摘要:

Microcellular polymer foams exhibit greatly improved mechanical properties compared to standard foams due to the formers' small bubble size. Typical microcellular foams have bubbles with diameters on the order of 10 microns and volume reductions of 30 to 40%. The presence of these bubbles acts to increase the impact strength of a microfoamed structure to six or seven times that of solid parts of the same linear dimensions due to crack blunting and increased craze initiation in the cell walls.

ISSN:0884-2558    

DOI:10.1080/10426918608953169

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

As America refocuses its attention on the factory, design and manufacturing engineers must work together closely to design the appropriate products, and matching production process in a team effort. By building off the designer's CAE tools that predict product performance, the manufacturing engineer is today able to simulate the proposed production process. Process simulations for the following manufacturing processes are available or being developed:

ISSN:0884-2558    

DOI:10.1080/10426918608953170

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

This paper presents the solutions to the stochastic differential equations which mathematically represent the machine tool workpiece system in BTA deep hole machining. The stochastic differential equations are derived assuming an appropriate model for the tool-workpiece interaction, and the machine tool work-piece system. The solutions to the non-parametric inhomogeneous differential equations are obtained using the Fokker-Planck equations. Based on these solutions, the true motion of the tool tip has been described using the maximum, average, and minimum error curves. Also, using the statistical description of the true motion, equations are derived which mathematically describe the CLA and RMS value of the surface produced. Based on these results, it is seen that the CLA and RMS value of the given surface vary 1n a given band depending upon certain machining paraj meters. The measurement of the surface texture of the specimens shows that the experimentally measured CLA values agree reasonably well with the theoretically predicted values.

ISSN:0884-2558    

DOI:10.1080/10426918608953171

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

A comprehensive technique is described for performing the simulation of the solidification of foundry castings. A finite element method (FEM) mesh is produced for the pattern of the part, using geometric modeling techniques. Results are presented to demonstrate selection rules for the mesh size. The size of the heat transfer problem is reduced by replacing the FEM mesh in the mold material by appropriate boundary conditions on the surface of the casting. The boundary conditions are found automatically by a program which relates local surface curvature on the part to a pre-calculated library of solutions. Methods for ensuring that all of the latent heat of fusion is included are presented, and comparisons are made between different solution methods.

ISSN:0884-2558    

DOI:10.1080/10426918608953172

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

This paper presents a general method for the design, analysis and optimization of mechanical press linkages. In order to use the method, the linkage type must be identified, and geometrically proportioned to approximately satisfy the mecnanical requirements. Next, system equations must be derived for that linkage, which describe input/output relationships for displacement and force. Upon completing these two steps (which typically must be done in any case), the method can then be employed to optimize that linkage for the particular application.

ISSN:0884-2558    

DOI:10.1080/10426918608953173

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Axisymmetric forging of powdered-metal preforms was analyzed by the finite element method neglecting the effect of temperature on deformation. A remeshing program based on the area-weighted-average technique was developed and tested by simulating forging of the flange-hub shape. Then the analysis was performed for forging of a pulley blank. The detailed deformation characteristics for the different preform shapes under the two frictional conditions were obtained. A comparison between the prediction and the experiment regarding proper preform design to forge defect-free pulley blank demonstrates that the finite element analysis is useful for further developments in preform design in powdered-metal forging.

ISSN:0884-2558    

DOI:10.1080/10426918608953174

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

In the manufacturing of heavy forgings, one of the most important aspects of the process is the consolidation of internal voids which result from the ingotmaking process. To insure a good quality finished product, these voids must be closed by proper choice of forging practices - including such factors as die geometry* amount of reduction, reduction speed, and workpiece temperature. This paper focuses on the first two of these factors and reports the results of a study on the effects of die width and reduction on the closing of a void.

ISSN:0884-2558    

DOI:10.1080/10426918608953175

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Powder metallurgy is a source of new and viable near or net shape manufacturing processes, with compelling economic and technical advantages over conventional ingot metallurgy practice. Selected commercial methods are considered, namely pressing and sintering, injection molding, powder preform working and direct powder consolidation. Particular attention is directed to the prevailing state of stress, temperature and time in each mode, since these dictate densification mechanism(s), and hence microstructure and properties.

ISSN:0884-2558    

DOI:10.1080/10426918608953176

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Rao and Chaturvedi [18] had presented an analysis to consider the effect of thickness on the forming limit diagrams through a correction in the MK model taking into consideration the influence of the triaxial stress state in the neck. This model predicted results closely matching the experimental values for Aluminium which is not sensitive to strain rate. This paper presents a new model for predicting forming limits for strain rate sensitive materials relying on the above work and the approach of Marciniak. Kuczynski and Pokara [13]. The results obtained are found to be in close agreement with experimental values (Pig. 4). The model has also been used to analyse the influence of various material property parameters and thickness on forming limits and these are also found to be in good agreement with reported experimental results. The model has also been extended to predict forming limits under a two stage strain path and the results have been compared with the experimental results of Ishigaki [8] (Figs.11 to 14).

ISSN:0884-2558    

DOI:10.1080/10426918608953177

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

A computer model is developed to simulate the electro-magnetic and the heat-transfer behaviors of the taper heating process. The computer-aided tool can provide the necessary information for design and operation of induction furnaces for taper heating required for isothermal extrusion. A feasibility study of two induction furnace designs is presented. Computer results indicate that the three-zone type furnace can provide the desired taper temperature profiles for the aluminum and the titanium alloys considered. Applications of the computer tool to other types of induction heaters are also discussed.

ISSN:0884-2558    

DOI:10.1080/10426918608953178

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor