• Design & Manufacturing
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• 제17권1호
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• pp.48-55
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• 2023

In this study, on the structure simulation for manufacturing a high strength/light weight 48V battery housing for a mild hybrid vehicle was conducted. Compression analysis was performed in accordance with the international safety standards(ECE R100) for existing battery housings. The effect of plastic materials on compressive strength was analyzed. Three models of truss, honeycomb and grid rib for the battery housing were designed and the strength characteristics of the proposed models were analyzed through nonlinear buckling analysis. The effects of the previous existing rib, double-sided grid rib, double-sided honeycomb rib and double-sided grid rib with a subtractive draft for the upper cover on the compressive strength in each axial direction were examined. It was confirmed that the truss rib reinforcement of the battery housing was very effective compared to the existing model and it was also confirmed that the rib of the upper cover had no significant effect. In the results of individual 3-axis compression analysis, the compression load in the lateral long axis direction was the least and this result was found to be very important to achieve the overall goal in designing the battery housing. To reduce the weight of the presented battery housing model, the cell molding method was applied. It was confirmed that it was very effective in reducing injection pressure, clamping force and weight.

• Journal of Computing Science and Engineering
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• 제4권3호
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• pp.207-224
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• 2010

This paper presents a compression scheme for mesh geometry, which is suitable for mobile graphics. The main focus is to enable real-time decoding of compressed vertex positions while providing reasonable compression ratios. Our scheme is based on local quantization of vertex positions with mesh partitioning. To prevent visual seams along the partitioning boundaries, we constrain the locally quantized cells of all mesh partitions to have the same size and aligned local axes. We propose a mesh partitioning algorithm to minimize the size of locally quantized cells, which relates to the distortion of a restored mesh. Vertex coordinates are stored in main memory and transmitted to graphics hardware for rendering in the quantized form, saving memory space and system bus bandwidth. Decoding operation is combined with model geometry transformation, and the only overhead to restore vertex positions is one matrix multiplication for each mesh partition. In our experiments, a 32-bit floating point vertex coordinate is quantized into an 8-bit integer, which is the smallest data size supported in a mobile graphics library. With this setting, the distortions of the restored meshes are comparable to 11-bit global quantization of vertex coordinates. We also apply the proposed approach to compression of vertex attributes, such as vertex normals and texture coordinates, and show that gains similar to vertex geometry can be obtained through local quantization with mesh partitioning.

• Geomechanics and Engineering
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• 제18권2호
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• pp.133-140
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• 2019

Strain-rate and temperature have significant effects on the one-dimensional (1D) compression behavior of soils. This paper focuses on the bonding degradation effect of soil structure on the time and temperature dependent behavior of soft structured clay. The strain-rate and temperature dependency of preconsolidation pressure are investigated in double logarithm plane and a thermal viscoplastic model considering the combined effect of strain-rate and temperature is developed to describe the mechanical behavior of unstructured clay. By incorporating the bonding degradation, the model is extended that can be suitable for structured clay. The extended model is used to simulate CRS (Constant Rate of Strain) tests conducted on structural Berthierville clay with different strain-rates and temperatures. The comparisons between predicted and experimental results show that the extended model can reasonably describe the effect of bonding degradation on the stain-rate and temperature dependent behavior of soft structural clay under 1D condition. Although the model is proposed for 1D analysis, it can be a good base for developing a more general 3D model.

• Composites Research
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• 제37권3호
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• pp.143-149
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• 2024

본 논문에서는 친환경 포장재인 골판지의 기계적 물성을 측정하고, 이를 LS-DYNA의 MAT_PAPER 모델에 적용하여 유한요소해석을 수행하였다. MAT_PAPER는 주로 종이의 거동을 모델링 하기 위한 재료모델이지만 본 연구를 통해 골판지에 대해서도 적용 가능함을 보였다. 인장, 압축, 전단 거동에 대하여 골판지의 방향별 기계적 물성을 측정 및 분석하고, 이를 바탕으로 6개의 항복면을 도출하여 MAT_PAPER 모델에 통합하였다. 재료시험 시편의 유한요소해석과 골판지 사각관의 저속 붕괴해석 결과를 각 실험 결과와 비교함으로써, 골판지의 거동을 등가적으로 잘 고려할 수 있음을 보였다. 그러나 해당 모델은 골판지의 변형률 속도효과를 고려하지 못하므로, 골판지의 원소재인 원심지의 고속물성을 측정하여 이를 보정하였으며, 이에 따라 골판지 사각관의 고속 압괴 실험 결과와 잘 일치함을 보였다.

• Geomechanics and Engineering
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• 제31권3호
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• pp.305-318
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• 2022

Permeable reactive barriers used for groundwater treatment require proper estimation of the reactive material behavior regarding the emplacement method. This study evaluates the dry emplacement of zeolite (clinoptilolite) to be used as a reactive material in the barrier by carrying out several geotechnical laboratory tests. Dry zeolite samples, exhibited higher wetting-induced compression strains at the higher vertical stresses, up to 12% at 400 kN/m². The swelling potential was observed to be limited with a 3.5 swell index and less than 1% free swelling strain. Direct shear tests revealed that inundation reduces the shear strength of a dry zeolite column by a maximum of 10%. Falling head permeability tests indicate decreasing permeability values with increasing the vertical effective stress. Regarding self-loading and inundation, the porosity along the zeolite column was calculated using a proposed 1D numerical model to predict the permeability with depth considering the laboratory tests. The calculated discharge efficiency was significantly decreased with depth and less than 2% relative to the top for barrier depths deeper than 20 m. Finally, the importance of directional dependence in the permeability of the zeolite medium for calibrating 2D finite element flow analysis was highlighted by bench-scale tests performed under 2D flow conditions.

• International Journal of Concrete Structures and Materials
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• 제11권1호
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• pp.135-149
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• 2017

The prediction of the actual ultimate capacity of confined concrete columns requires partial confinement utilization under eccentric loading. This is attributed to the reduction in compression zone compared to columns under pure axial compression. Modern codes and standards are introducing the need to perform extreme event analysis under static loads. There has been a number of studies that focused on the analysis and testing of concentric columns. On the other hand, the augmentation of compressive strength due to partial confinement has not been treated before. The higher eccentricity causes smaller confined concrete region in compression yielding smaller increase in strength of concrete. Accordingly, the ultimate eccentric confined strength is gradually reduced from the fully confined value $f_{cc}$ (at zero eccentricity) to the unconfined value $f^{\prime}_c$ (at infinite eccentricity) as a function of the ratio of compression area to total area of each eccentricity. This approach is used to implement an adaptive Mander model for analyzing eccentrically loaded columns. Generalization of the 3D moment of area approach is implemented based on proportional loading, fiber model and the secant stiffness approach, in an incremental-iterative numerical procedure to achieve the equilibrium path of $P-{\varepsilon}$ and $M-{\varphi}$ response up to failure. This numerical analysis is adapted to assess the confining effect in rectangular columns confined with conventional lateral steel. This analysis is validated against experimental data found in the literature showing good correlation to the partial confinement model while rendering the full confinement treatment unsafe.

• 한국강구조학회 논문집
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• 제29권4호
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• pp.281-289
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• 2017

현재의 AASHTO LRFD 및 Eurocode 3 기준은 수평보강 플레이트거더의 휨강도를 과소 평가하는 것으로 나타났다. 이는 웨브보강으로 인한 웨브-플랜지 상호작용을 적절히 고려치 않는 것에 그 원인이 있다. 즉, 웨브 보강 시 압축플랜지의 회전을 구속하는 효과가 증가하여 압축플랜지의 좌굴강도가 증가한다. 또한 압축플랜지와 수평보강재가 웨브의 회전을 구속함으로써 웨브의 일정 영역이 항복강도에 도달하게 된다. 본 연구에서는 수평보강재로 1단 보강된 플레이트 거더에 대해 압축플랜지의 좌굴강도 증가와 웨브의 실제 응력분포를 고려하여 휨강도를 합리적으로 평가하기 위한 모델을 제안하였다. 일반강(SM490) 및 고강도강(HSB800) 플레이트거더에 대해 비선형해석으로부터 휨강도를 평가하고 본 제안 모델의 적용성을 분석하였다.

• 한국초전도ㆍ저온공학회논문지
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• 제22권4호
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• pp.24-30
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• 2020

The test results of the ITER toroidal field conductors demonstrated a decrease of the current sharing temperature (Tcs) with an increase in the number of electromagnetic cycles in general. This is associating with several factors. One of them is the superconducting Nb3Sn filaments cracking and another one is the redistribution of the relative deformation of the Nb3Sn strands under Lorentz forces. Despite these factors, some conductors have shown the absence or significantly less degradation of Tcs during electromagnetic cycling. This article considers another possible reason for a more stable conductors Tcs behavior, namely, the local compression of Nb3Sn wires in the cross section of a conductor. In this article presents the results of a quantitative analysis Nb3Sn superconducting filaments cracking of strands extracted from a conductor that has passed electromagnetic cycling and the model of a conductor compaction, as well as calculation results based on this model are presented also.

• 소성∙가공
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• 제24권3호
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• pp.194-198
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• 2015

Microstructure based FE simulations were conducted to investigate the micro-mechanical properties of ferrite-martensite dual-phase steels. The FE model was built based on real microstructure images which were characterized by optical microscopy through the thickness direction. Serial sectioned 2D images were converted into semi-2D representative volume elements (RVEs) model. Each RVE model was subjected to a non-proportional loading condition and the mechanical response was analyzed on both the macroscopic and microscopic levels. Macroscopically, stress-strain curves were described under tension-compression and tension-orthogonal tension conditions and the Bauschinger effect was well captured for both loading paths. In addition, micromechanical properties were investigated in the view of stress-strain partitioning and strain localization during monotonic tension.

• 한국지능시스템학회논문지
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• 제9권4호
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• pp.436-443
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• 1999

대부분의 3차원 물체 복원 기술은 물체를 다수의 평면으로 나누고 물체의 각 표면을 근사시켜 표현한다. 주어진 분류치를 사용하여 mesh를 초기화시키는 Marching Cubes 알고리듬과 Delaunay Tetrahedrisation이 널리 사용되고 있다. 이와 더불어 deformable 모델은 적은수의 가정만으로도 다양한 종류의 데이터들에 대한 복원 및 재구성을 할수 있기 때문에 일반적인 물체복원에 적합하다. 현재 defrmable 모델이 기반이 된 복원 시스템에 대한 연구가 활발히 진행중이다. 본 논문에서는 곡면으로 이루어진 물체에 대해서 적응 simplex mesh 기술을 바탕으로 3차원 물체를 압축 복원하는 방법을 제시한다. 이방법은 미리 정해진 mesh 구조를 변형시키고 곡률과 같은 기하학적인 특성들을 다시 설정하면서 본래의 3차원 물체로 접근시킨다. 시뮬레이션을 통해서 높은 압축률로 물체를 복원하고 물체의 모양을 최적으로 기술하기 위해 정점들이 곡률이 높은 곳으로 집중되는 것을 보인다.