For new medical β titanium implants, the surface micro texture processing technology is a difficult problem. To solve this problem, a new method of ultrasonic elliptical vibration cutting (UEVC) is adopted in this paper. The mechanism of material removal in ultrasonic elliptical vibration cutting is explored for different cutting paths. By means of simulation and experimentation, the material removal mechanism of ultrasonic elliptical vibration cutting medical β titanium alloy is revealed with respect to the aspects of cutting deformation, stress distribution, force and thermal variation, and chip formation mechanism. The results show that: (1) The cutting temperature and cutting force in the UEVC process obey the law of periodic change, and the maximum point of cutting force appears ahead of the maximum point of cutting temperature. (2) The material removal process of UEVC is a “press–shear–pull” composite cutting process. The tool squeezes the material to form the chips. Under the action of high temperature, the material is removed by adiabatic shear. (3) The difference of UEVC paths will affect the removal mode of materials and form different surface morphology. (4) For different cutting paths, compressive stress is distributed at the lowest point of the machining pit, and tensile stress is distributed at the protrusion position.

In this paper, ABAQUS finite element simulation software was used to establish a more reliable three-dimensional milling titanium alloy Ti6Al4V finite element simulation model. This model sets up important links such as the material constitutive model, the tool-chip contact friction model, and the chip separation criterion. And the accuracy of the model is verified by experiments. Based on this model, orthogonal experiment was used to explore the effects of axial cutting depth, tool speed and feed speed on the milling force. And the morphology of the chip and the surface morphology of the machined workpiece were investigated. The results show that the influence of cutting parameters on milling force from high to low is as follows: axial cutting depth > tool speed > feed rate. The change of cutting parameters has different influence on milling force in all directions, and has the largest influence on milling force in X direction.

The thermal shock load has an important effect on the stability of thin-walled blades under high-speed operation of aircraft engines. According to the actual working conditions, the linear interpolation distribution of blade temperature is obtained by the numerical fitting method. A thermal buckling model is built to obtain the linear and nonlinear modal response of the blade through the finite element method. The results show that the blade stiffness changes under the influence of thermal buckling and the obvious torsional deformations are produced along the radial direction of the blade. Meanwhile, the largest deformation of about 1.3 mm and stress of 81 Mpa occurs on the blade tip for both the linear and nonlinear response. The buckling stress distribution and critical load factor of thermal buckling are also calculated, consistent with the rubbing part of blade. The changing radial length is the main reason for the distance reduction between the blade and casing, causing more probability of friction impact. Therefore, reasonable local thermal buckling technology is helpful to improve the design level of thermal-shock loaded blades.

In order to improve the surface quality and wear resistance of Mn13, increase its service life. Mn13 was strengthened by ultrasonic surface rolling (USRP). The effects of ultrasonic rolling parameters (rolling pressure and rolling times) on surface roughness and surface hardness were studied. A set of surface roughness instrument and micro Vickers hardness instrument were used to analyze the samples Moreover, the surface quality of Mn13 before and after ultrasonic rolling was compared and analyzed. The results show that increasing the rolling times can reduce the surface roughness significantly, but excessive rolling times are liable to produce microcracks. Increasing the static pressure, the surface hardness and the depth of strengthening layer will increase. And the roughness can be reduced below 0.06 μm after ultrasonic rolling. The surface hardness can reach up to 741 HV, and the depth of strengthening layer is 700 μm.

The mechanical properties of anisotropic materials are generally characterized based on the orthotropy or transverse isotropy. However, the two-dimensional plane stress problems cannot comprehensively characterize the anisotropy of materials. In this study, based on the theory of elasticity and the transformation of the three-dimensional space coordinate system, combined with the projection relationship of the Cauchy stress tensor of an arbitrary section, the transformation relationship of the elastic modulus, shear modulus, and stress–strain between the orthogonal and load coordinate systems are obtained. The orthotropic Johnson-Cook (JC) constitutive model of AA7050-T7451 aluminum alloy is modified by fitting, and the constitutive relationship at any spatial angle is theoretically calculated by combining the obtained spatial coordinate transformation matrix. The generated spatial constitutive model is verified and modified through experiments. The results demonstrate that the theoretical mechanical properties and the modified spatial constitutive model can accurately reflect the effect of the spatial angle on the material stress distribution.