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With times of tensile tests, the tensile behavior of a kind of stainless steel at room temperature was determined. According to the results of tensile tests, some parameters of mechanical properties of the stainless steel can be obtained. Fatigue crack expansion of COD stainless steel specimens at room temperature can be simulated with the finite element software extensions.

Introduces the working principle of capping machine, the defects caused by the deficiency of the actual production situation of working medium pressure covermachine and its compensation spring, redesign compensation spring, and the design, the factors should be considered in a simple discussion.

Study of grain size and lamellar spacing on fatigue crack propagation resistance in TiAl alloy has been done. The effects have been analyzed specifically. Meanwhile, the influence has been verified with some fatigue crack propagation experimental results and Paris formula. The experimental results confirmed that the grain size and lamellar spacing have significant effect on fatigue crack growth resistance. According to the Paris formula, the specific values of the constants in the formula were calculated.

Study on the Ti-43Al-9V-0.3Y alloys forged microstructure, which added a large amount of β phase stable element. The influence on the mechanical properties and synusia cluster refinement about β phase is analyzed. The test of material static tensile at 700 °C and room temperature is conducted. The results show that the V elements urges the grain size α2 and β phase formation, β phase can inhibit α grain growth effectively. At the same time, its deformation ability can increase the high temperature plastic of the material. Experiments show that the main form of alloy tensile fracture at room temperature was intergranular fracture. Hole proliferation and communicated with each other through layers of crack is the main characteristics of high temperature tensile fracture of the alloy.

Experimental investigations of fracture toughness for a TiAl-based γ-alloy were performed at different temperatures. The temperature effect on fatigue crack growth behavior is evaluated, the formula describing its rate in range to II (stable propagation) was derived, as well as specific values of equation constants were obtained on the basis of experimental results. Tests were conducted in vacuum at 25, 750, and 850°C. The experimental results demonstrate that temperature exerts great influence on fatigue crack growth rates. With an increase in temperature up to 750°C, the growth rate of such cracks increases, after reaching this temperature, the brittle-ductile transition of a TiAl-based alloy is taking place. A similar relationship is also observed for conventional alloys.

Based on the theory of finite element and modal analysis theory, analysis of static and dynamic characteristics of the lathe bed has been done. The static displacement contours and mode natural frequency and displacement contours have been given to realize the structure optimization of lathe bed of high-speed horizontal machining center. It is shown that the bed has good static stiffness and natural frequency and the deformation of lathe bed mainly occurred in the tray conversion mechanism and the cutter location. The deformation of processing work area is small and has certain light weight space, which lay the foundation for the lightweight design of the bed.

Study on tensile fracture behavior of TiAl alloy by means of the macro fracture theory and micro dislocation block theory. A quantitative analysis method of micro crack nucleation and crack mechanism for TiAl alloy is performed with the help of the dislocation distribution model, and is based on the strain energy density theory and criterion, a crack criterion of TiAl alloy instability is established. The experimental results confirmed that the dislocation model and S criterion on tensile fracture behavior of TiAl alloys are effective.

Based on the fatigue crack propagation experiments did by A.-L. Gloanec et al., the fatigue crack propagation rates of TiAl alloy of two processing routes, namely casting and PM, and stress ratios had been tested, in order to find out the effects of microstructure and stress ratio. An improved fatigue crack propagation formula for region Ⅱ (the expansion region) was derived according to Paris formula. The specific values of the constants in the formula were calculated. Fatigue crack propagation resistance of nearly fully lamellar microstructure is superior to that of equiaxed γ grain. The experimental results present that both microstructure and stress ratio has a significant influence on fatigue crack growth rate.

With the Synchronous Dual Ball Screw Feeding System used in a Milling-Turning compound machining center as the research object. For study the ball screw vibration modal, which using Lagrange established the dynamics equation and using the Lizs series expansion analyzing its various order modal coupling characteristics. Meanwhile using the ANSYS analysis to get the first three order vibration mode diagram and calculate the frequency corresponding to the critical speed for each rank. Through the analysis found that the screw pitch determine the modal coupling axial and corner, the workbench position and load quality changes, the screw vibration frequency also changes. Provide theoretical analysis for the analysis of dynamic characteristics of the next step.

Based on the experiments did by B.K.Parida and T.Nicholas [1], the fatigue crack propagation rate of TiAl alloy under different stress ratios had been tested in order to find out the role of stress ratio and to derive an improved fatigue crack propagation formula for region II(the expansion region) according to Paris formula and to calculate the specific values of the constants in the formula. The experimental results reveal that stress ratio has a significant influence on fatigue crack growth rate.

For the shorting of fracture mechanism from the point of high temperature condition, so a new method of illustration, which is carried out under the condition of high temperature, for fracture mechanism will be adopted in this paper. And a more accuracy and more understandability result can be got by this new method. Besides, the performance of TiAl alloys can be improved by making grains refined to decrease the slip plane spacing, which can be got from the mechanics analysis.