scholarly journals Efficient Load Sampling for Worst-Case Structural Analysis Under Force Location Uncertainty

Author(s):  
Yining Wang ◽  
Erva Ulu ◽  
Aarti Singh ◽  
Levent Burak Kara

An important task in structural design is to quantify the structural performance of an object under the external forces it may experience during its use. The problem proves to be computationally very challenging as the external forces’ contact locations and magnitudes may exhibit significant variations. We present an efficient analysis approach to determine the most critical force contact location in such problems with force location uncertainty. Given an input 3D model and regions on its boundary where arbitrary normal forces may make contact, our algorithm predicts the worst-case force configuration responsible for creating the highest stress within the object. Our approach uses a computationally tractable experimental design method to select number of sample force locations based on geometry only, without inspecting the stress response that requires computationally expensive finite-element analysis. Then, we construct a simple regression model on these samples and corresponding maximum stresses. Combined with a simple ranking based post-processing step, our method provides a practical solution to worst-case structural analysis problem. The results indicate that our approach achieves significant improvements over the existing work and brute force approaches. We demonstrate that further speedup can be obtained when small amount of an error tolerance in maximum stress is allowed.

2020 ◽  
Vol 10 (17) ◽  
pp. 6063
Author(s):  
Polychronis Spanoudakis ◽  
Evangelos Christenas ◽  
Nikolaos C. Tsourveloudis

This study focuses on the structural analysis of the front single-sided swingarm of a new three-wheel electric motorcycle, recently designed to meet the challenges of the vehicle electrification era. The primary target is to develop a swingarm capable of withstanding the forces applied during motorcycle’s operation and, at the same time, to be as lightweight as possible. Different scenarios of force loadings are considered and emphasis is given to braking forces in emergency braking conditions where higher loads are applied to the front wheels of the vehicle. A dedicated Computer Aided Engineering (CAE) software is used for the structural evaluation of different swingarm designs, through a series of finite element analysis simulations. A topology optimization procedure is also implemented to assist the redesign effort and reduce the weight of the final design. Simulation results in the worst-case loading conditions, indicate strongly that the proposed structure is effective and promising for actual prototyping. A direct comparison of results for the initial and final swingarm design revealed that a 23.2% weight reduction was achieved.


2019 ◽  
Vol 2019 ◽  
pp. 1-8 ◽  
Author(s):  
Shijun Chen ◽  
Qi Zhang ◽  
Surong Huang

To more efficiently design high performance vehicular permanent magnet motor, an electromagnetic-thermal integration design method is presented, which considers both the electromagnetic properties and the temperature rise of motor winding when determining the main dimensional parameters of the motor. Then a 48-slot and 8-pole vehicular permanent magnet motor is designed with this method. The thermomagnetic coupling design is simulated and validated on the basis of multiphysical domain on finite element analysis. Then the prototype is analyzed and tested on a newly built motor experiment platform. It is shown that the simulation results and experimental results are consistent, which validate the accuracy and effectiveness of the new design method. Also this method is proved to well improve the efficiency of permanent magnet motor design.


Author(s):  
S Sumith ◽  
R Ramesh Kumar

In launch vehicles, cryogenic propulsion stages store liquid oxygen (LOX) at 76 K and liquid hydrogen (LH2) at 20 K, generally in two separate insulated tanks connected through tubular truss components. Consequently, load transfer from the LH2 tank to the LOX tank is very much localized, resulting in a nonoptimal design. This article presents an alternative single tankage design using a common bulkhead (CBH) to enhance the payload capability, which enables maintaining LH2 temperature within a specified temperature when exposed to a temperature gradient. A sandwich insulator using aramid honeycomb embedded with polyimide foam keeps the LH2 temperature within 20 ± 1 K is proposed, based on transient heat transfer analysis for 1000 s. The foam-filled honeycomb core is treated as equivalent foam in the analysis as the thermal conductivity of the core and the foam is quite close. The efficacy of the insulator is established by an experiment to measure the back wall temperature when liquid nitrogen is loaded on the top skin of the panel, and the insulator maintains a temperature gradient of 123 K for 1000 s. A good agreement is obtained between the transient finite element analysis results with experimental data. An externally insulated LOX tank configuration with an optimum length of the skirt–cylinder where the temperature reaches 80 K is arrived at based on slosh, buckling, and thermal analyses. No thermal gradient is found across the thickness of the skirt, while the thermal gradient is observed along the length of the skirt as anticipated. An integrated thermo-structural analysis of the cryo-system is carried out considering temperature-dependent material properties. A positive margin for the skirt is obtained. A payload gain of 366 kg is estimated based on the present study for the new design option with a CBH and skirt as compared to the traditional tubular truss arrangements.


2011 ◽  
Vol 346 ◽  
pp. 379-384
Author(s):  
Shu Bo Xu ◽  
Yang Xi ◽  
Cai Nian Jing ◽  
Ke Ke Sun

The use of finite element theory and modal analysis theory, the structure of the machine static and dynamic performance analysis and prediction using optimal design method for optimization, the new machine to improve job performance, improve processing accuracy, shorten the development cycle and enhance the competitiveness of products is very important. Selected for three-dimensional CAD modeling software-UG NX4.0 and finite element analysis software-ANSYS to set up the structure of the beam finite element model, and then post on the overall structure of the static and dynamic characteristic analysis, on the basis of optimized static and dynamic performance is more superior double wall structure of the beam. And by changing the wall thickness and the thickness of the inner wall, as well as the reinforcement plate thickness overall sensitivity analysis shows that changes in these three parameters on the dynamic characteristics of post impact. Application of topology optimization methods, determine the optimal structure of the beam ultimately.


2015 ◽  
Vol 809-810 ◽  
pp. 859-864
Author(s):  
Dănuţ Zahariea

In this paper, the finite element analysis for stress/deformation/modes of vibration for the centrifugal fan impeller with constant thickness backward-curved blades using CATIA software will be presented. The principal steps of the finite element analysis procedure using CATIA/Generative Structural Analysis environment will be presented: creating the 3D model; configuring the mesh; applying the restraints; applying the loads; running the numerical static analysis and the numerical frequency analysis; interpreting the results and observing the modes of vibration correlating with the impeller mode shape. This procedure will be used for 4 different centrifugal fan impellers according with the 4 blade design methods and the results will be comparatively analyzed. For each design method, two materials will be used: steel with density of 7860 kg/m3 and aluminium with density of 2710 kg/m3. Two important results have been obtained after the structural analysis: under the working conditions considered for the analysis, all 4 blade design methods leads to impellers with very good mechanical behaviour; any frequency of the main modes of vibrations for all blade design methods and for both materials is not in phase with the impeller speed, thus the possibility of resonance being eliminated.


Author(s):  
Lei Fu ◽  
Yan Shi ◽  
Qinghua Deng ◽  
Huaizhi Li ◽  
Zhenping Feng

The aerodynamic performance, structural strength and wheel weight are three important factors in the design process of the radial turbine. This paper presents an investigation on these aspects and develops an optimization design approach for radial turbine with consideration of the three factors. The aerodynamic design for the turbine wheel with inlet diameter of 230mm for 100kW-class microturbine unit is carried out firstly as the original design. Then, the cylinder parabolic geometrical design method is applied to the wheel modeling and structural design, but the maximum stress predicted by Finite Element Analysis greatly exceeds the yield limit of material. Furthermore, the wheel weight is above 7.2kg thus bringing some critical difficulties for bearing design and turbine operation. Therefore, an integrated optimization design method for radial turbine is studied and developed in this paper with focus on the wheel design. Meridional profiles and shape lines of turbine wheel are optimized with consideration of the whole wheel weight. Main structural modeling parameters are reselected to reduce the wheel weight. Trade-off between aerodynamic performance and strength performance is highly emphasized during the optimization design. The results show that the optimized turbine wheel gets high aerodynamic performance and acceptable stress distribution with the weight less than 3.8kg.


2005 ◽  
Vol 6-8 ◽  
pp. 753-762
Author(s):  
R. Bahloul ◽  
Phillippe dal Santo ◽  
Ali Mkaddem ◽  
A. Potiron

Bending has significant importance in the sheet metal product industry. Moreover, the springback of sheet metal should be taken into consideration in order to produce bent sheet metal parts within acceptable tolerance limits and to solve geometrical variation for the control of manufacturing process. Nowadays, the importance of this problem increases because of the use of sheet-metal parts with high mechanical characteristics (High Strength Low Alloy steel). This work describes robust methods of predicting springback of parts in 3D modelling subjected to bending and unbending deformations. Also the effects of tool geometry in the final shape after springback are discussed. The first part of this paper presents the laboratory experiments in wiping die bending, in which the influence of process variables, such as die shoulder radius, punch-die clearance, punch nose radius and materials properties were discussed. The second part summarises the finite element analysis by using ABAQUS software and compares these results with some experimental data. It appeared that the final results of the FEM simulation are in good agreement with the experimental ones. An optimisation methodology based on the use of experimental design method and response surface technique is proposed in the third part of this paper. That makes it possible to obtain the optimum values of clearance between the punch and the die and the optimum die radius which can reduce the springback without cracking and damage of product.


2014 ◽  
Vol 1049-1050 ◽  
pp. 828-832
Author(s):  
J.R. Yang

The aim of this study was to obtain the method of the green design and modular design that oriented construction machinery products. A variety of modern design tools such as the finite element analysis software package and optimize design package and a two-factor evaluation fuzzy modelare used to analyze and Evaluation the green degree and the module degree of the construction machinery. Some modern mathematical tools such as AHP and fuzzy comprehensive evaluation method are used to calculate and evaluate the green degree and the module degree in construction machinery design. The proposed design method can meet the requirements of the green degree and the module degree of the construction machinery.


2014 ◽  
Vol 11 (4) ◽  
pp. 65-69
Author(s):  
Patil Tushar Vishwas ◽  
◽  
Supale Jayant P ◽  
Vinaay Patil

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