The study of measuring technology on the dynamic mechanical properties of welded joint with high strainrate

In this paper, to meet the needs of studying work of dynamic mechanical properties of welded joint, the dynamic mechanical properties of welded joint were measured by means of SHPB(Split Hopkinson Pressure Bar).The dynamic mechanical property's curves of every part of welded joint were obtained. For studying the dynamic behavior of mechanical heterogeneity of welded joint, important data were offered. The method of test creates a new way of studying dynamic mechanical properties of welded joint.

Electrodynamic Tethered Deorbit System Dynamics and Performance Analysis

Electrodynamic tethered deorbit technology is a novel way to remove abandoned spacecrafts like upper stages or unusable satellites. This paper investigates and analyses the deorbit performance and mission applicability of the electrodynamic tethered system. To do so, the electrodynamic tethered deorbit dynamics with multi-perturbation is firstly formulated, where the Earth magnetic field, the atmospheric drag, and the Earth oblateness effect are considered. Then, the key system parameters, including payload mass, tether length and tether type, are analyzed by numerical simulations to investigate their influences on the deorbit performance and to give the setting principles for choosing system parameters. Based on this and given an appropriate group of system parameters, numerical simulations are undertaken to study the impact of the mission parameters, including orbit height and orbit inclination, and thus to investigate the mission applicability of the electrodynamic tethered deorbit technology.

A Study on Technological Dynamics in Structural Health Monitoring Using Intelligent Fault Diagnosis Techniques:A Patent-Based Approach

The performance and reliability of structural components are greatly influenced by the presence of any abnormality in them.To this purpose,structural health monitoring(SHM)is recognized as a necessary tool to ensure the safety precautions and efficiency of both mechanical and civil infrastructures.Till now,most of the previous work has emphasized the functioning of several SHM techniques and systematic changes in SHM execution.However,there exist insufficient data in the literature regarding the patent-based technological developments in the SHM research domain which might be a useful source of detailed information for worldwide research institutes.To address this research gap,a method based on the Co-Operative Patent Classification(CPC)codes is proposed in the current study.The proposed method includes the patent analysis of SHM in terms of its global publication trend and technology-based applications.This analysis is performed using patent database search tools,namely,IncoPat and Espacenet.The period ranging from 2005 to 2019 is selected to retrieve the required patent documents.A new approach termed as Patents’value is utilized to investigate the technological impact of a patent in the form of forward citations,technical stability,and scope of protection.The identification of emerging SHM techniques and forecasting of vacant technology is also part of current research work.The research results have revealed the increasing trend in the number of published patents each year related to various SHM technologies.In this regard,China,the United States,and South Korea are notified as to the major depositor countries,respectively.Hence,mapping of patent data in this research is an effort to illustrate the effectiveness of the proposed method to demonstrate the development trends and dynamic inventions over the time in SHM research domain to achieve the optimal damage inspections of various mechanical components.

Molecular Dynamics Simulation on Hydrogen Ion Implantation Process in Smart-Cut Technology

The hydrogen ion implantation process in Smart-Cut technology is investigated in the present paper using molecular dynamics（MD） simulations.This work focuses on the effects of the implantation energy,dose of hydrogen ions and implantation temperature on the distribution of hydrogen ions and defect rate induced by ion implantation.Numerical analysis shows that implanted hydrogen ions follow an approximate Gaussian distribution which mainly depends on the implantation energy and is independent of the hydrogen ion dose and implantation temperature.By introducing a new parameter of defect rate,the influence of the processing parameters on defect rate is also quantitatively examined.

Aeroacoustic and aerodynamic optimization of propeller blades

It is of great significance to develop a high-efficiency and low-noise propeller optimization method for new-generation propeller aircraft design.Coupled with free form deformation method,dynamic mesh interpolation technology,optimization algorithm,surrogate model,aerodynamic calculation and aeroacoustic prediction model module,the integrated aerodynamic and aeroacoustic design method of propeller is built.The optimization design for the six-blade propeller is carried out.The non-reduction in efficiency,thrust coefficient and the minimum of aerodynamic noise is treated as the optimization design objective.The spatial vorticity distribution of the propeller before and after the design is also analyzed by using unsteady computational fluid dynamics method.The results show that the optimized propeller can effectively reduce the aerodynamic noise level.The maximum total sound pressure level can be reduced by 5 dB without reducing its aerodynamic performance.The developed method has good application potential in low-noise optimization design of propeller and other rotating machinery.