Experimental research and application of cold cutting to hot stamping parts based on multiphase microstructure

Among the bottlenecks that hinder the improvement of the production efficiency of hot stamping are high strength and difficulty in edge cutting and hole punching.Starting from the preparation of hot stamping multiphase microstructure materials,this paper developed a plate quenching die system with controllable surface temperature and prepared four types of hot stamping plates with different martensite volume fractions.Then,straight edge cold cutting experiments were performed to study the influence of cutting clearance and cutting force on fracture quality.The results show that the bright zone is the largest when the cutting clearance is 0.14 mm,and the cutting experience coefficient of the hot stamping sheet with each martensite volume fraction is obtained when the cutting clearance is 0.14 mm.The research results of this paper were applied to the production of hot stamping parts.

Analysis and optimization of stamping and forming process of bearing outer ring

To address the common issues of wrinkling,tearing,and uneven wall thickness in the actual sheet metal stamp-ing process of the outer ring of needle roller bearings,this study analyzes critical technical indicators such asforming limits,thickness distribution,and principal strains in the forming process in detail.Three-dimensionalmodels of the concave and convex dies were constructed.The effects of different process parameters,includingstamping speed,edge pressure,sheet metal thickness,and friction coefficient,on the quality of the forming partswere investigated by varying these parameters.Subsequently,the orthogonal experimental method was used todetermine an optimal experimental group from multiple sets of experiments.It was found that under the processparameters of a stamping speed of 3000 mm/s,edge pressure of 2000 N,sheet metal thickness of 0.9 mm,andfriction coefficient of 0.125,the forming quality of the outer ring of the bearing is ideal.

Microstructure and performance evaluations on Q&P hot stamping parts of several UHSS sheet metals

Hot stamping(press hardening) is widely used to fabricate safety components such as door beams and B pillars with increased strength via quenching. However, parts that are hot-stamped from ultra-high-strength steel(UHSS) have very limited elongation,i.e., low ductility. In the present study, a novel variant of hot stamping technology called quenching-and-partitioning(Q&P) hot stamping was developed. This approach was tested on several UHSS sheet metals, and it was confirmed that this method can be used to overcome the drawbacks associated with conventional hot stamping. The applicability of Q&P hot stamping to each of these steels was also assessed. The part properties and performances of three widely used ultra-high-strength sheet metals, B1500 HS,27 SiMn, and TRIP780, were evaluated through tensile testing and microstructural observations. The results demonstrated that the ductility of Q&P hot-stamped sheet metals was notably higher than that of the conventionally hot-stamped parts because Q&P hot stamping gives rise to a dual-phase structure of both martensite and austenite. Further, material tests demonstrated that the Q&P treatment had positive effects on all three selected materials, of which TRIP780 had the best ductility and the highest value of the product of strength and plasticity. Scanning electron microscopy images indicated that the silicon in the steels could limit the formation of cementite and would, therefore, improve the mechanical properties of Q&P hot-stamped products.

Effect of Contact Pressure during Quenching on Microstructures and Mechanical Properties of Hot-stamping Parts

An experimental apparatus with cooling system and pressure-adjustment assembly for simulating quench- ing was constructed to investigate the effect of contact pressure on the microstructures and mechanical properties of hot stamping parts. Qualitative and quantitative analyses of the microstructures of the as quenched parts were con- ducted; moreover, hardness and tensile tests were performed to measure their mechanical properties. The results in- dicated that contact pressure during quenching strongly affected the structures and performances of hot-stamping components. An excessive low contact pressure led to insufficient martensitic transformation. The critical contact pressure for complete martensitic transformation for 4.0 mm 22MnB5 steel was 0.4 MPa when the temperature of the coolant was 20 ℃. However, in consideration of the efficiency of practical production, a contact pressure higher than 1.25 MPa is recommended.

Analysis of roll-stamping process for rib grooves of ultra-high-strength beam parts

Roll-stamping technology,a new process with both roll-forming and stamping characteristics,is suitable for manufacturing ultra-high-strength beam parts,especially variable cross-section beam parts.The rib groove is a local shape often used in automotive parts for positioning,avoidance,and stiffness strengthening on longitudinal and stiffening beams.In this study,two typical rib grooves,the flat-and round-bottom rib grooves,were selected to investigate the characteristics of the roll-stamping process of rib grooves.Using the ABAQUS software platform,a simulation analysis model of rib-groove roll stamping was established and different size rib grooves produced by the roll-stamping process were compared and analyzed.The results show that when the fillet radius of the rib groove increases,the maximum Mises stress,the maximum strain,and the maximum thinning rate decrease.For roll stamping,the minimum safe fillet radii of the two types of rib grooves are 8 and 4 mm,respectively.

Residual Stresses and Forming Quality of Metal Bipolar Plates for PEMFC During the Stamping Process

Stamping is a critical step in the manufacture of metallic bipolar plates.Typically,residual stress and a spring back effect appear on the bipolar plate after the stamping process,which impacts on the performance and lifetime of the proton exchange membrane fuel cell(PEMFC).The residual stress and spring back behavior which occur as a result of stamping a bipolar plate are investigated in this study.The effects of the punch radius,the die radius,the channel depth,and the clearance between the punch and the die on the residual stress and forming quality of the bipolar plate are examined.The stamping process can be divided into three stages.The high stress area and the middle section residual stress area were selected to study the formation process and to obtain the composition of the residual stress regions.Spring back was mainly related to the position of the fixed end of the sheet and the degree of plastic deformation,and the sheet thickness have increased by 2μm after spring back.Based on the results of finite element analysis,as described by the distribution of residual stress,the formation,the thickness of the middle cross section and the equivalent plastic strain,it was found that all the tool parameters affected the distribution of the residual stress.This research can provide a design reference for the manufacture of metallic bipolar plates based on the stamping process.

Application of new generation low-strength hot stamping steel to improve the crash performance of BIW

With the improvement of safety performance,car parts have different requirements for material strength and energy absorption performance.The conventional 1500-MPa hot stamping steel cannot well meet the requirements.Considering the new generation 600-MPa hot stamping steel,this study investigates the applicable car parts and hot stamping process,then designs a new body-in-white(BIW)crash test for obtaining the crash performance of the new material.Through the actual part development and crash test,it is verified that the application of the new generation hot stamping steel can improve the crash performance of BIW.

多重防护机制下LNG动力船风险态势分析方法

为探讨多重防护机制下的液化天然气(Liquefied Natural Gas,LNG)动力船营运风险特征,提出了一种基于复杂性控制系统作用模式的风险态势分析方法。从系统控制过程视角,采用系统控制过程分析方法(System-Theoretic Process Analysis,STPA)确立LNG动力船系统安全控制的风险致因,揭示基于LNG泄漏三重防护机制的风险因子体系和风险形成机制;引入隐马尔可夫模型(Hidden Markov Model,HMM),进行无监督学习并确立模型参数,推理多重防护机制下的LNG动力船风险转移特征;结合LNG动力船营运的具体场景,对三重防护机制分别进行仿真并统计风险态势。仿真结果表明,三重防护机制在降低LNG动力船营运风险态势方面具有因子诱导的针对性,在防漏因子、止漏因子和治漏因子诱导下LNG动力船分别趋向一般风险状态、较高风险状态和高风险状态。基于复杂性控制系统作用模式的风险态势分析可为LNG动力船营运的安全控制和风险管理提供管控模式和手段。

郑州“7·20”地铁水淹事件STAMP致因分析

为探讨河南郑州“7·20”地铁5号线伤亡事件致因,综合运用系统理论事件模型与过程(STAMP)模型,分析5号线伤亡事件安全控制结构,据此逐级辨识事件致因;基于复杂网络理论将事件致因及其联系抽象为网络的节点和边,建立地铁水灾事件网络;计算聚类系数、度数等拓扑参数定量分析事件致因性质,确定关键致因。结果表明:地方党委政府面对汛情的应对部署不紧不实,缺少有效的组织动员和有关部门对工程建设存在失管失察是事件的深层根源;建设单位、设计单位等五方主体单位及运维单位的主体责任失职是事件的主观关键致因;应从政府及有关部门、五方主体单位和运维单位方面采取多元协同的风险防控措施。

基于系统论事故分析模型的油气智慧管道系统信息物理风险辨识

为了辨识油气智慧管道系统中存在的信息安全风险,通过基于系统论事故分析模型(systems-theoretic accident modeling and process,STAMP)的方法,对油气智慧管道系统的信息物理安全进行全面评估与分析。首先,系统综合分析了油气智慧管道涉及的设备、设施、工艺、元件,评估其安全性。其次,通过建立STAMP模型,深入分析了各层级、元件之间的反馈信息与控制动作,形成了明确的控制反馈回路,突显了元件之间的关联与控制关系。在此基础上,系统辨识出了潜在的信息风险因素,推导并构建了可能发生的系统失效场景。以天然气输气首站油气智慧管道系统为例,研究验证了基于STAMP模型的可行性和有效性。结果显示,该方法不仅直观地描述了元件之间的关联与控制关系,而且从物理层功能安全的角度全面考虑了信息风险,特别凸显了过程控制系统(process control systems,PCS)及易受攻击的操作员站。与传统方法相比,本研究所提出的方法将信息物理安全风险因素的识别率提升至80%以上,提高了40%以上,有助于避免不必要的安全措施冗余设计,提高了安全风险管控的准确性。

采用STAMP-24Model的多组织事故分析

安全生产事故往往由多组织交互、多因素耦合造成,事故原因涉及多个组织。为预防和遏制多组织生产安全事故的发生,基于系统理论事故建模与过程模型(Systems-Theory Accident Modeling and Process,STAMP)、24Model,构建一种用于多组织事故分析的方法,并以青岛石油爆炸事故为例进行事故原因分析。结果显示:STAMP-24Model可以分组织,分层次且有效、全面、详细地分析涉及多个组织的事故原因,探究多组织之间的交互关系;对事故进行动态演化分析,可得到各组织不安全动作耦合关系与形成的事故失效链及管控失效路径,进而为预防多组织事故提供思路和参考。

基于STAMP-偏序集的非煤矿山爆炸事故系统风险评估模型

通过提出一种基于STAMP偏序集的系统性风险评估模型,揭示非煤矿山爆炸事故的发生机理,并为爆炸事故的有效预防和控制提供参考。首先,利用STAMP模型构建了非煤矿山爆炸事故的系统层次结构,确定了事件集及其层次关系,并从系统设计和安全控制的角度分析了事故的致因因素;然后,采用排序质心法计算了事件集的初始概率,并将概率矩阵作为偏序集评价模型的输入,得到了因素间的聚类关系和节点脆弱性;最后,通过一个实例验证了该模型的有效性和可行性。该模型能够图形化地描述各致因因素间的聚类关系、节点重要度以及系统各组件间的关系,从而能够有效识别系统的脆弱性节点,并为爆炸事故预防提供科学合理的控制措施。

基于时序InSAR的辽河油田地表形变监测及储层参数多模型反演

为获取辽河油田核心产区最新的地表形变与储层参数,基于2021-01~2023-06的Sentinel-1升轨影像,使用StaMPS-SBAS方法提取该区域地表形变。以形变速率结果为观测量,使用复合位错模型、Mogi模型和Okada模型对储层参数进行反演,并与已有研究进行对比分析。结果表明,研究区LOS向形变速率为-165.84~54.52 mm/a,研究时段内最大累积沉降量(LOS向)约为400 mm。区内存在3个显著沉降区,分别为曙光采油厂、欢喜岭采油厂和锦州采油厂,其中曙光采油厂存在一定的沉降减缓趋势,其余采油厂均存在沉降加速趋势。不同模型反演的储层参数存在明显差异,与Okada模型、Mogi模型相比,复合位错模型反演的储层深度(1 665.21 m)与实际最为接近(约1 600 m),且复合位错模型模拟的形变与观测形变最为吻合。

Forming defects in aluminum alloy hot stamping of side-door impact beam

The forming defects, including thinning, rupture, wrinkling and springback, usually arising in producing a side-door impact beam, were investigated by trial and numerical simulation. A temperature-related constitutive model specific to the temperature range from 350 °C to 500 °C was established and used for the numerical simulation. The trial and numerical simulation were conducted to clarify the quantitative characteristics of forming defects and to analyze the effects of process parameters on the forming defects. Results show that the rupture situation is ameliorated and the springback is eliminated in the aluminum alloy hot stamping. The wrinkling severity decreases with increasing blank holder force (BHF), but the BHF greater than 15 kN causes the rupture at the deepest drawing position of workpiece. The forming defects are avoided with lubricant in the feasible ranges of process parameters: the BHF of 3 to 5 kN and the stamping speed of 50 to 200 mm/s.

Formability of aluminum-silicon coated boron steel in hot stamping process

Flow behavior of the Al-Si coated boron steel was investigated with Gleeble-3500,in comparison with the uncoated one.Effect of deformation conditions on the coating integrity was characterized by optical microscopy.Facture surfaces of the coated steels were inspected under SEM.Experimental results indicate that the ultimate tensile strength and ductility of the Al-Si coated boron steel are lower than those of the uncoated steel under test conditions.Extensive cracks occur in the coating after tensile tests;the width and density of cracks are sensitive to the deformation temperatures and strain rates.The bare substrate exposed between the separate coating segments is oxidized.Appearance of the oxide degrades the Al-Si coating adhesion.Remarkable difference between formability of the coating layer and the substrate is confirmed.The formability of the Al-Si coating could be optimized by controlling the phase transformation of the ductile Fe-rich intermetallic compounds within it during the austenization.

基于STAMP与模型检验的全自动无人驾驶复杂运营场景安全验证方法

与传统列控系统相比,全自动无人驾驶运营场景更加复杂多变,潜在的危险及致因具有更强的隐蔽性和复杂性,给运营安全带来了新的挑战。针对以上问题,提出一种STAMP(Systems-Theoretic Accident Model and Process)与模型检验相结合的复杂运营场景安全验证方法。首先,基于STAMP理论构建运营场景分层控制结构模型,辨识潜在的不安全控制行为、分析危险致因和安全约束;其次,定义分层控制结构模型与安全状态机模型间的基本转换规则,基于分层控制结构模型、安全约束和转换规则,构建运营场景安全状态机模型;最后,针对提取的安全约束,利用数据流图建立安全属性验证模型,结合模型检验技术,对运营场景安全状态机模型进行形式化验证。以全自动无人驾驶运营场景中列车自动进站停车为例,对方法进行验证分析。结果表明,当STAMP理论提取的安全约束通过了场景安全状态机模型的验证时,表示在该场景中对应的不安全控制行为没有发生且不导致相应危险。该方法结合系统安全分析与形式化建模验证的优势,降低了运营场景建模的难度,构建的运营场景形式化模型满足系统安全约束,可以作为全自动无人驾驶系统安全设计和安全改进的重要基础。

Experimental and simulation research on thermal stamping of carbon fiber composite sheet

To improve the manufacture efficiency and promote the application of composites in the automobile industry, a new composite forming method, thermal stamping, was discussed to form composite parts directly. Experiments on two typical stamping processes, thermal bending and thermal deep drawing, were conducted to investigate the forming behavior of composite sheets and analyze the influence of forming temperature on the formed composite part. Experimental results show that the locking angle for woven composite is about 30°. The bending load is smaller than 5 N in the stamping process and decreases with the increase of temperature. The optimal temperature to form the carbon fiber composite is 170 ℃. The die temperature distribution and the deformation of composite sheet were simulated by FEA software ABAQUS. To investigate the fiber movement of carbon woven fabric during stamping, the two-node three-dimension linear Truss unit T2D3 was chosen as the fiber element. The simulation results have a good agreement to the experimental results.

北京首都国际机场周边及机场内地裂缝形变时序InSAR监测

利用StaMPS技术,基于2017~2021年覆盖北京首都国际机场的133景升轨和95景降轨Sentinel-1影像,对机场及周边地面沉降、机场内地裂缝稳定性等进行研究。结果显示,升降轨影像监测结果的一致性较好,在机场南部、温榆河以南区域形成沉降漏斗,漏斗内部最大沉降速率超过40 mm/a,沉降漏斗沿温榆河分布。对升降轨影像监测结果进行内符合精度验证,结果表明,90%以上公共像元的形变速率差位于±10 mm/a之间,证明了升降轨影像监测结果的一致性。特征点时序形变结果表明,金盏乡、富豪村和黄金花园小区附近沉降较严重,最大累积沉降量分别超过250 mm、150 mm和110 mm。从机场整体形变及地裂缝两侧时序和剖线结果均可看出,地裂缝两侧地表的差异形变对比明显,且差异分界线与地裂缝位置较吻合。

基于STPA方法的智能船航行风险评价指标体系构建

针对智能船航行安全风险致因辨识问题,基于STAMP理论,构建基于船员功能替代的智能船系统模型。将船舶航行风险视为系统安全控制问题,运用STPA方法进行风险致因因素分析,在此基础上从组分失效、外部环境干扰和不安全交互三个维度构建智能船航行风险评价指标体系。该指标体系涵盖要素广、风险针对性强,能够科学客观地表征船舶航行系统的安全状态,相关成果为后续开展智能船航行风险定量化评估工作奠定了基础。

基于StaMPS-PS时序InSAR对流层延迟改正方法评估

时序分析是合成孔径雷达干涉测量(InSAR)的一项关键技术,它被广泛应用于监测广阔地区的地表缓慢形变。这种方法能够提供大范围、大面积的形变监测。其中,StaMPS PS方法凭借适用范围广、开源等优点,受到众多学者的使用。但在时序InSAR中,对流层延迟相位会导致形变监测精度的降低,因此,以合肥市为研究区域,分析了经验模型线性改正、GACOS(generic atmospheric correction online service for InSAR)改正和欧洲中期天气预报中心(ECMWF)最新发布的ERA5数据集改正,并对比这3种方法在时序InSAR反演形变速率中的改正效果。通过计算得到研究区的标准差,进行比较分析和验证。其中线性改正、ERA5和GACOS改正后的标准差分别降低了21.71%、16.14%、10.38%。对于合肥区域,这3种方法均可减弱对流层延迟的影响,且精度都有所提高,其中线性改正效果最好,适用性更高,ERA5和GACOS受天气以及地面监测点密度等影响,在该区域改正效果较差。