Dengpan Zhang, Xianjin Liu, Yibo Zheng, Xian Zhao

As a commonly used transmission device, cylindrical gear system is widely used in the fields of mechanical manufacturing and industrial production. However, due to the problems of low transmission efficiency, high noise, and severe wear in the gear system, optimization design is needed to improve its performance. This article combines modern computer-aided design technology to establish a three-dimensional model of the gear system, and introduces various parameters under excitation, including manufacturing errors, elastic deformation of shafts and bearings, to design the cylindrical gear transmission system. The performance of the modified gear transmission system has been significantly improved under different excitation effects, with a reduction of 44% in peak transmission error and 52.5% in peak transmission acceleration, respectively. At the same time, the normal force distribution on the modified tooth surface is relatively uniform, and the service life of the system has been extended. This study indicates that introducing multiple excitation effects for shape modification design in the optimization design of cylindrical gear systems can effectively improve their performance. The research results have important practical significance for improving the transmission efficiency and stability of gear systems and guiding the design and manufacturing of gear transmission systems.

Dengpan Zhang, Yibo Zheng, Xianjin Liu, Xian Zhao

The design and manufacture of gears have gradually been digitized, intellectualized and networked. The quality evaluation based on gear measurement is the key to ensure the quality of gears manufacturing. In order to digitize and informationalize the gear quality evaluation process and solve the problem of "information island" in gear measurement, this paper puts forward a gear quality evaluation scheme based on cloud service. First, the framework of gear quality evaluation cloud service is introduced, and the method of publishing and invoking the gear cloud service function based on REST is proposed. Then this article studies the gear accuracy evaluation method and statistical analysis method based on cloud service, and analyzes the gear quality evaluation cloud service process. Finally, a gear quality cloud evaluation system is developed, and the function and software of the cloud platform are tested through actual measurement. The test results show that, compared with the traditional scheme, the cloud service scheme of gear quality evaluation can realize the integrated sharing of gear measurement data and digitization and information of gear quality evaluation process. The service of evaluation results can improve the efficiency of gear quality evaluation.

J. Alrajhi, K. Alhaifi, M. Alardhi, N. Alhaifi, J. Alazmi, A. Khalfan, K. Alkhulaifi

A numerical analysis of a Single Degree of Freedom Vibration (SDOF) vibration system with non-linearity is investigated. Mag-spring as a nonlinear spring with hardening behaviour is added in parallel to a vibrating system. The nonlinear effect is expected to curve the vibration amplitude and shift away the system’s natural frequency only where it is necessary. Due to hardening behaviour of the nonlinear Mag-spring especially at higher amplitudes, nonlinearity kicks in and the stiffness of the system is increased; then the natural frequency of the system is shifted to a higher value away from the excitation frequency. It has been shown that how a light damping could lead a forced vibration system to a steady state. Moreover, it explains how a nonlinear spring can be fitted in parallel to the main system with one degree without changing its degree of freedom. The techniques utilised to formulate the equation of non-linear spring have been explained as well. Based on the characteristics of the nonlinear spring, a system with appropriate parameters has been formulated. Further, a second order nonlinear differential equation is solved by a written program in MATLAB software. It shows how the initial conditions and the differential equation in a state space form will be used by ode45 function in MATLAB to solve the system.

Jasem Alrajhi, Khalid Alkhulaifi, Mohsen Alardhi, Khaled Alhaifi, Nawaf Alhaifi, Ahmed Khalfan, Jasem Alazemi, Marya Alsaraf, Ahmad Khalfan

By examining friction pairs surface structural features and using theory of contact mechanics, contact mathematic prototype of microscopic units of thermal distortion friction pairs is made. Using mathematical statistics and normalization method, microscopic model can be removed to macroscopic mathematic model, and then the elastic contact features of friction pairs can be premeditated. A nonlinear dynamic model with five degrees-of-freedom for a four-wheel-drive vehicle driveline coupled by a cardan joint, counting dynamic connection angle, nonconstant velocity, and supplementary instant caused by the cardan joint, is recognized by using the Lagrange method to analyse the driveline coupling vibration in both torsional and lateral directions. High-order Runge–Kutta algorithm is practical to solve the differential equations and to calculate momentary replies of the driveline rotors under acceleration state. The colour maps and second-order vibration of the driveline are attained by frequency spectrum analysis and order tracking analysis, respectively. The second-order vibration and noise of the driveline and vehicle interior caused by the cardan joint is authenticated by vehicle tentative results and condensed efficiently by reducing intersection angle of the cardan joint under the functioning condition. Results shows that application of an elastic coupling as an alternative of the cardan joint knowingly diminishes the second-order vibration but instantaneously creates low-level third-order vibration.

Alardhi M., Alrajhi J., Alkhulaifi K.

Experimental results of in-cylinder and fuel injection characteristics measurements in direct injection diesel engine using automotive diesel (AD) and water diesel emulsion (WDE) have been investigated at two engine speeds and loads. Experimental results have shown that the magnitude of cylinder pressure of WDE during most of the cycle and peak pressures are close to those observed for AD at both speeds and loads. The late SOC for WDE causes the fuel energy to be released during most of the expansion stroke resulting in a higher cylinder pressure. Differences in WDE fuel properties such as bulk modulus, density and viscosity cause the start of fuel injection pressure rise to occur much earlier than that of AD. Although the higher bulk modulus of WDE should result in an earlier SOI, however, the opposite has been noticed here. In terms of exhaust emissions, the lower combustion temperature of WDE is expected to cause a lower NOx emission.

Xiaozhuan Chen, Pan Wang, Xuefeng Meng, Beile Zhang, Xiufang Liu

To meet the environmental requirements, the air-conditioning system of an electric vehicle is chosen as the research object. In this study, under the same operating conditions, the differences in cycle characteristics of R134a, R513A, and R152a refrigerants have been investigated theoretically and experimentally. The REFPROP 9.1 software is used to extract the thermodynamic properties of the refrigerants, and the thermodynamic performance is simulated in a basic vapor compression system cycle. To study the effects of ambient temperature as well as compressor speed on performance characteristics, an electric vehicle air conditioning system with a secondary loop was designed and built. The results that the cooling capacity and outlet air temperature of R513A and R152a systems are similar to that of R134a, but the coefficient of performance (COP) of the R152a system is 13% and 15% higher than that of R134a and R513A, respectively. The ambient temperature and compressor speed have a clear impact on cooling performance. The COP declines dramatically at high ambient temperature and compressor speed. R152a can be considered a promising alternative to R134a system for its low cost, and high efficiency, which enhances the driving range.

Xiaozhuan Chen, Pan Wang, Yongfu Li, Chenzhao Wu, Xiaoru Hao

Scale is a problem that has not been solved thoroughly in industry and academia. An experimental system was built in order to study the effects of heat flux, bulk fluid temperature T_b, and solution hardness & flow velocity on scale formation. Preliminary experiments were conducted to test the reliability and stability of the experimental apparatus. The experiments revealed growth law of thermal resistances under four action factors. The experimental results showed that the bulk fluid temperature T_b had important influence on the formation process of scale. When T_b increases from 24°C to 28°C, the fouling resistances increase from 1.46×10^-4 m²·K/W to 3.01×10^-4 m²·K/W. The fouling resistances decrease with the increase of flow velocity. Four important factors were ranked from greatest to least in the following order: heat flux, T_b, solution hardness and flow velocity under the guidance of grey relational analysis method. Calcium carbonate crystal particles precipitate out from the metastable solution. The type of fouling deposited on inside surface of copper pipe from microparticles in solution can be defined as particulate fouling. Therefore, the fouling deposited on the inside surface of the copper pipe should be named composite fouling included crystallization fouling and particulate fouling, based on the whole process of scale precipitated from solution. These research results can provide theoretical basis for the prevention and removal of scale on the surface of heat exchanger.

Dengpan Zhang, Jian Li, Jiajia Yue, Frank Härtig, Hongliang Zhang, Yibo Zheng

Gear is the key basic component of industrial equipment. Gear measurement has shown the characteristics of networking and cloud. In order to adapt to the rapid development of gear tooth surface measurement technology, this paper establishes a gear accuracy evaluation online service system based on cloud platform. The service provides different fitting algorithms for three-dimensional tooth surface deviation, realizes the three-dimensional visual expression of tooth surface deviation, and allows users to evaluate the whole tooth surface deviation of gear on line; In addition, the system realizes the standardization of gear measurement cloud data based on GXML data model, which is convenient for the storage and transmission of measurement results between different devices. Finally, the system saves the user's evaluation results in GXML data model and generates the corresponding detection report, which provides data support for the subsequent analysis of tooth surface deviation, improvement of gear manufacturing process and error traceability.

Charles A. Odada, Jean B. Byiringiro, Fredrick M. Madaraka

Fused deposition modelling (FDM) and digital twinning are considered important areas to the future of manufacturing. However, both technologies still face major challenges to their adoption. Errors in printed products are still common in FDM, while cost and gaps in knowledge and technology have made digital twins inaccessible for many. This paper presents the design and use of a data-driven digital twin of an FDM 3D (three dimensional) printer that was used to monitor the motions of a 3D printer in real-time. Sensors attached to the physical 3D printer were used to gather motion data for the virtual 3D printer modelled in Siemens NX. Communication to the virtual printer was handled by a Modbus server and an OPC-DA (Open Platform Communications—Data Access) server. Tests were performed to evaluate the virtual 3D printer’s ability to monitor the real 3D printer’s movements in real-time, the relationship between the printer’s motions and the generated vibration signals, and the digital twin’s ability to repeat the motions from past printing sessions using logged data (history tracking). The results showed that a virtual 3D printer can be used to monitor the motions of an FDM 3D printer in real-time with a maximum average time lag of 0.351 seconds. The vibration patterns generally reflected the state of the physical system. Lastly, the history tracking feature was able to repeat the motions from previous printing sessions using the logged data but introduced some extra lag.

Didit Sumardiyanto, Sri Endah Susilowati

This research was conducted on the HANSHIN type LH36L engine which is the main engine of MV. Poertocurtis. This research was triggered by the emergence of disturbances in the form of vibrations on the machine. In connection with these conditions, it is necessary to conduct research to determine the source of the problem so that the same condition does not recur in the future. The method used in this research is to dismantle the generation of elements and measure the mass of each element needed for calculations. The data obtained in the field, assuming a maximum load of 130% of the engine output power, shows that the maximum effective power, N_e is 2 486 kW, indicated power N_i is 2 825 kW, and indicated pressure, P_i is 307 N/cm². The thrust of the piston, F_gh is 552 640 N, the reciprocating inertia force, F_j is 62 316 N, the total force received by the piston pin, F_sum, and the force received by the crank pin, F_cr is 616 780 N, the average plane pressure journal k_max is 162.5 kg/cm², and the working bearing characteristics, λ_cr is 58.15, which is still below the tolerance limit. So that the wear of the crank pin bearing that occurs on the main engine MV. Poertocurtis is caused by impurities in the form of combustion carbon that enter the lubricating crankcase.