The reported work has developed a methodology of printing and curing continuous fiber‐reinforced thermosetting polymer composites (CFRTPCs) with excellent mechanical properties at low temperatures. First, to print and cure CFRTPCs at low temperatures, a thermosetting polymer system was proposed, consisting of phenol based epoxy resin and curing agent (F‐44/2E4MZ). The rheological properties of the polymer system were analyzed to determine a reasonable printing temperature. Second, the non‐linear Vyazovkin integral method was applied to establish the model‐free kinetics (MFK) of the resin system. MFK can predict the curing degree curves at the characteristic temperatures obtained by extrapolation. Reasonable curing process parameters were determined by analyzing the predicted curing degree curves. Then, CFRTPC samples were prepared with the low‐temperature 3D printing process and the low‐temperature curing process, and the fiber content was found to be 53 wt.%. At last, the mechanical property measurements revealed that the tensile and flexural strengths were 1012 MPa and 929 MPa, respectively. This work can further expand the potential applications of 3D printed CFRTPCs in aerospace and defense industries which require high mechanical properties and temperature safety simultaneously.

A significant source of noise and vibration in high speed machine tool spindle is bearing induced vibration, which is caused by geometrical characteristics and interactions between rolling members with surface irregularities. In this paper, analytical approach was proposed to calculate the bearing internal load distribution of spindle, with consideration of the operating conditions. The influences of operating conditions to internal load distribution, contact angles were analyzed. Furthermore, the estimation of power spectral density (PSD) method was used to analyze determination of bearing frequencies. The bearing preload of machine tool spindle was estimated according to the change of ball bearing frequencies. Experiments were carried out in a spindle bearing test rig to verify the validity of the presented analytical method. The method described in this paper can achieve the estimation for bearing preload of machine tool spindle.

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Electrical properties, metallurgical properties and their relationship of PtSix/GaAs formed by sputter deposition and TiSix/GaAs formed by e-gun multilayer evaporation have been studied. It has been found that TiSix/GaAs contacts exhibit excellent Schottky electrical propcrties and good metallurgical stability after RTA (975°C , 12 sec) but some interface unstability and degradation of electrical properties after conventional FA (800°C ,20 min). The electrical and metallurgical properties of PtSix/GaAs contacts begin to degrate after annealed at 500°C.