Materials Science Forum Vols. 532-533

Abstract: It is very important to establish the control model for deformation path during the process of metal forming. Using the techniques of Artificial Neural Network(ANN) and numerical simulation, a new approach controlling deformation path based on the identification of material parameter is proposed. In this approach, the identification of material parameter value m and the control of deformation path proceed one by one in each loading stage. The identification of material parameter is finished by ANN using the experimental strain increments, loading increments and material stresses, after that, we can get loading increments for the next deformation stage by the ANN trained by material stresses, objective strain increments and the identified value m. By tension and torsion test of thin walled tube on MTS testing machine, the experimental strain path was obtained and compared with objective one. The results of this comparison validate the proposed approach for the deformation path control.

Abstract: A new approach is proposed to model the milling force based on the cutting force shape characteristics in end milling. The relationship between the cutting force shape characteristics and the cutting depths is analyzed and milling forces are classified into 10 types according to the combination of cutting depths. Further, force indices are extracted and then the real cutting depths are detected based on the changes of force curve characteristics via the force indices in end milling process. Then, bring forward a method of modeling cutting force based on the different types, and the use of real cutting depth makes the model to be more accurately. More important, experiments designed on the classification of milling forces strengthen the pertinence, and makes the experiment data more reliable. The approach is validated through experiments on aluminum alloy 7050-T7451.

Abstract: Domain knowledge representation is various and domain-concerned. The aircraft assembly process planning (A2P2) is a special domain, a lot of things should be taken into account, and the knowledge representation of A2P2 is complicated. It is focused on the knowledge representation of A2P2 in this paper. Based-on case, the framework of A2P2 knowledge is presented. The main considerations of A2P2 are analyzed, the transformation and reassembly of native A2P2 knowledge is studied, the features of A2P2 is acquired, and the formalizable framework of A2P2 is proposed. With BNF, a formal description of A2P2 knowledge is given.

Abstract: Ti-6.5Al-2Zr-1Mo-1V is a near alpha titanium alloy strengthened by solid solution with Al and other components. In this study, a series of experiments on tool wear and surface integrity in high speed milling (HSM) of this alloy were carried out. The tool lives under different cutting speeds were studied and the corresponding empirical equation of tool life was derived. Additionally, the wear mechanism of cutting tools was also discussed. Finally, surface integrity, including surface roughness, metallograph, work hardening and residual stresses, were examined and analysed. The result shows that good surface quality of workpiece could be obtained in HSM of the alloy.

Abstract: A micro-meso-macro finite element approach has been developed for simulating the macro-scale damage coupled deformation in a particulate polymer composite (PPC) based structure under tension. A damage model for the PPC structure was developed to define the debonding damage behavior of the structure. The computational results determined in our previous studies by using finite element meso-cell modeling technique were used as the input parameters of the damage model and definition of the constitutive behavior of PPC. A user-defined subroutine VUMAT describing the damage-coupled constitutive behaviour of PPC for defining the material properties of the finite elements for the structure was then built and incorporated into the ABAQUS finite element code. A case example has been given to demonstrate the proposed approach. The macroscale damage process in the simulated component was found to be reasonable.

Abstract: In this study, the ability of Selective Laser Sintering (SLS) Technology for production of wind tunnel testing models are evaluated. It has been undertaken to determine the suitability of the Model constructed with SLS method in subsonic and transonic wind tunnel testing. Two models were evaluated in this study. The first model was fabricated from aluminum 5086-H32 by a CNC machining technique. The other model had the same section but was fabricated by the selective laser sintering (SLS) process. Aerodynamic characteristics and times as well as costs of both models were measured in 0.3 to 1.2 Mach and the results were compared. The longitudinal aerodynamic data and the normal force data obtained from SLS model showed good agreement with data obtained from the aluminum model. The greatest difference in the aerodynamic data between two models is the total axial force. The time and the cost of production are considerably reduced with use of SLS model.

Abstract: The objective of the present work was to study the modification of the microstructure of hot-work tool steels X40CrMoV5-1 and X38CrMoV5-3 during the surface modifying by means of laser technology. This treatment aims to harden and alloy the steel surface which had been previously coated with tungsten carbide (WC) and were introduced using the rotor conveyer to improve the properties of the surface layer. The fine grained, dendritic structure occurs in the remelted and alloyed zone with the crystallization direction connected with the dynamical heat abstraction from the laser beam influenced zone. The fine grained martensite structure is responsible for the hardness increase of the alloyed layer.

Abstract: The CAM operation which generates a process plan and NC-data for mold machining plays an important role in mold manufacturing because it quite affects down stream processes such as NC machining, polishing, and assembly operation. This study proposes a supporting system which facilitates non-experts to perform the CAM operation easily and to select the high-quality NC-data which can increase machining productivity. It also designs and implements the support system in accordance with a CAM operation scenario. To check the usability of the support system developed, this study applies it to some practical examples of molding dies.

Abstract: This paper reports a simple and novel procedure for mold insert of microlens array. The micro injection molding (MIM) and micro injection-compression molding (MICM) are used to replicate the microlens array. The 200×200 arrays of molded microlens, with a diameter of 150 $m, a pitch of 200 $m and a sag height of 11.236 $m have been successfully fabricated. The average surface roughness of the Ni mold insert is 6.916 nm. The average surface roughness of the molded microlens array is 4.608 nm for MIM and 4.555 nm for MICM. The complete fabrication process of mold insert is executed at room temperature and low pressure for this paper.

Abstract: Error correction of optical complex surfaces in computer-controlled optical surfacing (CCOS) is primary important. This paper discusses some methods, i.e. Fourier transform method, Wiener filtering method, directive method and iterative method, for calculating dwell time or relative pressure in the CCOS for error-correcting, which are enlightened from the digital image processing techniques. However, these error correction methods are different from the image processing because they are not a subject of solving the causal signal but a problem of an iterative process. The simulation results show that the Wiener filtering method is good and reliable when the correlative parameters in the fabrication are kept consistent.