Study on bearing mechanical and thermal characteristic evolvement rules affected by higher ambient temperature

In this paper, the bearing mechanical characteristics and thermal characteristics as it is running under constant speed (2400 r/min) and constant temperature (100 ℃) adopting bearing mechanical-thermal coupling model built on the basis of quasi-statics and elastohydrodynamic lubrication theory are discussed. Among which, the contact deformation between ball and inner/outer ring has same evolution law, besides, the same as the amplitude. Whose curve shape changes in the form of “circular-oblique D”, its amplitude rearches minimum value at 10thd3h between the location of 120° and 270°. The curve shapes belonging to contact angular between ball and inner/outer ring are similar to “circular”. There is opposite trend of them within the range of 90-300°. The amplitude of contact angular between ball and outer ring is the minimum at 10thd3h and 11thd1h. At the same time, the amplitude of that between ball and inner ring is the maximum. The evolution rules of contact stiffness between ball and inner/outer ring are generally consistent, which are similar to “crab”. But the amplitude of that between ball and outer ring is dominant. The maximum value of them occurs at 10thd3 and 11thd1h. The evolvement tendency of node temperatures maintains stable. Thereinto, the temperature of inner ring equals to that of contact location between ball and inner ring, which is the maximum value. It is obvious that ME, MD, MS, MCB, MCR and MOil devote themselves to heat production, the contribution rates of ME, MS, MCB and MCR are 100 %, the contribution rate of MD ranges from 52.6 % to 65.2 %. However, the amplitudes of friction moments have the opposite trend compared to “heat contribution factor”. The expansion amount owing to heat production is dominant in displacement variation and the effect of clearance on displacement can be ignored, whose evolution rules are contrary. The evolution rules of oil film thickness and oil film stiffness between ball and inner/outer ring are alike. Among which, the oil film thickness between ball and outer ring is dominant, its maximum value emerges at 10thd3h. The curve shapes of oil film stiffness between ball and outer/inner ring are oblique “D”, their amplitudes reach the maximum at 11thd1h-11thd3h

Analysis of electromagnetic characteristic in the interior permanent magnet brushless DC motor

The motor vibration is mainly induced by the electromagnetic excitation. In order to improve the running performance of the permanent magnet brushless DC motor (BLDCM) within the rolling rotor compressor, this paper builds the predicted model of the electromagnetic excitation and analyzes the electromagnetic characteristic of the BLDCM. Firstly, the electromagnetic field is divided into four regions in 2D plane, including the magnet, air gap, stator slot, and slot-opening subdomains. Then, the relative equations of the electromagnetic field are constructed, and the vector magnetic potential is solved by the variable separation method. Thus, the magnetic flux density of the air gap is derived by the corresponding vector magnetic potential, which is used to describe the electromagnetic excitation. Based on the built model, the effects of the slot opening and air gap length on the electromagnetic characteristic are analyzed. The analysis results can provide a reference for the improvement of the electromagnetic characteristic of the BLDCM by structure optimization

Socio-political development of CC(U)S in the Baltic Sea region

According to EU goals and the Paris Agreement, an urgent need exists to reduce CO2 emissions while still securing energy supply. Thus, the timely deployment of carbon capture and storage (CCS) is seemingly unavoidable, especially for the cement and steel industries. However, diverse perceptions of CCS among stakeholders such as experts, politicians, and laypeople exist that could hinder the deployment of the technology, not least in the Baltic Sea Region (BSR). Hence, this research discusses these diverse perceptions and their roots. Furthermore, when it comes to political developments of CCS, after the unprovoked Russian invasion of Ukraine, the whole process of the energy transition in the region is under shadow for the seemingly mid-term while the approach to the energy security and security of supply needs to be revisited. In other words, the countries of the BSR need to manage the energy crisis in the region while following their plans for decarbonisation. In this light, CCS is, therefore, an option to secure energy supply from undesired alternatives like fossil fuels for the short-term and also biomass while curbing CO2 emissions. In sum, this research also discusses the role of CCS in energy security and security of supply concerning the Russian invasion of Ukraine

Experimental study on creep wetting of silty clay

To study the wetting of a silty clay subgrade in an expressway, many laboratory tests were carried out. The test results show that the creep deformation of silty clay under water immersion cannot be ignored, but it is different from the deformation caused by wetting. The creep properties of soil mass are affected by many factors. Under different stress conditions, the soil mass will show different properties. In order to study the creep characteristics of silty clay in Chongqing under water wetting and different stress levels, a series of triaxial water wetting creep tests were carried out. The Singh-Mitchell creep equation was introduced to establish the creep model of silty clay drainage in Chongqing, and the parameters of the model were discussed

Research on dynamic stability of large deformation roadway with application of segmented resistance anchor bolt

The dynamic stability of large deformation roadway can be significantly affected by seismic vibration. In order to improve the support effect, a segmented constant resistance anchor bolt structure is proposed. The preload can be set in segments to effectively reduce the tension deviation. The support stability of this type of bolt is verified by field test and experimental simulation. Based on the bearing and deformation characteristics of surrounding rock, the supporting and installation, grouting process and anchor cable stress monitoring of this type anchor bolt are designed. Through the field measurement of the roadway, the variation laws of the rock swelling coefficient, anchor cable tension and roof subsidence under the condition of bolt support are obtained. A tunnel dynamic deformation test-bed is built to study the dynamic vibration response of the designed anchor bolt to alternating load. Applying orthogonal exciting force, the tension changes in different constant resistance sections are obtained. The results show that this type of bolt has remarkable effect of resisting alternating load, and the maximum tension deviation within ±200 m working face is less than 8 %, which has better support stability than conventional bolt

Experimental investigation of damping characteristics of sandwiched engine isolators using two-way isolator excitation method (TWIEM) and performance evaluation

Dynamic properties of engine isolators are of significant importance in determining the performance of the isolator and precise prediction of the dynamic behavior at the design stage. Unfortunately, the damping property can not be deduced deterministically from other structural properties because it is highly dependent on dynamic shear properties such as frequency and temperature of material under application. Generally damping properties are determined from experiments conducted on the desired setup. Many times, designers use the damping property data available in literature. Such data may not be recommended for development of predictive models for dynamic behavior. This paper presents a novel method of determination of damping property of the engine isolator. The method is called two-way isolator excitation method (TWIEM). The damping property is determined by excitation of the isolator for active and passive transmissibility. The purpose of this paper is to analyze the vibration isolation by checking the transmissibility ratio for various engine isolators. Sandwiched engine isolators are designed to blend the good properties of different isolation materials to make it more efficient. The experimentation was carried out using three different isolator designs and compared the performance of the isolator on the basis of isolation percentage. Mild steel plates, polymer foam sheets and natural rubber materials are used as Isolator materials. The results show that low damping ratio isolating material is more effective in isolating the vibration source