Radiation Hardness Property of Ultra-Fast 3D-Trench Electrode Silicon Detector on N-Type Substrate

The radiation fluence of high luminosity LHC (HL-LHC) is predicted up to 1 × 1016 1 MeV neq/cm2 in the ATLAS and CMS experiments for the pixel detectors at the innermost layers. The increased radiation leads to the degradation of the detector properties, such as increased leakage current and full depletion voltage, and reduced signals and charge collection efficiency, which means it is necessary to develop the radiation hard semiconductor devices for very high luminosity colliders. In our previous study about ultra-fast 3D-trench electrode silicon detectors, through induced transient current simulation with different minimum ionizing particle (MIP) hitting positions, the ultra-fast response times ranging from 30 ps to 140 ps were verified. In this work, the full depletion voltage, breakdown voltage, leakage current, capacitance, weighting field and MIP induced transient current (signal) of the detector after radiation at different fluences will be simulated and calculated with professional software, namely the finite-element Technology Computer-Aided Design (TCAD) software frameworks. From analysis of the simulation results, one can predict the performance of the detector in heavy radiation environment. The fabrication of pixel detectors will be carried out in CMOS process platform of IMECAS based on ultra-pure high resistivity (up to 104 ohm·cm) silicon material.

Effects of different friction coefficients on input torque distribution in the bolt tightening process based on the energy method

Bolted joints are one of the most common fastening methods in engineering applications. To meet the requirements of structural parts, the torque method is often used for controlling the bolted joint performance. However, only a few investigations have been carried out on the conversion efficiency of bolt torque to the tensile force, leading to uncertainty and potential safety hazards during the bolt tightening. In order to study the input torque distribution and overcome problems caused by the Motosh method and experimental investigations, a new energy-based torque distribution model is established in the present study. In the proposed model, numerous affecting parameters, including the effective bearing radius, effective thread contact radius, spiral angle, and connector deformation are considered. Then a parameterized thread mesh model using finite element technology is proposed to analyze the influence of different bolt friction coefficients on the bolt tightening process. Based on 16 types of tightening analyses, it is concluded that as bolt friction coefficient increases, the corresponding torque conversion rate decreases from 14.45% to 7.89%. Compared with the Motosh method, the torque conversion rate obtained by the proposed method is relatively large, which makes the actual pre-tightening force larger than the design value. However, there is still a possibility of bolt failure.

Investigation of Mechanical Numerical Simulation and Expansion Experiment of Expandable Liner Hanger in Oil and Gas Completion

The expansion experiment of the expansion liner hanger is a one-time failure process, so in order to save cost, the finite element technology needs to be used to simulate the expansion experiment. Obtaining the mechanical parameters of the expansion liner hanger can effectively optimize the size of the expansion liner hanger structure and guide the expansion completion. Firstly, main structure and principle of expandable liner hanger were introduced. Secondly, mechanical equilibrium equations of the expandable process were established to obtain pressure of the expandable fluid, and pressure of the expandable fluid is obtained. Thirdly, finite element (FE) simulation mechanical model of the expansion of the Ø244.5 mm × Ø177.8 mm expandable liner hanger was established to analyze the hang mechanism and the change rule of mechanical parameters during the expansion. The FE results have shown that radial displacement and residual stress of the inner wall of hanger varied in 5 cycles, and the expansion ratio of the expandable tube was 7.4% during the expansion. The expansion force did not change stably but gradually increased in stages. And the hydraulic pressure required for the expandable cone to continuously move down was 18 MPa. According to the contact stress generated on five rubber cylinders and the contact stress generated on five metal collars, the total hang force has been calculated, which exceeds 1000 kN and meets the design requirements. Lastly, the expansion test results have shown that expansion pressure was 19 MPa, and the expansion rate was 7.1%. The mechanical analysis results of the expandable liner hanger were in good agreement with the experiment results in this study, which provide important mechanical parameters for well completion with expandable liner hanger.

Experimental and simulated research on the ballistic performance of Ti/Al3Ti laminate composites

The metal-intermetallic laminate composite Ti/Al3Ti can be used as protective armor in aerospace and military applications, due to its low density, high strength, and superior impact-resistant performance. The ballistic performance of the laminate composite was studied by ballistic testing and finite element technology. The failure modes, such as radical cracks, layer delamination, and plastic deformation, have been found after the ballistic test, and the specific energy absorption was used to evaluate the ballistic capacity of the material. The finite element model of the Ti/Al3Ti impacted by the projectile was established by considering the interface, which was simulated by the solid elements with zero thickness. The simulation results demonstrate the failure process of the interface during penetration. The interfacial failure allowed for layer detachment with its labor layers. The simulation results agree well with that of the experiment, and the practicality and credibility of the model is verified.