Decomposition-Based Assembly Synthesis of a 3D Body-in-White Model for Structural Stiffness

2003 ◽  
Author(s):  
Naesung Lyu ◽  
Kazuhiro Saitou
Keyword(s):  
Pareto Front ◽  
Element Model ◽  
Vehicle Body ◽  
Structural Stiffness ◽  
Multi Objective Genetic Algorithm ◽  
First Case ◽  
Trade Offs ◽  
Body In White ◽  
Minimum Distortion

This paper presents an extension of our previous work on decomposition-based assembly synthesis for structural stiffness [1], where the 3D finite element model of a vehicle body-in-white (BIW) is optimally decomposed into a set of components considering the stiffness of the assembled structure under given loading conditions, as well as the manufacturability and assembleability or components. Two case studies, each focusing on the decomposition of a different portion of a BIW, are discussed. In the first case study, the side frame is decomposed for the minimum distortion of front door frame geometry under global bending. In the second case study, the side/floor frame and floor panels are decomposed for the minimum floor deflections under global bending. In each case study, multi-objective genetic algorithm [2,3] with graph-based crossover [4,5], combined with FEM analyses, is used to obtain Pareto optimal solutions. Representative designs are selected from the Pareto front and trade-offs among stiffness, manufacturability, and assembleability are discussed.

Decomposition-Based Assembly Synthesis of a Three-Dimensional Body-in-White Model for Structural Stiffness

2005 ◽  
Vol 127 (1) ◽  
pp. 34-48 ◽  
Author(s):  
Naesung Lyu ◽  
Kazuhiro Saitou
Keyword(s):  
Finite Element ◽  
Three Dimensional ◽  
Element Model ◽  
Vehicle Body ◽  
Structural Stiffness ◽  
First Case ◽  
Trade Offs ◽  
Body In White ◽  
Three Dimensional Finite Element

This paper presents an extension of our previous work on decomposition-based assembly synthesis for structural stiffness, where the three-dimensional finite element model of a vehicle body-in-white (BIW) is optimally decomposed into a set of components considering (1) stiffness of the assembled structure under given loading conditions, (2) manufacturability, and (3) assembleability of components. Two case studies, each focusing on the decomposition of a different portion of a BIW, are discussed. In the first case study, the side frame is decomposed for the minimum distortion of front door frame geometry under global bending. In the second case study, the side/floor frame and floor panels are decomposed for the minimum floor deflections under global bending. In each case study, multiobjective genetic algorithm with graph-based crossover, combined with finite element methods analyses, is used to obtain Pareto optimal solutions. Representative designs are selected from the Pareto front and trade-offs among stiffness, manufacturability, and assembleability are discussed.

Decomposition-Based Assembly Synthesis for Structural Stiffness

2003 ◽  
Vol 125 (3) ◽  
pp. 452-463 ◽  
Author(s):  
Naesung Lyu ◽  
Kazuhiro Saitou
Keyword(s):  
Joint Stiffness ◽  
Structural Stiffness ◽  
Body Frame ◽  
Passenger Car ◽  
Weld Joints ◽  
First Case ◽  
Design Variables ◽  
Door Panel ◽  
Minimum Distortion

This paper presents a method that systematically decomposes product geometry into a set of components considering the structural stiffness of the end product. A structure is represented as a graph of its topology, and the optimal decomposition is obtained by combining FEM analyses with a Genetic Algorithm. As the first case study, the side frame of a passenger car is decomposed for the minimum distortion of the front door panel geometry. As the second case study, the under body frame of a passenger car is decomposed for the minimum frame distortion. In both case studies, spot-weld joints are considered as joining methods, where each joint, which may contain multiple weld spots, is modeled as a torsional spring. First, the rates of the torsional springs are treated as constant values obtained in the literature. Second, they are treated as design variables within realistic bounds. By allowing the change in the joint rates, it is demonstrated that the optimal decomposition can achieve the smaller distortion with less amount of joint stiffness (hence less welding spots), than the optimal decomposition with the typical joint rates available in the literature.

Topology Optimization of Multi-Component Structures via Decomposition-Based Assembly Synthesis

2003 ◽  
Author(s):  
Naesung Lyu ◽  
Kazuhiro Saitou
Keyword(s):  
Genetic Algorithm ◽  
Pareto Front ◽  
Structural Performance ◽  
Pareto Optimal ◽  
Pareto Optimal Solutions ◽  
Structural Stiffness ◽  
Optimal Solutions ◽  
Ground Structure ◽  
Multi Objective Genetic Algorithm ◽  
Trade Offs

A method is presented for synthesizing multi-component structural assemblies with maximum structural performance and manufacturability. The problem is posed as a relaxation of decomposition-based assembly synthesis [1,2,3], where both topology and decomposition of a structure are regarded as variables over a ground structure with non-overlapping beams. A multi-objective genetic algorithm [4,5] with graph-based crossover [6,7,8], coupled with FEM analyses, is used to obtain Pareto optimal solutions to this problem, exhibiting trade-offs among structural stiffness, total weight, component manufacturability (size and simplicity), and the number of joints. Case studies with a cantilever and a simplified automotive floor frame are presented, and representative designs in the Pareto front are examined for the trade-offs among the multiple criteria.

Decomposition-Based Assembly Synthesis Based on Structural Stiffness Considerations

2002 ◽  
Author(s):  
Naesung Lyu ◽  
Kazuhiro Saitou
Keyword(s):  
Genetic Algorithm ◽  
Welded Joints ◽  
Joint Stiffness ◽  
Structural Stiffness ◽  
Passenger Car ◽  
Front Door ◽  
Design Variables ◽  
Door Panel ◽  
Minimum Distortion

This paper presents a method for systematically decomposes product geometry into a set of components considering the structural stiffness of the end product. A structure is represented a graph of its topology, and the optimal decomposition is obtained by combining FEM analyses with a Genetic Algorithm. As a case study, the side frame of a passenger car is decomposed for the minimum distortion of the front door panel geometry, where spot-welded joints are modeled as torsional springs. First, the rates of the torsional springs are treated as constant values obtained in the literature. Second, they are treated as design variables within realistic bounds. By allowing the change in the joint rates, it is demonstrated that the optimal decomposition can achieve the smaller distortion with less amount of joint stiffness (hence less welding spots), than the optimal decomposition with the typical joint rates available in the literature.

Decomposition-Based Assembly Synthesis for Structural Stiffness and Dimensional Integrity

2004 ◽  
Author(s):  
Naesung Lyu ◽  
Byungwoo Lee ◽  
Kazuhiro Saitou
Keyword(s):  
Cross Sections ◽  
Optimization Problem ◽  
Vehicle Body ◽  
Structural Stiffness ◽  
Passenger Vehicle ◽  
Unified Framework ◽  
Critical Dimensions ◽  
Multi Objective Genetic Algorithm ◽  
The Given

A method for optimally synthesizing multi-component structural assemblies of an aluminum space frame (ASF) vehicle body is presented, which simultaneously considers structural stiffness, manufacturing and assembly cost and dimensional integrity under a unified framework based on joint libraries. The optimization problem is posed as a simultaneous determination of the location and feasible types of joints in a structure selected from the predefined joint libraries, combined with the size optimization for the cross sections of the joined structural frames. The structural stiffness is evaluated by finite element analyses of a beam-spring model modeling the joints and joined frames. Manufacturing and assembly costs are estimated based on the geometries of the components and joints. Dimensional integrity is evaluated as the adjustability of the assembly for the given critical dimensions. The optimization problem is solved by a multi-objective genetic algorithm. An example on an ASF of the mid-size passenger vehicle is presented, where the representative designs in the Pareto set are examined with respect to the three design objectives.

The Concept modeling method: An approach to optimize the structural dynamics of a vehicle body

2020 ◽  
Vol 234 (13) ◽  
pp. 2923-2932 ◽  
Author(s):  
Mohammad Fard ◽  
Jianchun Yao ◽  
Richard Taube ◽  
John Laurence Davy
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Structural Dynamics ◽  
Element Model ◽  
Modeling Method ◽  
The Body ◽  
Vehicle Body ◽  
Concept Model ◽  
Body In White ◽  
Concept Modeling

Although the concept modeling method has already been proposed in the literature, there is still very limited knowledge about the validation and the application of this method for vehicle body design. This paper substantially increases this limited knowledge by developing a concept model for predicting and optimizing the structural dynamics of a vehicle body-in-white and validating this concept model against a detailed finite element model. The geometry and parameters of the concept model are extracted from its detailed finite element model. The major members and panels of the detailed finite element model are replaced by their equivalent beam and shell elements models. The joints of the concept model are represented by stiffness and mass matrices extracted from the detailed finite element model using the Guyan Reduction Method. The developed concept model is validated by comparing its structural dynamics, including the resonant frequencies and the vibration mode shapes, with the original detailed finite element model and the experimental results. The simplicity and small size of the concept model enable it to easily enhance the structural dynamics of the body-in-white by optimizing the cross-sections of the load-carrying members of the structure. The optimization in this case increased the resonant frequencies of the body-in-white while reducing the total mass by about 6 kg. The results prove that the concept modeling method can significantly enhance the body-in-white structural dynamics by reducing the complexity of the model and allowing the focus for the optimization to be on the main members of the structure at the development stage when the final design parameters are not well known and have not been fixed.

Escaping the Illegitimacy Net

2019 ◽  
pp. 104-126
Author(s):  
Sivan Shlomo Agon
Keyword(s):  
World Trade ◽  
Dispute Settlement ◽  
Goal Achievement ◽  
Appellate Body ◽  
First Case ◽  
Trade Offs ◽  
The World ◽  
The Face ◽  
Dispute Settlement System

This chapter engages in an in-depth, legal-empirical analysis of the landmark US-Shrimp dispute, the first case study examined under the category of trade-and disputes. The chapter begins with a short overview of the disputed measure at issue in US-Shrimp. It then discusses the infamous panel ruling rendered in the case and the intense legitimacy challenges the ruling ignited against the backdrop of the mounting criticism levelled at the World Trade Organization (WTO) in the late 1990s. On these foundations, the chapter turns to a comprehensive goal-based reading of the judicial endeavours carried out by the Appellate Body in US-Shrimp along the procedural, substantive, and rhetorical dimensions while tracing the goal shifts and trade-offs struck in the face of the enhanced legitimacy pressures the WTO and its Dispute Settlement System (DSS) confronted in this case. The chapter concludes by tying the goal-achievement patterns identified to the broader DSS goal-based effectiveness framework developed in the book.

Scales and Units

2018 ◽  
Author(s):  
Kathryn M. de Luna
Keyword(s):  
Language Change ◽  
Historical Linguistics ◽  
Bantu Languages ◽  
The North ◽  
First Case ◽  
Linguistic Evidence ◽  
River Region ◽  
History Of ◽  
Alternative Approaches

This chapter uses two case studies to explore how historians study language movement and change through comparative historical linguistics. The first case study stands as a short chapter in the larger history of the expansion of Bantu languages across eastern, central, and southern Africa. It focuses on the expansion of proto-Kafue, ca. 950–1250, from a linguistic homeland in the middle Kafue River region to lands beyond the Lukanga swamps to the north and the Zambezi River to the south. This expansion was made possible by a dramatic reconfiguration of ties of kinship. The second case study explores linguistic evidence for ridicule along the Lozi-Botatwe frontier in the mid- to late 19th century. Significantly, the units and scales of language movement and change in precolonial periods rendered visible through comparative historical linguistics bring to our attention alternative approaches to language change and movement in contemporary Africa.

Applications of random graphs

2017 ◽  
Author(s):  
A.C.C. Coolen ◽  
A. Annibale ◽  
E.S. Roberts
Keyword(s):  
Social Networks ◽  
Random Graphs ◽  
Interaction Network ◽  
Power Grids ◽  
Protein Protein Interaction ◽  
Topological Features ◽  
First Case ◽  
The Stability ◽  
Protein Protein Interaction Network

This chapter reviews graph generation techniques in the context of applications. The first case study is power grids, where proposed strategies to prevent blackouts have been tested on tailored random graphs. The second case study is in social networks. Applications of random graphs to social networks are extremely wide ranging – the particular aspect looked at here is modelling the spread of disease on a social network – and how a particular construction based on projecting from a bipartite graph successfully captures some of the clustering observed in real social networks. The third case study is on null models of food webs, discussing the specific constraints relevant to this application, and the topological features which may contribute to the stability of an ecosystem. The final case study is taken from molecular biology, discussing the importance of unbiased graph sampling when considering if motifs are over-represented in a protein–protein interaction network.

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