合肥通用机械研究院有限公司

The stress intensity factor at the free surface is a core calculation parameter in the typical crack propagation and life prediction process of ultra-high-pressure vessels.Based on the segmented linear interpola-tion method,an improved method based on high-order polynomial fitting calculation was proposed.With blind bottom cracks as an example,stress data under different collected data volumes were fitted by means of poly-nomials of different orders;The stress intensity factors at the free surface of different cracks was calculated with this method,and the effects of polynomial orders and data amounts on the calculation results were ex-plored;At different crack depth to length ratios,the differences between this method and the recommended lin-ear interpolation method in previous literatures and the finite element method,were compared and analyzed.The results indicate that,as the polynomial order increases,the calculation results show a gradually approac-hing and converging trend.The minimum relative error of the calculation results for conventional cubic and high-order polynomial fitting is about-30%;As the collected data amount continues to increase,the calcula-tion results gradually converge towards a stable value.Comparison of calculation results between the cases with less and more data shows that,the maximum relative error can reach about 11%.This method,with its calcula-tion results,is basically consistent with the linear interpolation method in the previous literatures and the finite element method,and is suitable for dynamic crack propagation and life prediction processes.

In order to solve the problem of multi-source heterogeneous data fusion and improve the accuracy of reliability evaluation,a multi-source heterogeneous data fusion method based on approximate failure point was proposed by using D-S theory and the least squares method.Firstly,the probability envelope curves were obtained through constructing probability assignment for a single source of data and performing weighted fusion.A distribution fitting model based on approximate failure points was also established.Secondly,the parameter estimation value was obtained by the least squares method,and the area metric was constructed to determine the true failure distribution function,and then the reliability assessment was completed.Finally,the feasibility and effectiveness of the proposed method were verified by examples,and the accuracy was higher than that of Bayes method.

Quenching-partitioning (QP) steel combines ultrahigh strength with good ductility due to the martensitic transformation during plastic deformation. However, the formability of the QP1180 steel remains unclear. In this paper, the ultimate strains of the QP1180 steel under different strain paths are obtained through Nakajima experiment. The effects of the texture evolution and phase transformation on the forming limit of QP1180 steel are analyzed by using a crystal plastic finite element model coupled with the Marciniak-Kuczynski theory (CPFEM-PT-MK). The results show that the ultimate principal strain of QP1180 steel is the lowest under the strain path ζ=0.1, and the established CPFEM-PT-MK model successfully predicts the forming limit of the QP1180 steel sheet. The texture evolutions of the constituent phases in the QP1180 steel are different under various strain paths. According to the simulation, the texture evolutions enhance the forming limit of the QP1180 steel under various strain paths. Without phase transformation, the minimum limited major strain of the QP1180 steel is located at the strain path of ζ=0, which is significantly different from that when phase transformation occurs. Furthermore, the phase transition, related to the specific strain path, does not always enhance the forming limit of the QP1180 steel.

In energy public corridors， the similar routing of AC transmission lines and buried pipelines inevitably causes the pipeline to enter the AC interference zone， leading to pipeline AC corrosion， abnormal cathodic protection systems， and posing a threat to pipeline operation safety.To study the coupling interference law of AC transmission lines on buried pipelines， based on the pipeline equivalent circuit and electromagnetic induction theory， a model of AC interference of transmission lines on buried pipelines was established using CDEGS.The AC interference intensity and safety distance under typical transmission line characteristic parameters，pipeline parameters and laying environment parameters were calculated.Results showed that the AC interference voltage on the pipeline was directly proportional to the AC transmission current.When the parallel length between the 3PE pipeline and the transmission line was less than 20 km， the AC interference voltage was directly proportional to the parallel length.When the distance between the pipelines and transmission lines was small，the phase spacing and average height significantly impacted the AC interference voltage.As the distance increased， the AC interference voltage initially increased and then decreased.Based on extensive numerical simulations， a safety distance determination chart and AC interference voltage curve suitable for on-site engineering were proposed， providing a reference for selecting new pipeline routing and protecting existing pipelines from interference， thereby reducing the risk of AC interference on pipelines.

Data center computer room air-conditioning equipment operates for prolonged periods,and its performance must be tested and evaluated annually to ensure safe and efficient operation.This study conducts field measurements on the server layout,blind plate structure,and working condition adaptability in the rack.The thermal environment of a data center using the closed cold aisle underfloor air distribution system is studied,and the thermal environment safety and energy efficiency throughout the year are evaluated through thermal performance indicators and energy efficiency indicators.The results show that it is recommended to install a rack with a power of more than 2 kW in the middle area of the cold aisle.Installing a blind plate in the gap between the racks can promote the circulation of cold air inside the server,reduce the backflow interference of hot air,and reduce the maximum outlet temperature by 3.32℃.The average supply air speed was reduced by approximately 24%.Under summer operating conditions,the PUE,WUE,and CUE of the data center were approximately 1.2,3.5,and 0.84,respectively,and the WUE exhibited strong seasonality.Under winter operating conditions,free cooling can effectively reduce the energy consumption of data centers.In addition,the overheating problem of the racks at the end of the cold aisle of the data center is significant.The cabinet cooling index of the 16 racks was less than 90%,and the heat loss was high.