汽车覆盖件用 5 B003 A 板拉伸实验及成形性的有限元分析

目的研究汽车车身用5B003A板的成形性能。方法在进行单轴拉伸试验的基础上,利用软件eta/DYNAFORM模拟了板成形极限曲线、破裂点应变路径、圆筒拉深过程,并进行了相应变形参数的优化。结果 5B003A板单向拉伸和有限元模拟均出现"交叉颈缩"现象,并且在与轧制呈45°角方向上的冲压性能优于0°和90°方向;5B003A板成形极限破裂点的应变路径漂移倾向较明显,双拉区中均呈ε2=const的应变状态;在与拱顶高实验相近变形条件下,优化得到最佳凸模圆角半径为20 mm时,与极限拉深系数0.43对应的无凸缘拉深的最大板坯尺寸为233 mm,相应最佳压料力为68 kN。结论 5B003A板在45°方向上有较好的冲压性能,且凸模圆角半径、板坯直径、压料力等工艺参数对其拉深成形性能影响较大。     

材料参数对汽车发动机隔热板冲压成型性能影响

本文利用拉伸试验获得的样本数据,通过冲压性能试验和膨胀性实验,分析汽车用铝合金板材料参数和其成形性之间的对应关系,建立了评估铝合金板胀性成形性和拉深性的指标,为发动机隔热板冲压成形合理选材和预测成形性提供可靠的依据,为其它铝制品零件冲压加工中合理选材和预测成形性提供参考性的依据。     

镁合金板拉深及拉胀复合成形性能实验研究

通过实验,研究了镁合金板的拉深以及拉深+胀形复合性能,对这一新材料的冲压变形规律有了一定认识,得到了一些有实用价值的数据:极限拉深系数、壁厚变化、锥杯值以及一些塑性变形现象.     

铝合金 2A16 板材成形极限研究

目的掌握硬铝合金在温热条件下的成形性能变化规律。方法采用结合半球凸模胀形和椭圆液压胀形的复合试验法进行了FLD试验,用最小二乘法拟合试验数据,建立了成形极限预测模型。结果试样均在凸模顶端或附近发生破裂,在室温下网格保持较小的圆形,在210℃和300℃下网格被不同程度的拉长和变大,温度对铝合金2A16的成形性能影响很大,随温度升高,成形极限曲线上移。结论复合胀形试验法具有较高的可靠性与准确性;铝合金2A16在高温下成形性能更好;预测模型较好地表述了极限应变值与温度的关系,根据模型可快速得出FLD。     

超级钢板料冲压性能的拉伸试验研究

将超级钢应用于国产汽车冲压件的生产中不仅可以提高汽车质量,而且可以降低汽车的成本、减小汽车重量、降低能源消耗和减少环境污染.为了在汽车工业中更好地使用超级钢,概述了板材冲压性能的评价指标,介绍了拉伸试验值对板材冲压性能的影响,并对超级钢进行了拉伸试验.研究了超级钢板的硬化指数、塑性应变比、屈服强度、极限强度、均匀延伸率等机械性能,并分析了超级钢板的冲压成形性能,超级刚具有较好的胀形性能、拉深性能、弯曲性能,抗起皱性能等冲压性能,可以广泛地应用于汽车冲压零件生产中.     

基于Oyane韧性断裂准则的板料成形极限预测

本文基于Oyane韧性断裂准则,结合数值模拟方法,预测板料不同应变状态下的极限应变.准则中的材料参数通过单向拉伸和平面应变拉伸试验确定.在模拟胀形试验获得每一时间步应力、应变值的基础上,应用韧性断裂准则预测板料的成形极限.模拟结果表明用韧性断裂准则和数值模拟相结合的方法能成功获得板料的成形极限图.     

纤维金属层合板冲压成形性能研究现状

本文综述了纤维金属层合板(FMLs)在基本力学性能、单向拉伸、弯曲、拉深成形及半球胀形等方面的研究,旨在全面了解FMLs表面处理方式、组分材料厚度、成形工艺条件、模具结构参数、中间纤维铺层方向及铺层方式等因素对材料冲压成形性能的影响,为研发和制造新型轻量化FMLs车身构件进行合理的材料铺层设计、确定优化工艺方案提供依据.指出了建立相应FMLs材料性能预测模型、本构关系模型、成形极限理论、破裂失效判据的必要性和紧迫性.     

换热器用纯钛TA1薄板冷成形性

一、前言 钛的密度低、强度高,具有优异的耐蚀性能,用钛制作板式换热器有很强的竞争力。我国目前有不少厂家用冷压法制造钛板式换热器。换热器的板面有凸起、波纹,形状复杂,在冷态压制过程中容易产生裂纹。钛的价格昂贵,提高冲压件的成品率,降低成本有较大的经济效益。评估板料的成形性试验方法,广泛采用的是单向拉伸试验和模拟试验两种方法。单向拉伸测得的应变硬化指数“n”与厚向异性指数“γ”值是板料成形性的重要指标。n值反映板料成形时抵抗拉伸失稳、变形均匀化的能力。零件在以拉为主的变形方式中,n大的材料应变分布均匀,表面质量好,不易产生裂纹,成形性好。相反,n小的材料变形分布不均匀,表面粗糙,容易产生裂纹。γ值表示板料抵抗变薄的能力,γ愈大,变形时愈不易变薄,对拉深变形有利。但在弯曲时γ大,则外层材料不易变薄,反而容易开裂,因而γ大弯曲性能差。模拟试验按HB640—87。对于国产TA1薄板的冲压性能至今还没有进行系统的研究。本文测试了换热器用TA1板的拉伸性能σ_b,σ_(0.2),δ,n和γ值,还进行了杯突、拉深、     

铝合金复杂曲面薄壁件液压成形技术

介绍了适合于制造铝合金复杂曲面薄壁件的液压成形技术,包括充液拉深、可控径向加压充液拉深和液体凸模拉深。由于充液拉深能提高成形极限,适合于制造铝合金复杂型面零件。可控径向加压充液拉深通过径向压力向内推料,进一步提高了成形极限,适合于成形大高径比筒形件。液体凸模拉深适合于获得深度较大、形状复杂、尤其底部具有小过渡圆角的复杂形状零件。     

AZ31镁合金板锥杯与扩孔成形性能研究

对AZ31镁合金板在20~300℃条件下进行了拉伸力学性能、锥杯及扩孔试验研究。结果表明:随着变形温度的升高,AZ31镁合金板抗拉强度逐渐下降而延伸率不断提高;随着温度升高,锥杯值CCV逐渐减小,300℃时具有较小的锥杯值CCV,获得了较好的“拉深+胀形”复合成形性能;随着温度升高,AZ31镁合金板的扩孔成形性能显著提高。     

Effect of Permeable Crystalline Material on Steel Reinforcement Corrosion of Concrete

Permeable crystalline materialcan permeate into pores and cracks of concrete and catalyze the reaction between Ca(OH) 2and unhydrated cement to generate a great quantity needle non-soluble crystals, which can stop up the pores and cracks of concrete, and increase the impermeability of concrete. This paper reported the results of a study conducted to evaluate steel reinforcement corrosion of concrete specimens uncoated and coated with permeable crystalline material as well as mixed with the permeable crystalline material. The properties evaluated for corrosion test were water impermeability, water absorption, compressive strength and potential. The results of water impermeability, water absorption, compressive strength clearly showed that the permeable crystalline material could prohibit water, any soluble salts and moisture from penetrating the concrete to cause corrosion, leaking, and other problems, and it did increase the compressive strength, which was favorable for protection of corrosion of reinforcing steel. Moreover, it was concluded from the potential-time curve that the steel reinforcement of uncoated specimen was in the state of activation whereas that of other specimens coated and mixed with the permeable crystalline material was in the state of inactivation. Above all, it was indicated that the permeable crystalline materialis very effective to protect the steel reinforcement of concrete from corrosion.     

The Research and Application About "Dry Peeling Off" Technology for Airplane Surface Paint Layer

In this paper, the principle of spurting take off lacquer were introduced; and with orthogonal method the unsaturate polyester was prepared ;it was easy to peel airplane paint layer off with this material and equipment.     

Quality Study of Honeycomb Core Shaping Without Wax Stabilization

Sandwich panels utilizing honeycomb cores result in lightweight, high-strength units that are very rigid. Indeed, they give honeycomb panels the best strength-to-weight ratio of any construction type available. Conventionally, the wax is poured into the cell of the core to strengthen the structure and prevent the core from being crushed during milling. Much time and labor is required to wax, mill, and clean the cores. In this study, the process of pouring wax into the core was skipped. In other words, the cutter directly milled the core. Experiments showed that the compressive strength of the core produced without wax stabilization was only 3% lower than that of cores produced using the traditional method. In addition, the drum peel strengths of cores produced without wax stabilization were 38.4% higher than cores produced using the traditional method, in which residual wax seriously polluted the adhesive. It was also found that eliminating the wax process can reduce costs.     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

In-process thermal treatment of polylactic acid in fused deposition modelling

Polylactic acid (PLA) is one of the most widely used open source fused filament fabrication materials due to its ease of extrusion, biodegradability, and mechanical strength. The mechanical strength of PLA largely depends on the proper growth of its semi-crystalline structure, which can be severely impaired by a low rate of crystallization, particularly in open source printers. This can be further aggravated by the non-uniform thermal distribution of heat that causes improper curing among the extruded beads of the printing material. As a result, PLA printed on open source printers does not achieve the best mechanical properties. This research, for the first time, proposes an additive-free solution implemented through a detailed set of experimentation to improve the curing rate through in-process temperature variations to cure the joints among the beads. Scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy is used to confirm the improvements in the bead joints. This work is conducted in two phases of experiments. In the first phase, a full factorial ANOVA is used to investigate various process parameters and the important variables are used in the second phase to print test specimens in four different sets.     

Investigation of the Corrosion Behaviors of HVOF-Sprayed Carbide Cernet Coatings in Molten Al-Zn-Si Alloy Bath

In continuous hot-dip galvanization process the corrosion and chemical stability of the sink roll in the galvanizing bath are important problem which effects on the quality and productivity. In order to protect the sink roll the carbide cermet and/or ceramic coatings were deposited on the surface of the sink roll. The WC-, Cr3 C2-cermet coatings were deposited by high velocity oxygen fuel (HVOF) spray, respectively. The coating samples were immersed in molten Zn-alloy containing 50 wt % aluminum at 833 K for 24 hr and 144 hr, respectively. The inter-diffusion and inter-reaction of Zn, Al and elements in coating and corrosion behaviors of these coatings were investigated by XRD, SEM and EPMA etc. The corrosion mechanisms of the carbide cermet coatings and ceramic coatings in molten High Al-Zn-alloy were approached.     

Fundamental study of adhesion of ice to cooling solid surface (Discussion on influence of copper oxide layer on ice adhesion force)

In many situations, ice often adheres to a cooling solid surface, frequently causing serious accidents. It is critical to clarify the mechanism of ice adhesion to the cooling surface in order to prevent ice adhesion. In a past study, the shearing stresses of two kinds of test plates with a copper surface having the higher thermal conductivity were measured. The shearing stress corresponds to ice adhesion force. Both shearing stresses were significantly different; however, the cause remains unclear.Therefore, the present study focuses on an oxide layer as the main factor causing the difference of both shearing stresses; the influence of the oxide layer formed on shearing stress was discussed. And in the removal and reformation processes of the oxide layer, the time variation of the shearing stress was clarified. Moreover, the relationship between the state of the copper surface and the shearing stress was also clarified by surface analysis.     

＂Three Transformations＂ and Standardization

During his inspection in Henan Province in May, Chinese President Xi Jinping stressed to ＂push forward the transformation from China Speed to China Quality, from Made in China to Created in China, and from Chinese Products to Chinese Brand＂. The ＂Three Transformations＂ are the specific requirements and goal of China＇s national development in the context that market should play a decisive role in the allocation of resources.     

重塑标准推行格局 推动LED照明的普及（英文）

正When you are enjoying the green,energy-saving and healthy lighting of IKEA LED luminaire,you may not realize that most of IKEA’s LED bulbs are produced by the LED luminaire smart manufacturing system of Hangzhou Zhongwei Photoelectricity CO.,LTD(ZVISION).No longer enclosed in the laboratory,the product standards are brought into the factory workshop and even to the entire production process.Thus,the standards are promoted and applied in a favorable way by enterprises,benefitting consumers with high quality products.     

Chinese Experts Contribute to ISO＇s New Toy Standards

正The international standard,ISO 8124-6,Safety of toys–Part 6:Certain phthalate esters in toys and children’s products,was officially issued by ISO worldwide on August 15.It was the first time for Chinese experts to lead the ISO standard development in toys industry.The standard was drafted by a group of Chinese experts from SAC/TC for toys and relevant Chinese departments and finally completed by a dedicated international group of experts.ISO 8124-6 makes a substantive breakthrough in the aspects of the scope of toys,limitation of plasticizer types,control of test cost,accuracy of test,operation convenience,etc.,offering the operational guidance for toy manufactures and testing laboratories.