Papers by Keyword: Deformation

Abstract: Microstructural changes due to isothermal heat treatment in the bent regions of cold folded nickel alloy (Ni200), mild steel, and Titanium (Ti6-4) sheet samples, followed by the EBSD (electron back-scattered diffraction) technique are reported. Large strain gradients that vary from being tensile to compressive exist in the bent regions and have been used to study their influence on recovery and recystallisation processes. Isothermal heat treatment at 600°C in the Ni200 and steel sheets results in recrystallisation process to start in regions with the highest strains and progresses towards the centre of folded regions. Grain growth was observed to be dependent on both the sign of the strain and its level. Generally larger grain sizes were associated with tensile strains in both Ni200 and steel. Abnormal grain growth occurred after prolonged heat treatment in the Ni200 sample in regions with low levels of tensile strains found in the middle of the sheet thickness. Although complete recrystallisation was not observed in the steel sample significantly large grains formed in regions with low strain levels. Only recovery processes were observed in the Ti6-4 samples. Some twinning was also observed in Ti6-4 that was confined in the regions with compressive strains. Crystallographic textural changes were observed during this study and will be reported in future publications.

Abstract: The Dutta-Sellars equations for predicting recrystallisation and precipitation in microalloyed steels have been assessed for accuracy over a range of strain levels (0.15 to 0.45) during hot deformation (975-1075 °C) of a homogenised 0.045 wt % Nb steel. It has been found that the model predicts the deformation state well at a strain of 0.3 whereas at both lower and higher strains i.e. 0.15 and 0.45, the agreement is less good. The differences between prediction and experimental measurement have been related to solute drag and precipitate potential of Nb.

Abstract: The sheet manufacturing process, which involves various solid-state transformations such as phase transformations, plastic deformation and thermally activated recovery processes, determines the texture of steel and aluminium sheet. The conventional process of flat rolling and annealing only offers limited degrees of freedom to modify the texture of the final product. After annealing a {111} recrystallization fibre in BCC alloys and a cube dominated recrystallization texture in FCC metals is commonly obtained. Many applications, however, require other texture components than the ones achievable by conventional processing. In the present paper it is shown that by asymmetric rolling of a Si-alloyed ultra-low carbon steel a texture can be obtained with increased intensity on the {001} fibre, which is of interest for magnetic applications. Also in aluminium alloys the strong cube annealing texture can be drastically modified by the process of asymmetric rolling. It is argued that by observing the proper rolling and annealing conditions a recrystallization texture with improved normal and planar anisotropy of the mechanical properties may be produced.

Abstract: The deformation of the prestress frame of open-die forging hydraulic press is studied in the paper. Firstly, the computing formula of true prestressing force of frame is deduced, and then the finite element model of prestress frame is established. With the model, the deformation of prestress frame is studied when the press works under different operating modes including upsetting, elongating and saddle forging and the effect of different operating modes on the deformation are revealed. The main achievements include: The true prestressing force of frame can be gained with nominal prestressing force, section area and working length of tension rods, section area and length of columns. Under prestress, the stress of the field of up beam and down beam acted by the axial force of tension rods and columns is bigger, that of the other field is very small. Under working loads, up beam and down beam tend to open out, tension rods and columns tend to bend in, and the bending effect cause the stress of inner field of tension rods bigger than that of outer field and the stress of inner field of columns smaller than that of outer field. The deformation of down beam under saddle forging is different with that under upsetting and elongating. The stress of center field of down beam under upsetting and elongating is higher and that of front and back field of down beam under upsetting is higher. The main achievements of the study are useful to design the prestress frame of open-die forging hydraulic press and the research method can be used to study the prestress frame of other equipments.

Abstract: This paper mainly solved the 3D modeling and force analysis of φ320 mm hydraulic support column. According to the hydraulic support column standard, computer simulation was manipulated forφ320mm column by not only 1.5 times rated axis load strength analysis but also 1.1 times rated load and eccentric 30mm buckling analysis. Through analysis and simulation tests，not only the distribution and deformation ofφ320mm column but also the stress distribution and simulation conditions were got about column. Thus, theoretical basis could be provided for the design of column.

Abstract: The research use an impact test enginery, choose T10 steel samples, and do a low stress repeated impact collisions experiment. By comparing two kinds of different heat treatment of T10 steel, analyze and research its macro plastic deformation phenomena and plastic accumulation law in low stress repeated collision impact load, and observe its hardness change by hardness microscopicand and its metallographic structure by metallographic microscope to discuss its deformation causes.

Abstract: This study describes a method to simulate cloth texture deformation using a neural network model. The cloth texture may be represented by its texture colors, positions and its topological structures. In addition, the relationship between the texture colors can be deduced based on the smooth texture and the two and three dimensional texture deformation are correspondingly concerned. A multilayered single direction neural network model is adopted to numerically represent the cloth texture for the purpose of speeding up the simulation. The color values of the points on the cloth deformed curved surface can be calculated with such neural network model. The experimental results show that such method is efficient and executable for the regularized texture deformation.

Abstract: Open-front press is one of the dominating equipment for punch forming. Body frame is the primary loadbearing part of this machine, and its rigidity and intensity have great influence on the working performance. In order to optimize the structure of body frame and shorten the product development cycle, finite element analysis, which is an effective technique in CAE, is used to investigate the body frame’s deformation and stress distribution in the presented work. By taking JC21-160, a representative type of open-front press, as the analysis object, the whole procedures of this work, such as modeling, meshing, loading, constraint handling and the solving, have been discussed explicitly. The analytical method and result will conduce to improve the structure design of this kind of machine and the similar devices.

Abstract: Support Vector Machine (SVM) is a new pattern recognition method developed in recent years on the foundation of statistical learning theory. It wins popularity due to many attractive features and emphatically performance in the fields of nonlinear and high dimensional pattern recognition. Due to the complexity of the deep excavation, deformation prediction problem has not been a good solution. In the paper the support vector machine model was proposed to predict the deep excavation deformation. On the basis of deep excavation displacement data measured with real time series, the model of deep excavation displacement with time was built by SVM. Typical deformation data of deep excavation is used as learning and test samples. Comparison analysis is made between calculated values generated by SVM method and observed values. The result shows this method is feasible and effective.

Abstract: Based on ANSYS software and combined with the theory trends on stern shaft seal performance, the steady-state thermal structure coupling and transient thermal structure coupling analysis of stern shaft mechanical seal had been carried on. It showed that the transient thermal structure coupling analysis was more close to the actual condition of stern shaft seal. The result of transient state analysis indicated the thermal-mechanical effect on seal face during starting, and showed that the contact area was decreased especially the temperture rise rapidly inside of the seal.