concentrations ◽  
Handling Stress ◽  
Design Concepts ◽  
Von Mises

Optimal layouts for structural design have been generated using topology optimization approach with a wide variety of objectives and constraints. Minimization of compliance is the most common objective but the resultant structures often have stress concentrations. Two new objective functions, constructed using an upper bound of von Mises stress, are presented here for computing design concepts that avoid stress concentration. The first objective function can be used to minimize mass while ensuring that the design is conservative and avoids stress concentrations. The second objective can be used to tradeoff between maximizing stiffness versus minimizing the maximum stress to avoid stress concentration. The use of the upper bound of von Mises stress is shown to avoid singularity problems associated with stress-based topology optimization. A penalty approach is used for eliminating stress concentration and stress limit violations which ensures conservative designs while avoiding the need for special algorithms for handling stress localization. In this work, shape and topology are represented using a density function with the density interpolated piecewise over the elements to obtain a continuous density field. A few widely used examples are utilized to study these objective functions.

scholarly journals Structural Design Method for Constructions: Simulation, Manufacturing and Experiment

Materials ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6064
Author(s):  
Pavel Bolshakov ◽  
Nikita Kharin ◽  
Ramil Kashapov ◽  
Oskar Sachenkov
Keyword(s):  
Additive Manufacturing ◽  
Structural Design ◽  
Design Method ◽  
Manufacturing Technology ◽  
Von Mises Stress ◽  
Design Concepts ◽  
Additive Manufacturing Technology ◽  
Basic Cell ◽  
Complex Structural ◽  
Von Mises

The development of additive manufacturing technology leads to new concepts for design implants and prostheses. The necessity of such approaches is fueled by patient-oriented medicine. Such a concept involves a new way of understanding material and includes complex structural geometry, lattice constructions, and metamaterials. This leads to new design concepts. In the article, the structural design method is presented. The general approach is based on the separation of the micro- and macro-mechanical parameters. For this purpose, the investigated region as a complex of the basic cells was considered. Each basic cell can be described by a parameters vector. An initializing vector was introduced to control the changes in the parameters vector. Changing the parameters vector according to the stress-strain state and the initializing vector leads to changes in the basic cells and consequently to changes in the microarchitecture. A medium with a spheroidal pore was considered as a basic cell. Porosity and ellipticity were used for the parameters vector. The initializing vector was initialized and depended on maximum von Mises stress. A sample was designed according to the proposed method. Then, solid and structurally designed samples were produced by additive manufacturing technology. The samples were scanned by computer tomography and then tested by structural loads. The results and analyses were presented.

Effects of occlusal scheme on All-on-Four abutments, screws and prostheses: A three-dimensional finite element study

2020 ◽  
Author(s):  
Nurullah Türker ◽  
Hümeyra Tercanlı Alkış ◽  
Steven J Sadowsky ◽  
Ulviye Şebnem Büyükkaplan
Keyword(s):  
Finite Element ◽  
Three Dimensional ◽  
Good Prognosis ◽  
Von Mises Stress ◽  
Element Analysis ◽  
Group Function ◽  
Occlusal Contact ◽  
Maximum Deformation ◽  
Contact Points ◽  
Von Mises

An ideal occlusal scheme plays an important role in a good prognosis of All-on-Four applications, as it does for other implant therapies, due to the potential impact of occlusal loads on implant prosthetic components. The aim of the present three-dimensional (3D) finite element analysis (FEA) study was to investigate the stresses on abutments, screws and prostheses that are generated by occlusal loads via different occlusal schemes in the All-on-Four concept. Three-dimensional models of the maxilla, mandible, implants, implant substructures and prostheses were designed according to the All-on-Four concept. Forces were applied from the occlusal contact points formed in maximum intercuspation and eccentric movements in canine guidance occlusion (CGO), group function occlusion (GFO) and lingualized occlusion (LO). The von Mises stress values for abutment and screws and deformation values for prostheses were obtained and results were evaluated comparatively. It was observed that the stresses on screws and abutments were more evenly distributed in GFO. Maximum deformation values for prosthesis were observed in the CFO model for lateral movement both in the maxilla and mandible. Within the limits of the present study, GFO may be suggested to reduce stresses on screws, abutments and prostheses in the All-on-Four concept.

The Influence of Loading Position in A Priori High Stress Detection using Mode Superposition

2020 ◽  
Vol 1 (1) ◽  
pp. 93-102
Author(s):  
Carsten Strzalka ◽  
◽  
Manfred Zehn ◽  
Keyword(s):  
Finite Element ◽  
Degrees Of Freedom ◽  
Equations Of Motion ◽  
A Priori ◽  
High Stress ◽  
Von Mises Stress ◽  
Detailed Knowledge ◽  
Variable Loading ◽  
Numerical Effort ◽  
Von Mises

For the analysis of structural components, the finite element method (FEM) has become the most widely applied tool for numerical stress- and subsequent durability analyses. In industrial application advanced FE-models result in high numbers of degrees of freedom, making dynamic analyses time-consuming and expensive. As detailed finite element models are necessary for accurate stress results, the resulting data and connected numerical effort from dynamic stress analysis can be high. For the reduction of that effort, sophisticated methods have been developed to limit numerical calculations and processing of data to only small fractions of the global model. Therefore, detailed knowledge of the position of a component’s highly stressed areas is of great advantage for any present or subsequent analysis steps. In this paper an efficient method for the a priori detection of highly stressed areas of force-excited components is presented, based on modal stress superposition. As the component’s dynamic response and corresponding stress is always a function of its excitation, special attention is paid to the influence of the loading position. Based on the frequency domain solution of the modally decoupled equations of motion, a coefficient for a priori weighted superposition of modal von Mises stress fields is developed and validated on a simply supported cantilever beam structure with variable loading positions. The proposed approach is then applied to a simplified industrial model of a twist beam rear axle.

scholarly journals Numerical Investigation of the Deformable Porous Media Treated by the Intermittent Microwave

Processes ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 757
Author(s):  
Tianyi Su ◽  
Wenqing Zhang ◽  
Zhijun Zhang ◽  
Xiaowei Wang ◽  
Shiwei Zhang
Keyword(s):  
Porous Media ◽  
Heat Transport ◽  
Liquid Water ◽  
Von Mises Stress ◽  
Temperature Deformation ◽  
Local Maxima ◽  
Whole Process ◽  
Surface Areas ◽  
Pulse Ratio ◽  
Von Mises

A 2D axi-symmetric theoretical model of dielectric porous media in intermittent microwave (IMW) thermal process was developed, and the electromagnetic energy, multiphase transport, phase change, large deformation, and glass transition were taken into consideration. From the simulation results, the mass was mainly carried by the liquid water, and the heat was mainly carried by liquid water and solid. The diffusion was the dominant mechanism of the mass transport during the whole process, whereas for the heat transport, the convection dominated the heat transport near the surface areas during the heating stage. The von Mises stress reached local maxima at different locations at different stages, and all were lower than the fracture stress. A material treated by a longer intermittent cycle length with the same pulse ratio (PR) tended to trigger the phenomena of overheat and fracture due to the more intense fluctuation of moisture content, temperature, deformation, and von Mises stress. The model can be extended to simulate the intermittent radio frequency (IRF) process on the basis of which one can select a suitable energy source for a specific process.

scholarly journals Three-Dimensional Analysis of the In Vivo Motion of Implantable Cardioverter Defibrillator Leads

2021 ◽  
Author(s):  
Tamas Szili-Torok ◽  
Jens Rump ◽  
Torsten Luther ◽  
Sing-Chien Yap
Keyword(s):  
Three Dimensional ◽  
Second Phase ◽  
Two Phase ◽  
Maximum Curvature ◽  
Phase Study ◽  
Absolute Curvature ◽  
Icd Leads ◽  
Lead Testing ◽  
Design And Testing

Abstract Better understanding of the lead curvature, movement and their spatial distribution may be beneficial in developing lead testing methods, guiding implantations and improving life expectancy of implanted leads. Objective The aim of this two-phase study was to develop and test a novel biplane cine-fluoroscopy-based method to evaluate input parameters for bending stress in leads based on their in vivo 3D motion using precisely determined spatial distributions of lead curvatures. Potential tensile, compressive or torque forces were not subjects of this study. Methods A method to measure lead curvature and curvature evolution was initially tested in a phantom study. In the second phase using this model 51 patients with implanted ICD leads were included. A biplane cine-fluoroscopy recording of the intracardiac region of the lead was performed. The lead centerline and its motion were reconstructed in 3D and used to define lead curvature and curvature changes. The maximum absolute curvature Cmax during a cardiac cycle, the maximum curvature amplitude Camp and the maximum curvature Cmax@amp at the location of Camp were calculated. These parameters can be used to characterize fatigue stress in a lead under cyclical bending. Results The medians of Camp and Cmax@amp were 0.18 cm−1 and 0.42 cm−1, respectively. The median location of Cmax was in the atrium whereas the median location of Camp occurred close to where the transit through the tricuspid valve can be assumed. Increased curvatures were found for higher slack grades. Conclusion Our results suggest that reconstruction of 3D ICD lead motion is feasible using biplane cine-fluoroscopy. Lead curvatures can be computed with high accuracy and the results can be implemented to improve lead design and testing.

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