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Freight transport with heavy trucks has emerged as a significant energy-intensive sector and a major contributor to carbon emissions in China's transportation industry. The diesel consumption in this field represents approximately 40 % of China's total annual diesel consumption, while the CO2 emissions account for approximately 50 % of the total annual CO2 emissions in the transportation industry. Under the background of carbon peaking and carbon neutrality goals and energy revolution, it has become an inevitable trend to build a green, secure and efficient road freight mode and promote the low-carbon and clean transformation of heavy freight transport. So far, the electrification options of freight transport with heavy trucks mainly include charging, battery swapping, hydrogen heavy trucks, and electrified highways. This paper mainly introduces the hydrogen heavy truck and electrified highway options. Based on a dedicated coal transport route, the economic efficiency and application scenarios were compared and analyzed between these two options from a perspective of cost estimates. The analysis results show that, for this dedicated coal transport route, when the annual traffic volume is greater than 2.0483 million tons, the electrified highway option is more economical, while on the contrary, the cost of the hydrogen heavy truck option is lower.

one support frame was designed for the independent suspension of 8 × 8 off road chassis,on purpose of that connect two suspension brackets. The frame was damaged after vehicle enhance road test with the weld seam cracked and the bolt cut off. According to the failure performance,the model about independent suspension included support frame was built for failure analysis,and the failure was caused by uncoordinated deformation of different parts; the support frame is improved and verified by simulation and test.

The high power transfer case as a key component of a multi-axis super-heavy chassis transmission system,with the characteristics of large torque,high speed,and large temperature difference,rely on splash lubrication and natural air cooling has been unable to meet the need of the chassis for high mobility,high through off-road and extreme ambient temperature. It is necessary to use the forced lubrication system to lubricate the internal hot spots of the transfer case,especially the bearing position. Therefore,the power thermal energy model of the hotspots of the transmission parts is built first,through the heat balance conditions,the flow demand of the lubrication point and the overall are estimated,and then a hydraulic simulation analysis model is established,the matching lubrication system piping is designed. Aiming at the problem of the natural air cooling can’t achieve the system thermal balance requirements in the great power of the transmission system,by calculating the surface wind speed and heat dissipation surface,the heat dissipation capacity of the transfer case itself is evaluated,the external air-cooled radiator and fan are matched according to the heat dissipation requirement.Finally,through the bench and running vehicle test,the design of the high power transfer case forced lubrication system to meet a multi-axis super-heavy chassis of the use of the requirements is verified.

Aiming at the structure of transmission case housing used in electric vehicle,the topology optimization analysis of transmission case housing used in electric vehicle,including the external and internal reinforcing plates and outside profile is conducted by using the method of topology optimization analysis from the forward design. In the optimization,the minimum weighted compliance is set as the optimization objective and volume fraction,displacement,stress,modal frequency and machining technology as constrains. Based on the topology optimization result,the optimization design of transmission case housing is carried out with considering the requirements of assembly,lubrication and cooling. Furthermore,the stresses state and modal frequency of the transmission case housing is also calculated in order to verify its structural strength and vibration performance. The analysis results show that the structural strength and modal frequency of the optimized transmission are higher than the design index,the optimization design of the complicated transmission case housing structure is realized.

In the multi-axis super-heavy-duty test platform,the high-power transfer case has the problem of broken teeth during fatigue endurance. The comprehensive analysis is carried out on the failure gears,the causes of gear damage,such as gear strength,shaft and box stiffness,gear tooth profile and tooth orientation precision,surface heat treatment,etc. are analyzed one by one,and finally it is positioned as the gear tooth surface grinding burns,resulting in reduced hardness of the tooth surface,contact fatigue strength decreased,the occurrence of premature failure damage. In the improvement work,the grinding process of the gear tooth surface is modified,and 100% grinding burn monitoring is added. The improved high-power transfer case passed the fatigue endurance test.

The wheel gearbox is a key component of Multi-axis super-heavy hybrid test platform,for the special nature of the application,on the one hand to meet the requirements of vehicle wheel power transmission requirements,while also meet lightweight and high reliability requirements.Therefore,in the wheel gearbox design,taking the lightweight for the wheel gearbox as the target,reliability as constraints,the optimization design scheme of the wheel gearbox is proposed.After the high- speed test,full load fatigue test and overload fatigue test verification,the wheel gearbox performance and reliability meet the requirements of super- heavy hybrid multi- axis test platform.

The topology optimization design of the complicated transfer case housing is conducted by using the variable density method. Taking the minimum compliance as the optimization objective and the volume fraction,static displacement,static stress,modal frequency and machining process as constrains condition,the topology optimization analysis of external shape and internal rib plate are carried out. Then,the static strength and modal character analysis of the optimized transfer case housing are carried out. The analysis results demonstrate that the static strength and modal frequency are higher than the design objective,the topology optimization design of complex housing structure is realized.

In order to study the permeability evolution law of coal and rock under the action of mining dynamic load, the Darcy law steady-state measurement method was adopted to conduct the stress-strain permeability experiment of coal and rock using the triaxial compression permeability experiment device. The experimental results show that the increase of confining pressure prevents the development of tensile crack, resulting in the increase of stress peak and permeability decrease of the total stress-strain curve of coal and rock. With the same confining pressure, the variation trend of the coal rock strain-permeability curve and the stress-strain curve is basically the same, and there is a causal relationship, resulting in the hysteresis of the coal rock strain-permeability curve compared with the stress-strain curve.