• Journal of Korean Society of Industrial and Systems Engineering
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• v.41 no.3
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• pp.115-119
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• 2018

Defining and measuring non-rigid or flexible parts has been controversial in industry for many years. There are two primary areas of controversy. The first is agreeing on what exactly a non-rigid part is. The second is agreeing on how to define and measure a non-rigid part. The subject of non-rigid parts is further complicated by the brief coverage it receives in the national and international standards. This leaves each company to improvise or create its own rules for non-rigid parts. There are some who believe that Geometrical Dimensioning and Tolerancing (GD&T) should not be used on non-rigid parts. This is not true. The ASME Y14.5M standard applies to rigid parts as a default condition. However, there is no definition given for a rigid part. The term rigid part has been used in industry for so long that it has gained a definition by its general use. When most people in industry say rigid part, they are referring to a part doesn't move (deform or flex) when a force (including gravity) is applied. How much force is relative based on the part characteristics. In reality, all parts will deform (or flex) if enough force is applied. Using this logic, all parts would be considered non-rigid. However, we all know that this is not how parts are treated in industry. Although GD&T defaults to rigid parts, it should also be used on non-rigid parts with a few special techniques. Actually 50~60% of all products designed contain parts or features on parts that are non-rigid. Therefore, we try to suggest the definitions of rigid and non-rigid parts and method to measure non-rigid parts.

• Structural Engineering and Mechanics
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• v.2 no.4
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• pp.327-343
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• 1994

This is the second part of the paper (Rojek and Kleiber 1993) devoted to nonlinear dynamic analysis of structures consisting of rigid and deformable parts. The first part contains a theoretical formulation of nonlinear equations of motion for the coupled system as well as a solution algorithm. The second part presents the computer implementation of the equations derived in the first part with a short review of the capabilities of the computer program used and the library of finite elements. Details of material nonlinearity treatment are also given. The paper is illustrated by discussing a practical problem of a safety cab analysis for an agricultural tractor.

• Journal of Biomedical Engineering Research
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• v.25 no.4
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• pp.277-282
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• 2004

In order to investigate the small female occupant behavior and accompanying injury mechanisms in vehicular trash event, a finite element model of $5^{th}$ percentile female has been developed. The model consists of articulated rigid body, which represents the morphology of small female body, and internal components with anatomical details. Articulated rigid body model serves as a basic platform for joining the detail internal skeletons and organs, while itself can be used for representing the overall kinematics of small female occupant. The modeling details such as anthropometry and finite element structure as well as validation results for the articulated rigid body model are introduced in this paper. The second part of the modeling, i.e. the internal components with anatomical details of small female are presented in subsequent part II of the paper.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.7
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• pp.119-128
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• 1998

In this paper, nonsteady state shaped drawing process has been investigated using the three-dimensional rigid-plastic finite element method. In order to analyze the shaped drawing process, a method to define straight converging die considering straight die part, die radius part and bearing part has been proposed. In addition, the modeling of initial billet and the generation procedure of mesh system have been suggested. The three-dimensional rigid-plastic finite element simulation has been performed for a square sectional drawing process and its result has been confirmed in comparison with the existing experimental one. Also, for the same process conditions, the effect of perimeter ratio in the shaped drawing process has been investigated.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.463-467
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• 2003

This part of ISO 1940 covers the following: a) identification of errors in the balancing process of rigid rotors: b) assessment of errors: c) guidelines for taking into account: d) the evaluation of residual unbalance in two correction planes. Detailed consideration of errors associated with the determination of residual unbalance is covered in the first part of ISO 1940.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.05a
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• pp.127-128
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• 2021

Rigid urethane foam is widely applied because it is light and has superior insulation performance compared to insulation materials such as EPS or glass wool. However, it has the disadvantage of being vulnerable to fire. Therefore, in this study, before proceeding with the research to improve the fire resistance of the rigid polyurethane foam, we would like to investigate the change in density and thermal conductivity of the rigid polyurethane foam according to the change in the mixed weight of the main material and the curing agent. It was found that the density increased as the mixed weight increased. The thermal conductivity showed similar values overall. As for the density distribution, the central part was low and the outer part was high.

• Journal of Korean Association for Spatial Structures
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• v.6 no.3 s.21
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• pp.87-92
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• 2006

This paper is a study on the experiment and elasto-plastic discrete limit analysis of reinforced concrete circular cylindrical shell by the rigid-bodies spring model. In the rigid bodies-spring model, each collapsed part or piece of structures at the limiting state of loading is assumed to behave like rigid bodies. The present author propose new discrete elements for elasto-plastic analysis of cylindrical shell structures, that is, a rectangular-shaped cylindrical element and a rhombus-shaped cylindrical element for the improvement and expansion of this rigid-bodies spring model. In this study, it is proposed how this rigid element-bodies spring model can be applied to the elasto-plastic discrete limit analysis of cylindrical shell structures. Some numerical results of elasto-plastic discrete limit analysis and experimental results such as the curve of load-displacement and the yielding and fracturing pattern of circular cylindrical shell under horizontal load are shown.

• Journal of Korean Association for Spatial Structures
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• v.1 no.2 s.2
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• pp.111-116
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• 2001

This paper is a study on the elasto-plastic analysis of reinforced concrete precast large panel connections by rigid element spring model. In the analysis of rigid element spring model, each collapsed part or piece of structures at limiting state of loading is assumed to behave like rigid bodies. The present author propose new elements for the improement and expansion of the rigid element spring model. In this study, it is proposed how the rigid element method can be applied to the elesto-plastic analysis of precat large panel connections. Some numerical results of analytical modeling and load displacement curves are shown.

• The Journal of Korea Robotics Society
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• v.12 no.3
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• pp.263-269
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• 2017

Recently, soft robots using soft materials are presented. Thanks to soft materials, soft robots have flexible, highly-stretchable or adaptable features. However, due to the flexibility of soft material, it is hard for soft robots to control accurately or perform high force. To deal with these limitations, variable stiffness technology, which enables the stiffness control of structure, has been developed. In this research, a dual-stiffness structure that is actuated by the assembly of two flexible structures are presented. Each flexible structure consists of flexible film part and rigid parts placed at regular intervals. The flexibility of film between rigid parts allows each structure to move softly. On the other hand, by combining two structures rigid part of each part constrain the degrees of freedom of the other side part. And this causes the stiffness of whole structure to be increased. This paper will cover concepts, design, analysis and experiments of this structure.

• Structural Engineering and Mechanics
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• v.47 no.6
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• pp.857-879
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• 2013

Numerical damage assessment of Van train station building consisting of three RC blocks due to 2011 Van Earthquakes by nonlinear dynamic analysis is presented. The structural model is created with rigid-end offsets and plastic hinges for nonlinear analysis. Rigid-end offsets are considered for connection areas and proposed for wall-supported elements. In wall-supported elements, walls take place in a limited part of the columns. Nonlinear dynamic analysis of the building with and without rigid-end offsets is performed by using real earthquake records and results are compared. The results show that rigid-end offsets have significant effects on the seismic behavior of the structures.