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THICKNESS OPTIMIZATION OF AN AUTOMOBILE BODY FOR NATURAL FREQUENCY MAXIMIZATION
Henry Panganiban,Gang-Won Jang,Tae-Jin Chung,Young-Min Choi 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.5
The paper presents design optimization of an automobile body for dynamic stiffness improvement. The thicknesses of plates making-up the monocoque body of an automobile were employed as design variables for optimization and the objective was to increase the first torsional and bending natural frequencies. By allotting one design variable to each plate of the body, compared to previous works based on element-wise design variables, design space of optimization was reduced to a large extent and numerical instabilities such as checkerboard pattern was efficiently evaded. The method resulted to a considerable amount of increase in the automobile body’s torsional and bending natural frequencies. Considering manufacturability of the optimized result, the converged values of plate thicknesses were approximated to commercially-available values by appropriately reflecting their design sensitivities.
Topology Optimization of Support Structure for Long-Range Boom Lift
Henry Panganiban,Woncheol Kim,Tae-Jin Chung 한국자동차공학회 2012 한국자동차공학회 학술대회 및 전시회 Vol.2012 No.11
Structural design of long-range telescopic boom system used for lifting work platform requires serious consideration of structural integrity and reliability. Component design can be rapidly and economically conceptualized using CAE tools. In this work, the concept design of support structure for a long-range telescopic boom lift is obtained using topology optimization method. The classical topology optimization formulation is implemented with consideration on various load cases encompassing actual operation conditions. Transfer mechanism of loads from the work platform and boom self-weight into the support structure is analyzed and verified by FEM. In the analytical solution, boom self-weight is defined by its magnitude and location in space while bar or truss elements are used to model the boom structure with the corresponding point loads. Agreement of the calculated reaction forces is very close. The support structure is isolated with the reaction forces imposed on predefined loading points of the structure and topology optimization is carried out. This method can significantly reduce FE-model size and consequently computation time allowing more opportunities to explore possible design configurations within the capability of the topology optimization tool being used. The topology or material layout of the support structure at the converged iteration will be translated into manufacturable final design using a CAD tool.
Recent Development in Non-Contact NDE Using Electromagnetic Acoustic Transducer (EMAT) Technology
Henry Panganiban,Tae Jin Chung,Gang Won Jang 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.9
EMATS is the commonly used non-contact inspection and monitoring technology for non-destructive evaluation especially in industrial applications. Various developments and technology have emerged so fast. Some of these developments are electromagnetic ultrasonic 3D modeling with FEM, phase array operation of EMATS, and the tests for the possibility to use dispersive Shear Horizontal modes for NOT. In this paper, some of the emerging technology and recent advances in non-contact NDE using EMATS were pointed out.
Weight Reduction of Boom System of an Aerial Lift Truck Using the Taguchi Method
Henry Panganiban,Hae-Rim Lee(이해림),Yong Hong(홍룡),Gang-Won Jang(장강원),Tae-Jin Chung(정태진) 한국자동차공학회 2011 한국자동차공학회 부문종합 학술대회 Vol.2011 No.5
Weight reduction by optimizing the design of the boom system for the aerial platform truck is performed using the Taguchi method. Matrix experiments were performed using the constructed orthogonal array of design parameters or factors with a maximum of three settings or levels for each factor. The factors considered are the overlap length between booms, crosssection shape and plate thicknesses. Experiments were carried out with parametric analysis setup in ANSYS Workbench while the optimization is done in Minitab. The CAE-based optimization method enables concept design and verification to be performed over a short period of time. The optimal design has reduced the weight of the boom system by over 10% with structural performance close to the original design.
Optimization of flatbed trailer frame using the ground beam structure approach
Henry P. Panganiban,Tae-Jin Chung,장강원 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.5
An alternative lightweight flatbed trailer design is achieved through a multi-stage optimization procedure. Topology optimization is used to obtain the optimal layout of flatbed trailer frame beams that provide minimum compliance when subjected to bending loads and exhibits maximum torsional natural frequency. The ground structure approach is used to define the trailer frame layout by generating numerous beams connected to predefined points in the trailer. Topology optimization is formulated as a multi-objective problem subject to a mass constraint. Responses and sensitivities are evaluated using ANSYS, and the optimization problem is solved using the moving asymptotes method. The thicknesses, widths, and heights of the C-channel beams are optimized for further weight reduction while at least maintaining the structural performances of the original design. Size and shape optimizations are performed using OptiStruct. The new optimal design is approximately 13% (275 kg) lighter than and as stiff as the original design for bending loads. However, the former has 3.5 times higher torsional natural frequency than the latter. Moreover, the new optimal design has positive manufacturability because the channel beams will be made out of commercially available sheet metals. The same fabrication technology as for a conventional flatbed trailer is possibly to be used.
Topology optimization of pressure-triggered compliant mechanisms
헨리 팡가니반(Henry Panganiban),장강원(Gang Won Jang),정태진(Chung Tae Jin) 한국자동차공학회 2008 한국자동차공학회 지부 학술대회 논문집 Vol.2008 No.11
The paper presents an alternative approach for the topology optimization of compliant mechanism for micro devices under pressure input force. A well-known optimization formulation was used along with the proposed new form of constraint based on the static stiffness of the structure. The pure-displacement (standard) formulation was also used for the finite element analysis. Shortcomings brought by the associated pressure load problem were addressed with the use of incompressible material and nonconforming finite elements. Problems in two and three dimensions were solved as examples.
헨리 팡가니반(Henry Panganiban),백태현(Tae Hyun Baek),정태진(Tae Jin Chung) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.11
The investigation of the significant effects of stress raisers demands well-defined evaluation technique to accurately determine the stress on the geometric boundary. While various measuring tools are available, the hybrid method employing the least-square method integrated with Laurent series representation of the stress function was used to estimate dependable stresses around the circular hole in a tensile-loaded plate out of experimental xdisplacement data away from the boundary. Traction-free conditions were satisfied at the geometric discontinuity using conformal mapping and analytic continuation. Results from this approach were closely comparable with that of FEM.
TOPOLOGY OPTIMIZATION USING P1-NONCONFORMING QUADRILATERAL FINITE ELEMENT
헨리 팡가니반(Henry Panganiban),장강원(Gang-Won Jang),정태진(Tae-Jin Chung) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.11
An alternative approach for topology optimization involving incompressible material based on puredisplacement formulation is presented. The approach takes advantage of the promising characteristics of P1-nonconforming element that includes locking-free, linear shape functions defined at element vertices and less degrees of freedom compared to other finite elements used in existing methods. Problems dealing with incompressible materials and pressure-loaded structures are solved for verification. Optimization results obtained from all considered problems are in close agreement with those found in published works.