A Case Study of the Influence on Crashworthiness From the Implementation of Ice Strengthening

2014 ◽  
Author(s):  
Halvor Larsson Aga ◽  
Bernt Johan Leira ◽  
Sören Ehlers ◽  
Hans Arne Blomvågnes-Bakke
Keyword(s):  
Minimum Distance ◽  
State Of The Art ◽  
Nonlinear Finite Element ◽  
Element Analysis ◽  
Outer Skin ◽  
Collision Safety ◽  
Fuel Tanks ◽  
Ship Collision ◽  
Lng Fuel

This paper presents a study of the influence from ice strengthening on the crashworthiness with regards to placement of LNG fuel tanks. First a brief introduction to the ship collision research as well as an assessment of the state of the art regarding nonlinear finite element analysis for use in ship collision analysis are given. Secondly the implications from the introduction of LNG fuel tanks on ships in context of collision safety are discussed. Thirdly how to quantify and compare energy absorption for different ship designs is discussed. This is followed by the presentation of a study regarding the horizontal placement of LNG fuel tanks. The study starts with presenting the variables chosen and the models made for the analysis. Energy versus indentation curves are presented for three different designs, where a standard cargo carrier is compared with two different design solutions where the cargo carrier is equipped with either vertical or longitudinal ice strengthening. It is concluded that in this case the benefit in terms of reduction of the minimum distance from the outer skin to the LNG fuel tank, as given in the current rules, is around 39%.

A Technique to Characterize Rate-Dependent Failure Envelopes in Surface Mount Assemblies

2006 ◽  
Author(s):  
J. Varghese ◽  
A. Dasgupta
Keyword(s):  
Finite Element Analysis ◽  
Failure Strain ◽  
Nonlinear Finite Element ◽  
Element Analysis ◽  
Rate Dependent ◽  
Strain And Strain Rate ◽  
Failure Envelopes ◽  
Dependent Failure ◽  
Printed Wiring Assemblies

This paper characterizes the fatigue failure envelopes for solder damage in Printed Wiring Assemblies (PWAs) subjected to dynamic loading. An empirical, rate-dependent, power-law durability model, motivated by mechanistic considerations, is used to characterize the failure envelopes in terms of PWA flexural strain and strain rate. Explicit nonlinear finite element analysis (FEA) is used to make the damage constants independent of the specimen geometry and characterize the durability in terms of the ratio of solder plastic strain to its failure strain. A case study, using a simple PWA specimen containing a single area array component, is presented to demonstrate the proposed approach.

Nonlinear Variation Analysis of Compliant Sheet Metal Assemblies Including Effect of Surface Continuity in Components

2014 ◽  
Vol 532 ◽  
pp. 503-509 ◽  
Author(s):  
Seyed Ali Hashemian ◽  
Behnam Moetakef Imani
Keyword(s):  
Sheet Metal ◽  
Free Probability ◽  
Nonlinear Finite Element ◽  
Variation Analysis ◽  
Element Analysis ◽  
Nonlinear Variation ◽  
Final Assembly ◽  
Highly Nonlinear ◽  
Effect Of Surface

Assembly processes are often complex and highly nonlinear. In sheet metal assemblies, the most important factor that makes the process nonlinear is the contact interaction between mating parts during the assembly process. This paper focuses on developing a methodology for nonlinear variation analysis of compliant sheet metal assemblies which also includes the effect of surface continuity of components. The proposed methodology integrates a nonlinear finite element analysis with an improved sensitivity-free probability analysis in order to predict the final assembly variation. The efficiency of the developed approach is evaluated by an experimental case study as well as Monte Carlo simulation.

Multiple Surrogate-Assisted Many-Objective Optimization for Computationally Expensive Engineering Design

2018 ◽  
Vol 140 (5) ◽  
Author(s):  
Kalyan Shankar Bhattacharjee ◽  
Hemant Kumar Singh ◽  
Tapabrata Ray
Keyword(s):  
Engineering Design ◽  
Optimization Problems ◽  
State Of The Art ◽  
Performance Criteria ◽  
Vehicle Design ◽  
Multi Objective Optimization ◽  
Element Analysis ◽  
Research Gap ◽  
Computationally Expensive

Engineering design often involves problems with multiple conflicting performance criteria, commonly referred to as multi-objective optimization problems (MOP). MOPs are known to be particularly challenging if the number of objectives is more than three. This has motivated recent attempts to solve MOPs with more than three objectives, which are now more specifically referred to as “many-objective” optimization problems (MaOPs). Evolutionary algorithms (EAs) used to solve such problems require numerous design evaluations prior to convergence. This is not practical for engineering applications involving computationally expensive evaluations such as computational fluid dynamics and finite element analysis. While the use of surrogates has been commonly studied for single-objective optimization, there is scarce literature on its use for MOPs/MaOPs. This paper attempts to bridge this research gap by introducing a surrogate-assisted optimization algorithm for solving MOP/MaOP within a limited computing budget. The algorithm relies on principles of decomposition and adaptation of reference vectors for effective search. The flexibility of function representation is offered through the use of multiple types of surrogate models. Furthermore, to efficiently deal with constrained MaOPs, marginally infeasible solutions are promoted during initial phases of the search. The performance of the proposed algorithm is benchmarked with the state-of-the-art approaches using a range of problems with up to ten objective problems. Thereafter, a case study involving vehicle design is presented to demonstrate the utility of the approach.

scholarly journals On the infinitely-stable rotational mechanism using the off-axis rotation of a bistable translational mechanism

2015 ◽  
Vol 6 (1) ◽  
pp. 75-80 ◽  
Author(s):  
G. Hao ◽  
J. Mullins
Keyword(s):  
Nonlinear Finite Element ◽  
Critical Transition ◽  
Element Analysis ◽  
Primary Motion ◽  
Prior Art ◽  
Transition Points ◽  
Axis Rotation ◽  
Translational Mechanisms ◽  
Rotation Behaviour

Abstract. Different from the prior art concentrating on the primary translation of bistable translational mechanisms this paper investigates the off-axis rotation behaviour of a bistable translational mechanism through displacing the guided primary translation at different positions. Moment-rotation curves obtained using the nonlinear finite element analysis (FEA) for a case study show the multiple stable positions of the rotation under each specific primary motion, suggesting that an infinitely-stable rotational mechanism can be achieved by controlling the primary motion. In addition, several critical transition points have been identified and qualitative testing has been conducted for the case study.

Centrality Measures

2018 ◽  
Author(s):  
Ginestra Bianconi
Keyword(s):  
State Of The Art ◽  
Centrality Measures ◽  
Eigenvector Centrality ◽  
Multilayer Networks ◽  
Comprehensive Description ◽  
Multilayer Network ◽  
Suitable Definition ◽  
Katz Centrality ◽  
Pagerank Centrality

Defining the centrality of nodes and layers in multilayer networks is of fundamental importance for a variety of applications from sociology to biology and finance. This chapter presents the state-of-the-art centrality measures able to characterize the centrality of nodes, the influences of layers or the centrality of replica nodes in multilayer and multiplex networks. These centrality measures include modifications of the eigenvector centrality, Katz centrality, PageRank centrality and Communicability to the multilayer network scenario. The chapter provides a comprehensive description of the research of the field and discusses the main advantages and limitations of the different definitions, allowing the readers that wish to apply these techniques to choose the most suitable definition for his or her case study.

scholarly journals Photovoltaics Enabling Sustainable Energy Communities: Technological Drivers and Emerging Markets

Energies ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1862
Author(s):  
Alexandros-Georgios Chronis ◽  
Foivos Palaiogiannis ◽  
Iasonas Kouveliotis-Lysikatos ◽  
Panos Kotsampopoulos ◽  
Nikos Hatziargyriou
Keyword(s):  
State Of The Art ◽  
Research Question ◽  
Economic Benefits ◽  
Energy Market ◽  
Small Scale ◽  
Local Energy ◽  
Community Members ◽  
Open Research ◽  
Energy Community

In this paper, we investigate the economic benefits of an energy community investing in small-scale photovoltaics (PVs) when local energy trading is operated amongst the community members. The motivation stems from the open research question on whether a community-operated local energy market can enhance the investment feasibility of behind-the-meter small-scale PVs installed by energy community members. Firstly, a review of the models, mechanisms and concepts required for framing the relevant concepts is conducted, while a clarification of nuances at important terms is attempted. Next, a tool for the investigation of the economic benefits of operating a local energy market in the context of an energy community is developed. We design the local energy market using state-of-the-art formulations, modified according to the requirements of the case study. The model is applied to an energy community that is currently under formation in a Greek municipality. From the various simulations that were conducted, a series of generalizable conclusions are extracted.

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