Computer Aided Engineering Program Research Articles

Optimizing Sheet Metal Formation through Advanced Hydroforming Simulation Technique

In this study, we investigate into the simulation of sheet metal hydroforming for crafting the cap of the axle-hub of a tip trailer within our manufacturing facility. This cap serves a crucial role in safeguarding wheel bearings from the detrimental effects of dust, sand, and dirt. The motivation for this work arises from the challenges encountered during the fixation of a conventional dust cap, which often falls off when subjected to pressure or threading, particularly when the tractor is in motion. The innovative approach pursued in this research involves the utilization of lightweight aluminum sheet metal for cap production, owing to its facile formability. The cap design incorporates four evenly distributed holes around its circumference and secures to the flange using screws. Prior to the manufacturing phase, a simulation of the cap-forming process was conducted using ANSYS Model 15, a computer-aided engineering program. The necessary models were crafted in CATIA, a computer-aided design program, streamlining the entire process to enhance efficiency, reduce costs, and minimize manpower requirements. The simulation encompassed three different thicknesses (1 mm, 2 mm, and 3 mm) for two distinct aluminum alloys, namely 1100 and 5652. The objective was to discern the optimal alloy for the forming process. Essential mechanical properties, including ultimate tensile strength, modulus of elasticity, and yield stress, were input into the ANSYS program to accurately reflect the materials' behavior during forming. The outcomes of our investigation revealed that aluminum alloy 5652 outperformed 1100 in terms of formability. The former exhibited a forming pressure of 300.2 MPa, while the latter required 298.3 MPa for the same forming depth (40 mm) across all three thickness variations. Additionally, the study demonstrated that 5652 is not only more efficient but also safer and more resilient than 1100.

The Use of Aluminium Alloy after High Plastic Deformation for Joining Riveted Structures.

This paper presents the results of a static and dynamic tensile test of an Al7.5Mg aluminium alloy taken from round bars made in the technology of hydrostatic extrusion. It is planned to use the Al7.5Mg aluminium alloy for joining riveted structures. Based on the obtained results, the nominal and true characteristics of the Al7.5Mg aluminium alloy, depending on the strain rate in the range from 0 to 2000 s−1, were developed. The failure criterion for tension was determined. The material characteristics were approximated by the Johnson–Cook equation, which can be used in CAE (computer-aided engineering) programs to simulate the impact processes. FEM (finite element method) simulation of the impact of the hammer on the part of the riveted aircraft structure was performed. The FEM simulation results were compared with the experimental results on a drop hammer to verify the material model. The following results were obtained: yield strength Re = 395.3 MPa; strength limit Rm = 523.1 MPa at deformation 0.067; Young’s modulus E = 7.9 × 104 MPa. The AL7.5Mg alloy after hydro-extrusion has favourable plastic and strength properties.

Multi-objective Optimization of a Mechatronic Solar Tracking Mechanisms

In this work, the multi-objective optimization of a dual-axis solar tracker is carried out by using a virtual prototyping software platform that integrates CAD (Computer Aided Design) – CATIA, MBS (Multi-Body Systems) – ADAMS and DFC (Design for Control) – EASY5 computer aided engineering programs. The solar tracking mechanism performs the bi-axial orientation of a PV panel, with the purpose to increase of the amount of incident solar radiation captured by the conversion system, thus improving its energy output. The optimization study aims to determine the optimal arrangement of the linear actuators that control the two degrees of freedom of the system (i.e. the diurnal and elevation movements of the PV panel) and the optimal tuning of their control elements (controllers), so that to minimize the energy consumption for performing the tracking and the tracking errors (relative to the imposed orientation program), while complying with the functional and constructive requirements/constraints coming from the type of actuator used in the application (which is a real/existing one). The tracking mechanism is approached/designed in mechatronic concept (i.e. concurrent engineering), by integrating the mechanical and control subsystems at the virtual prototype level.

Reconstruction of thermo-physical properties to improve material database for casting simulation

In this work, an advanced method is proposed for computational recovery of thermo-physical properties in a wide range from room temperature to values above the alloy melting point. This method allows us to improve material databases of CAE (Computer-Aided Engineering) programs for simulation of high-temperature technological processes. In most cases, computation of unsteady temperature fields is an important stage of CAE analysis in mechanical engineering. Moreover, various manufacturing technologies such as casting, welding, surface hardening, coating, heat treatment provide the desired material structure and its strength by controlling temperature field during solidification and subsequent cooling of a machine part. The problem of reliability in computer modeling arises from the fact that CAE programs usually are not equipped with comprehensive material databases. We have solved this problem especially for casting simulation and molding materials, which can differ in composition at different plants and therefore cannot be combined into a common database. To determine unknown thermo-physical properties, the temperature had been measured in several points of solidifying cylindrical sample initially, and the appropriate computer simulation of the test technology was performed. Then the difference between the calculated and experimental temperatures was minimized using the modified Levenberg-Marquardt optimization algorithm.

Stability Evaluation of the Transmission Line by using Galloping Simulation

Galloping phenomenon is one of the vibrations caused by icing. If galloping phenomenon continues, short-circuit or ground fault may occur, so analysis of galloping phenomenon through research on transmission line stability is necessary. The DenHartog method, which is frequently used for the galloping stability determination of the transmission line, considers only the vertical movement of the transmission line. In this study, we analyze the motion of multi-degree-of-freedom objects, using a computer aided engineering program. We modeled transmission lines as a multi mass-spring-damper systems using RecurDyn, which is a multibody commercial dynamics analysis program to analyze the galloping phenomenon dynamically. Damping inside transmission line derived from the Rayleigh damping theory through the free vibration experiment of transmission line. ANSYS Fluent, a flow analysis program, was used to derive the aerodynamic coefficients for transmission line with asymmetric cross-section. Using the derived aerodynamic coefficient, we confirmed the galloping occurrence condition of DenHartog method and modeled the wind load acting on the transmission line to conduct galloping simulation. Through the analysis of the motion of a multi-degree-of-freedom transmission line, the occurrence of galloping was classified into ovoid and vertical trajectories, and the case of no galloping was defined as regular trajectory, and the range of angle of attack that causes the instability of transmission lines was defined.

Systematic Approach to Optimize Injection Molding and Microstructural Analysis of Fiber Reinforced Resins for Anisotropic Mechanical Characterization

Fiber reinforced resin materials are increasingly being used in aviation, automotive, mass transportation and healthcare industries. Engineers are keen to explore new design concepts with such materials, since these materials promises to offer high strength to weight ratio, elimination of secondary operations and ease in process ability to form complex shaped parts through injection molding. The mechanical properties of molded parts made from such materials depends on the orientation of the reinforcing fibers. Such orientation occurs in fiber-reinforced plastics, since the fibers in the plastic melt during processing, will orient in different directions under the influence of shear forces that are driven by flow pattern. This paper provides details on systematic and abusive injection molding of test specimens and characterizing anisotropic mechanical data that can be used for fiber orientation predictions in computer aided engineering programs. Systematic molding as compared to abusive molding, identifies optimum molding parameters that reduces part–to-part variation during injection molding, thereby reduces part rejections. It provides optimum part performance during application and the process settings are repeatable and reproducible. The intention of this paper is to share widely such a method to make this process less of a skill or art. The mechanical properties covered here are elastic, shear modulus and poisson ratio. Scanning electron microscopy (SEM) analysis revealed that most of the fibers are aligned in melt flow direction for systematic molded plaques, leading to higher stiffness and strength characteristics as compared to transverse to melt flow.

Elastic Stress Analysis of St 37 and St 70 Steels with Finite Element Method

The basic logic in the finite element method is to simplify and solve a complex problem. In this method, the solution region is divided into a plurality of simple, small, connected, sub-regions called finite elements. In other words, the problem which is divided into parts connected by a plurality of joint points can be easily solved. St 37 and St 70 steels are materials used in the manufacturing of general building materials, produced by processing the hot-formed steel further through a cold drawing process. Ansys; is a computer aided engineering program where analysis and simulations can be performed in computer aided engineering studies. It enables effective studies in different disciplines such as mechanics, structural analysis, computational fluid dynamics and heat transfer. The finite element method, which enables the solution of complex engineering problems with controllable parts by simplifying, is a common and useful solution method used in many engineering applications. St and St 70 steels are modeled as three-dimensional I-beams 3 mm in thickness in Ansys program package in accordance with the finite element method. Finite element method helps simplifying complex engineering problems and solving them with controllable parts. Elastic stress analyses were performed in X, Y, Z axes by stabilizing the right and left supports of steel beams and applying a pressure of 100 MPa on the top flanges. It was observed in Ansys simulation analyses that elastic stress effect was higher in St 37 steel compared to St 70 steel.

Evaluation of Helmet Protection during Impact of Head to Ground and Impact of an Object to Head Using Finite Element Analysis

This report describes the results of a research project focused on helmet protection under impact of head to ground, and impact of an object to head. Three kinds of helmets were considered: construction, motorcycle and bicycle helmets. The goal of this project is to check the amount of stress absorbed by the skull and brain during the impact, as well as evaluate the maximum capacity of helmet protection. The material used for each helmet was the most common material in the current market, in order to make the results more realistic. The analysis consists of dynamic simulation of an impact in the helmet using Finite Element Analysis (FEA). First, the models were meshed using Hypermesh. After the modeling phase, analyses were made using ABAQUS (a computer aided engineering program) that shows the stresses and displacements experienced by the whole system: helmet, skull and brain. The results obtained from the analysis were displayed on charts that show the effect of the helmet based on different boundary conditions such as object height for the hard hat, and the rider speed for the bicycle and motorcycle helmets.

형체력에 따른 사출성형기 플렉스링크의 특성 분석

Reproducibility of injection molding machines are studied at the study of this time. We applied computer aided engineering program so it could generate clamping force, about 1,500 kN, to the nozzle center part of flex link in tie-bar and at this time, we made sure condition of stress distribution and transformation quantity in flex link. The result of computer aided engineering transformation quantity was confirmed that transformation of top area was 247~257 kN and bottom areas was 273~279 kN and also was confirmed that the stresses are distributed in a range of 57~750 N/mm2 from top to the bottom of the surface. This time we could confirm the condition of transformation quantity and stress distribution by enforcing the previously used structure analysis of flex link. And we utilized the reference data to establish important point of section for non destructive test overhaul.

Ultra Precision Machining of the Winston Cone Baffle for Space Observation Camera

The Winston cone baffle was developed for the space observation camera of the MIRIS (Multi-purpose Infrared Imaging System) which is the main payload of STSAT-3 (Science and Technology Satellite). The Winston cone baffle reduces the orbital heat load to the STSAT-3 and is thermally connected to the radiator to cool down. The jig and ultra precision machining jig was designed using a 3D modelling program and analyzed using a computer aided engineering program (ANSYS). The reasons for designing the jig for the baffle were to enhance the stability of the machining and improve the form accuracy of the baffle. The strength, weight and barycentre of the jig are investigated to find the optimized ultra precision machining conditions. To maintain the weight balance of the baffle at high speed rotation, there are lots of holes that can be inserted by heavier bolts. Vibration of the natural diamond bite tool is reduced by using thin copper pipe and urethane silicone. Using this bite tool, we could decrease patterns on the surface of the Winston cone baffle. The results of the simulation using ANSYS show that maximum deformation of the baffle is less than the tolerance limit. Surface roughness of the fabricated Winston cone baffle is machined with the jig and the machining tool is under 5 nm. The Winston cone baffle is plated with gold after being electroless plated with nickel. This baffle is applied to the flight model of the MIRIS.

플라스틱 DVD-Tray의 박막 사출성형을 위한 최적화 설계 Simulation에 관한 연구

사출성형은 다양한 형태의 제품을 대량 생산할 수 있는 플라스틱 성형 공법중의 하나이다. 플라스틱 제품을 만들기 위해서는 고상의 재료를 액상으로 녹인 후 다시 고상으로 굳히는 과정을 거치는 데, 이 과정 중에 많은 문제점들이 발생을 하게 된다. 과거에는 이러한 문제를 해결하기 위해서 성형 후 금형 설계 변경 등의 시행착오적 방법을 사용하였으나, 성형과정에 대한 사출성형 CAE(Computer Aided Engineering)를 적용함으로써, 사전에 문제점을 파악하는 기술이 도입되었다. 플라스틱 제품의 큰 문제점 중 하나가 치수안정성이다. 특히 박막사출성형품은 게이트의 위치, 냉각채널과 온도에 따라서 변형량이 크게 달라진다. 본 연구에서는 현재 Stackmold방식으로 4개의 Cavity에 4개의 Hot-Runner가 설치된 금형을 통해 생산중인 DVD Tray 박막사출제품의 생산 원가 절감을 위해서 Cavity하나에 한 개의 Hot-Runner를 설계하기 위해서 CAE 해석을 통해 게이트의 위치, 냉각채널과 온도에 따라 비교하여 해석해 최적의 제품 설계를 하였다. CAE 해석에는 상업화된 CAE 프로그램인 Moldflow를 사용하였고, 수지는 PC+ABS를 사용하였다. 【Injection molding is one of plastic forming technology which can easily mass-produce plastic parts with various and even complex shape. The technology has lots of difficulties in making a good part due to phase change of material, high applied pressure, and fast melt flow speed in the cavity. To overcome the problems, they had to make trial and error method until the CAE(Computer Aided Engineering) could be a tool for concurrent engineering. In this paper, we investigate the optimal design for a plastic DVD tray part by systematic approach of the commercial CAE program. In design, we should consider two objectives which are both dimensional stability and cost-down. The dimension of the part is crucial because the tray should carry a DVD correctly, but the part is too thin to injection-mold easily. In order to improve the moldability, the mold is designed in the form of stack mold which is a kind of 4 hot runner system. In first, we changed the stack-mold system with one hot-runner to cost down, and decided the optimal position of the gate. After that, we investigate the effect of both the layout of cooling channels and the cooling temperature on the shrinkage of the DVD tray. A optimal simulation approach, the gate design is 2Gate#3 and the layout is Case2 cooling line as the optimal temperature of $70^{\circ}C$ . The Moldflow and PC+ABS are used for the CAE program and material respectively.】

A CAE (computer aided engineering) approach to dynamic whole body modeling--the forces iin the lumbar spine in asymmetrical lifting

Biomechanical models of the human body play an important role in the analysis of the mechanical loading of the musculo-skeletal system. The whole-body model presented in this paper is based on a CAE (Computer Aided Engineering) program that permits the dynamic simulation of complex systems of rigid bodies. The model we developed on this basis consisted of 19 segments and 18 joints. The experimental data are derived from the 3D motion analysis system VICON, which is provided with 5 cameras, a force-plate and a 10-channel EMG recorder. The kinematic data are fed into the simulator after first being processed in a special manner to generate drivers for joint angles. The model was first used to calculate the compression forces generated within the lumbar spine during the asymmetric lifting and putting down of a 15 kg stone. The quasistatic calculation shows a dynamic contribution to the compression forces generated during the lifting of 11%. Increasing or decreasing the inertial moments of the segments by the factor 2 had an effect of less than 1% with the identical movement.

Measurement and Analysis of Polymer Temperature within the Mold in the Cooling Stage of Injection Molding.

The polymer temperature within the mold was measured with a specially designed thermocouple sensor for validating results computed by a cooling analysis program, which is one of the CAE (computer-aided engineering) programs in injection molding. The thermocouple consisted of 0.1mm dia. chromel/alumel elements and a 8mm dia. Teflon rod, which was used to hold the thermoelements at the gapwise center of the cavity and insulate them from each other and from the mold. The thermojunction was exposed and immersed into the cavity far enough to avoid thermal conduction error. A one-dimensional unsteady heat conductive equation was solved by the finite difference method with consideration of the latent heat and the contact heat transfer between the polymer and mold. Computed cooling curves were compared with experimental ones for various cavity thicknesses and two materials, polystyrene and polypropylene. The predicted minimum cooling times, which were defined as the necessary time for the polymer melt to be cooled to the solidification temperature at the center of the thickness, were in good agreement with the experimental ones for polystyrene, but were about 1.3 times for polypropylene.

Technical Notes: Solid Model Geometry by Screen Digitizing Images

Computer-aided-engineering (CAE) approaches to modeling of biological objects are limited due to the extensive amount of manually entered geometric data needed to accurately represent the object. A solution to this problem combines a CAE program with cursor position data entry, a terminal emulator with graphic overlay capability, and image analysis software. This combination aided the developing of the geometry for a finite element model of a whole wheat kernel from 35 mm slides of serial cross-sections. The geometry was defined in less time than conventional methods and has great potential as a data entry aid in developing models of agricultural and biological materials.

A unified database for data exchange in electromagnetic field computation

A unified database for data exchange among field computation and CAE (computer-aided engineering) programs is presented. The integrated system is demonstrated using there established field computation programs, Flux3d, Phi3d, and Trifou, the solid modeller Geomood, and the mesh generator Supertab. First, the motivation for interfacing these programs is explained. Next, various interfacing mechanisms are examined. A unified database for data exchange is then developed, and finally an example of data transfer using the unified database is illustrated. Initial results are very encouraging and showed the feasibility of program integration and data exchange through a database. >