Spatial distribution and orientation of nanotubes for suppression of stress concentrations optimized using genetic algorithm and finite element analysis

2018 ◽  
Vol 158 ◽  
pp. 136-146 ◽  
Author(s):  
Qiang Liu ◽  
Stepan V. Lomov ◽  
Larissa Gorbatikh
1981 ◽  
Vol 18 (01) ◽  
pp. 51-68
Author(s):  
Donald Liu ◽  
Abram Bakker

Local structural problems in ships are generally the result of stress concentrations in structural details. The intent of this paper is to show that costly repairs and lay-up time of a vessel can often be prevented, if these problem areas are recognized and investigated in the design stages. Such investigations can be performed for minimal labor and computer costs by using finite-element analysis techniques. Practical procedures for analyzing structural details are presented, including discussions of the results and the analysis costs expended. It is shown that the application of the finite-element analysis technique can be economically employed in the investigation of structural details.


2014 ◽  
Vol 49 (9) ◽  
pp. 1057-1069 ◽  
Author(s):  
Baris Sabuncuoglu ◽  
Svetlana Orlova ◽  
Larissa Gorbatikh ◽  
Stepan V Lomov ◽  
Ignaas Verpoest

1994 ◽  
Vol 3 (5) ◽  
pp. 096369359400300
Author(s):  
M. Hadjiprocopiou ◽  
G.T. Reed ◽  
L. Hollaway ◽  
A.M. Thorne

Finite Element analysis is used to determine and to minimise the stress concentrations which arise in a “Smart” material system due to the embedded optical fibre sensors. The FE results show that with careful selection of the coating stiffness and thickness the stress concentrations caused by the fibre inclusion in the host material can be reduced.


Author(s):  
Jean Paul Kabche ◽  
Mauri´cio Rangel Pacheco ◽  
Ivan Thesi ◽  
Luiz Carlos Largura

Bolted connections are largely employed in various types of engineering structures to transfer loads from one member to another. In particular, the off-shore industry has made extensive use of these connections, predominantly at the sub-sea level. In spite of their advantages, bolted joints are critical regions and may become sources of structural weakness due to large stress concentrations. Under severe operating conditions, micro-cracks can develop in the bolt, creating regions of elevated stress which may significantly reduce the integrity of the connection and ultimately lead to failure. This paper presents the three-dimensional finite element analysis of a steel locked bolt assembly aimed to assess the effect of micro-cracks on the structural integrity of the assembly using the commercial finite element package ANSYS. Non-linear contact between the bolt and nut threads is considered, where frictional sliding between components is allowed. A bi-linear isotropic hardening model is used to account for non-linear material behavior. The assembly is loaded by applying a pre-load of fifty percent of the yield stress of the material, according to the API-6A Norm. Two geometric models are investigated: a healthy locked bolt assembly with no initial cracks; and a damaged model, where a circular crack is introduced at the root of the bolt threads. The effect of the crack size is studied by modeling the crack with three different radius sizes. The J-Integral fracture mechanics methodology was used to study the stress concentrations in the damaged model.


2015 ◽  
Vol 6 (6) ◽  
pp. 759-774
Author(s):  
André F. B. P. Pinto ◽  
S.M.O. Tavares ◽  
José M. A. César de Sá ◽  
P.M.S.T. de Castro

Purpose – The purpose of this paper is to use PAM-CRASH, a finite element analysis solver, to assess the performance of a mass production vehicle cross car beam (CCB) under an overlap frontal crash scenario (crashworthiness). Simulation results were reviewed according to what is plausible to register regarding some critical points displacements and, moreover, to identify its stress concentrations zones. Furthermore, it was also computed the CCB modal analysis (noise, vibration and harshness (NVH) assessment) in order to examine if its natural modes are within with the original equipment manufacturer (OEM) design targets. Design/methodology/approach – The available data at the beginning of the present study consisted of the structure CAD file and performance requirements stated by the OEM for NVH. No technical information was available concerning crashworthiness. Taking into account these limitations, it was decided to adapt the requirements for other mass production cars of the same category, as regards dynamic loading. A dynamic explicit code finite element analysis was performed throughout the CCB structure simulating the 120e−3 s crash event. For the modal analysis, there were some necessary modifications to the explicit finite element model in order to perform the analysis in implicit code. In addition, the car body in white stiffness was assigned at the boundaries. These stiffness values are withdrawn from the points where the CCB is attached to the car body’s sheet metal components. Findings – Although the unavailability of published results for this particular CCB model prevents a comparison of the present results, the trends and order of magnitude of the crash simulation results are within the expectations for this type of product. Concerning modal analysis, the steering column first natural frequency has a percent deviation from the design lower bound value of 5.09 percent when local body stiffness is considered and of 1.94 percent with fixed boundary conditions. The other requirement of the NVH assessment regarding a 5 Hz minimum interval between first vehicle CCB mode and the first mode of the steering column was indeed achieved with both boundary configurations. Originality/value – This study is a further confirmation of the interest of numerical modeling as a first step before actual experimental testing, saving time and money in an automotive industry that has seen an enormous increase of the demand for new car models in the last decade.


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