Modelling of Structural Adhesives for Body Stiffness Analysis in Automobile (차체 강성해석을 위한 구조용 접착제 해석모델링 연구)
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- Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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- 2007.11a
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- pp.1410-1414
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- 2007
In modern automobile body manufacturing, the structural adhesive bonding is recognized to one of new joining techniques for the purpose of light weight body and its application scope in the automobile body has been gradually magnified. Specially, the structural adhesives have the advantages of not only enhancing the design flexibility of automobile body, but also improving automobile performances such as stiffness, crashworthiness and durability. In order to evaluate the performance simulation of the automobile body applied with structural adhesives, it is necessary to develop modeling techniques in the structural adhesives in advance. This paper aims to investigate modeling methodology of structural adhesive junctions for body stiffness simulation. Two main modeling points are the element selection for adhesives and the connectivity between adhesives and adherends. Both of the 1D element used in classical modeling and the 3D element which are more accurate are considered for the adhesives, and the congruent and incongruent mesh models of the adherends are compared for connectivity modeling. By applying the several kinds of modeling methodology to the simple structures, the simulation results are compared and some modeling guidelines are obtained.
For a rail traffic noise, a typical source has a length of 200m - 400m so that the noise pollution areas have been located in the transition regions where the sound level drops between 3dB/dd and 6dB/dd. Therefore, in this region, parameters such as a horizontal distance from the track, the geometry of the ground surface, the environmental effect, and the boundary impedance condition play import roles, especially in our nation's situation. In this study, modelling techniques for the finite length of noise source have been investigated in order to evaluate the rail traffic noise level. Then. noise correction value .
In recent decades there has been a trend towards improved mechanical characteristics of materials used in footbridge construction. It has enabled engineers to design lighter, slender and more aesthetic structures. As a result of these construction trends, many footbridges have become more susceptible to vibrations when subjected to dynamic loads. In addition to this, some inherit modelling uncertainties related to a lack of information on the as-built structure, such as boundary conditions, material properties, and the effects of non-structural elements make difficult to evaluate modal properties of footbridges, analytically. For these purposes, modal testing of footbridges is used to rectify these problems after construction. This paper describes an arch type steel footbridge, its analytical modelling, modal testing and finite element model calibration. A modern steel footbridge which has arch type structural system and located on the Karadeniz coast road in Trabzon, Turkey is selected as an application. An analytical modal analysis is performed on the developed 3D finite element model of footbridge to provide the analytical frequencies and mode shapes. The field ambient vibration tests on the footbridge deck under natural excitation such as human walking and traffic loads are conducted. The output-only modal parameter identification is carried out by using the peak picking of the average normalized power spectral densities in the frequency domain and stochastic subspace identification in the time domain, and dynamic characteristics such as natural frequencies mode shapes and damping ratios are determined. The finite element model of footbridge is calibrated to minimize the differences between analytically and experimentally estimated modal properties by changing some uncertain modelling parameters such as material properties. At the end of the study, maximum differences in the natural frequencies are reduced from 22% to only %5 and good agreement is found between analytical and experimental dynamic characteristics such as natural frequencies, mode shapes by model calibration.
Although the aircraft industry was the first to use fibre composites, now they are increasingly used in a range of structural applications such as flooring, decking, platforms and roofs. Interlayer delamination is a major failure mode which threatens the reliability of composite structures. Delamination can grow in size under increasing loads with time and hence leads to severe loss of structural integrity and stiffness reduction. Delamination reduces the natural frequency and as a consequence may result in resonance. Hence, the study of the effects of delamination on the free vibration behaviour of multilayer composite structures is imperative. The focus of this paper is to develop a 3D FE model and investigate the free vibration behaviour of fibre composite multilayer sandwich panels with interlayer delaminations. A series of parametric studies are conducted to assess the influence of various parameters of concern, using a commercially available finite element package. Additionally, selected points in the delaminated region are connected appropriately to simulate bolting as a remedial measure to fasten the delamination region in the aim of reducing the effects of delamination. First order shear deformation theory based plate elements have been used to model each sandwich layer. The findings suggest that the delamination size and the end fixity of the plate are the most important factors responsible for stiffness reduction due to delamination damage in composite laminates. It is also revealed that bolting the delaminated region can significantly reduce the natural frequency variation due to delamination thereby improving the dynamic performance.
Carton clamp truck is widely perceived as the high-efficient handling equipment of factory premises and warehouse by its capability of palletless handling. Therefore, the significance of a lab-based handling simulation is becoming higher with the growth of clamp truck usage. In this study, preliminary FEA and design of handling test courses for the lab-based simulation of carton clamp truck handling were performed, and the PSD analyses were performed for the modified one for the test course proposed by Park et al. (2017) as well as ASTM D 6055 and ISTA 3B standards. For the vibration in all directions, the vibration energy intensity analyzed by ISTA 3B standard showed higher than that by the other two cases. A FEA was performed for the handling operation of the sudden stop of the clamps after lifting the target HCP (heavyweight refrigerator corrugated package, w=180 kgf) up to the specified height. The slip distance between the clamp arm and the target HCP was 0.85 mm. The simulation result of 0.85 mm was 3.7 times lower than the experimental result (3.2 mm) obtained by Park et al. (2017), and it was estimated that the deviation comes from both the experimental error by weight imbalance of target HCP, and excessive simplification during the FE modelling of target HCP.
The bogie between the track and the railway vehicle body, is one of the most important component in railroad vehicle. Its effects on the safety of both passengers and vehicle itself, and on the overall performance of the vehicle such as riding quality, noise and vibration are critical. The bogie is mainly consisted of the bogie frame, suspensions, wheels and axles, braking system, and transmission system. The complex shapes of the bogie frame and the complicate loading condition (both static and dynamic) induced in real operation make it difficult to design the bogie frame fulfilling all the requirements. The complicated loads applied to the bogie frame are i) static load due to the weight of the vehicle and passengers, ii) quasi-static load due to the rolling in curves iii) dynamic load due to the relative motion between the track, bogie, and vehicle body. In designing the real bogie frame, fatigue analysis based on the above complicated loading conditions is a must. In this study, stress analysis of the bogie frame has been performed for the various loading conditions according to the UIC Code 6 15-4. Magnitudes of the stress amplitude and mean stress were estimated based on the stress analysis results to simulate the operating loads encountered in service. Fatigue strength of the bogie frame was evaluated by using the constant life diagram of the material. 3-D surface modelling, finite element meshing, and finite element analysis were performed by Pro-Engineer, MSC/PATRAN, and MSC/NASTRAN, respectively.
Car seat is one the most important element to make comfortable drivability. It can absorb the impact or vibration during driving state. In addition to those factors, it is needed to have enough strength for passenger safety. From energy efficiency and environmental point of view lighter passenger car seat frame becomes hot issue in the auto industry. In this paper, weight optimization methodology is investigated for commercial car seat frame using CAE. Optimized designs for seat frame are developed using commercially available finite element code(ANSYS) and design of experiment method. At first, car seat frame is modelled using 3-D computer aided design tool(CATIA) and simplified for finite element modelling. Finite element analysis is carried out for the case of FMVSS 202 Head Restraint test to check the strength of the original seat frame. Two base brackets are selected as optimized elements that are the heaviest parts in the seat frame. After finite element analysis for the brackets with similar load condition to the previous test optimization technique is applied for 10% to 50% weight reduction. Design of experiment is utilized to obtain optimization design for the bracket based on the modified 50% weight reduction model in which outer shape of the bracket is conserved. Weight optimization models result in the decrease of the strength in spite of weight reduction. The more design points should be considered to get better optimized model. The more advanced optimization technique may be utilized for more parts of the seat frame to increase whole seat frame characteristics in the future.
The wall shear stress in the vicinity of end-to end anastomoses under steady flow conditions was measured using a flush-mounted hot-film anemometer(FMHFA) probe. The experimental measurements were in good agreement with numerical results except in flow with low Reynolds numbers. The wall shear stress increased proximal to the anastomosis in flow from the Penrose tubing (simulating an artery) to the PTFE: graft. In flow from the PTFE graft to the Penrose tubing, low wall shear stress was observed distal to the anastomosis. Abnormal distributions of wall shear stress in the vicinity of the anastomosis, resulting from the compliance mismatch between the graft and the host artery, might be an important factor of ANFH formation and the graft failure. The present study suggests a correlation between regions of the low wall shear stress and the development of anastomotic neointimal fibrous hyperplasia(ANPH) in end-to-end anastomoses. 30523 T00401030523 ^x Air pressure decay(APD) rate and ultrafiltration rate(UFR) tests were performed on new and saline rinsed dialyzers as well as those roused in patients several times. C-DAK 4000 (Cordis Dow) and CF IS-11 (Baxter Travenol) reused dialyzers obtained from the dialysis clinic were used in the present study. The new dialyzers exhibited a relatively flat APD, whereas saline rinsed and reused dialyzers showed considerable amount of decay. C-DAH dialyzers had a larger APD(11.70
The wall shear stress in the vicinity of end-to end anastomoses under steady flow conditions was measured using a flush-mounted hot-film anemometer(FMHFA) probe. The experimental measurements were in good agreement with numerical results except in flow with low Reynolds numbers. The wall shear stress increased proximal to the anastomosis in flow from the Penrose tubing (simulating an artery) to the PTFE: graft. In flow from the PTFE graft to the Penrose tubing, low wall shear stress was observed distal to the anastomosis. Abnormal distributions of wall shear stress in the vicinity of the anastomosis, resulting from the compliance mismatch between the graft and the host artery, might be an important factor of ANFH formation and the graft failure. The present study suggests a correlation between regions of the low wall shear stress and the development of anastomotic neointimal fibrous hyperplasia(ANPH) in end-to-end anastomoses. 30523 T00401030523 ^x Air pressure decay(APD) rate and ultrafiltration rate(UFR) tests were performed on new and saline rinsed dialyzers as well as those roused in patients several times. C-DAK 4000 (Cordis Dow) and CF IS-11 (Baxter Travenol) reused dialyzers obtained from the dialysis clinic were used in the present study. The new dialyzers exhibited a relatively flat APD, whereas saline rinsed and reused dialyzers showed considerable amount of decay. C-DAH dialyzers had a larger APD(11.70