环口板加强后T型管节点落锤抗冲击试验研究

针对管节点抗冲击性能比较差的特点,工程常采用在主管和支管相贯区域焊接环口板的方法进行加强。本文以环口板加强和未加强的T型管节点为研究对象,进行落锤抗冲击比较试验研究。通过比较两类管节点的破坏模态和变形发展规律,并分析其冲击力、位移和应变时程曲线以及荷载-位移关系曲线,揭示环口板加强后管节点的抗冲击工作机理和冲击过程中的能量转换规律。研究成果可为正确评估该类管节点抗冲击性能和制定合理加固方法提供可靠的试验数据和设计建议。     

Numerical analysis of temperature profile and weld dimensions in laser ＋ GMAW hybrid welding of aluminum alloy T-joint

The temperature fields in the transient state and weld dimensions in laser ＋ gas metal arc welding （GMAW） hybrid welding of aluminum alloy T-joint for different welding conditions were calculated using the developed heat source model, and the effect of welding speed on them was analyzed. The results show that the temperature field for the first weld pass only shows the feature of GMAW and the one for the second weld pass has the characteristics of both laser welding and GMAW. Welding speed can affect greatly weld dimensions and temperature distribution. When welding speed reaches 3.5 m/min, the fusion zones of two weld passes are separated and the maximum peak temperature of thermal cycle on the workpiece surface decreases largely.     

三通挤压工艺过程的二维弹塑性有限元模拟

三通管接头件是典型的用多向模锻工艺生产的工件，变形十分复杂。本文采用大变形弹塑性有限元理论，准确的接触边界处理技术和畸变网格的重划技术，使用ＡＮＳＹＳ５．０ａ软件经二次开发后，对三通挤压工艺过程及模具进行了二维有限元模拟，为工艺试验提供了可靠的理论依据     

T形接头角接静轴肩搅拌摩擦焊三维流动特征

在T形接头横截面方向预置0.1 mm铜箔作为示踪材料，进行了角接静轴肩搅拌摩擦焊，焊后对T形接头角焊缝进行X-ray 2D透射和X-ray 3D扫描，得到了角焊缝示踪材料的2D流场和3D流场. 在前进侧热塑性材料主要以摩擦剪切为主，材料流动主要向焊接方向流动，并流向前进侧后方，后退侧材料主要以挤压为主，由于T接搅拌针螺纹的存在，使得材料整体向后退侧下方流动. 同时发现，在T接静轴肩后沿附近下方存在示踪材料"堆积区"，表明T接静轴肩对附近的材料塑性流动存在一定的阻碍作用. 根据所获得的观察结果，建立了T形接头角焊缝的三维流动主要特征模型.     

PBL 加劲型矩形钢管混凝土不等宽 T型节点应力集中系数分析

为研究开孔钢板连接件（PBL ）加劲型矩形钢管混凝土 T 型节点的疲劳性能,进行了 T 型节点支管受拉、面内受弯及面外受弯的应力集中系数分析。基于矩形钢管混凝土 T 型节点受拉试验,设计了主管为矩形钢管、矩形钢管混凝土和PB L加劲型矩形钢管混凝土,支管为方钢管的T型节点受拉试件,并采用ABAQUS软件对其进行非线性有限元分析,其中主管钢管宽厚比为27,支主管宽度比为0．4。通过非线性有限元数值模拟,分析热点可能出现位置,并采用二次外推法计算得到支主管的应力集中系数。结果表明：PB L加劲型矩形钢管混凝土节点热点出现位置与矩形钢管节点和矩形钢管混凝土节点一致;与矩形钢管混凝土节点相比,PB L加劲型矩形钢管混凝土节点的应力集中系数显著降低,抗疲劳性能明显提高。     

PVC-U斜三通接头注射模设计

分析了带插口的斜三通接头的结构及工艺特点,介绍了利用Moldflow分析确定浇口设计方案和利用Pro/E设计模具的方法。为了保证产品外观质量,浇口设计在接头处,并采用4个侧浇口以减少充填阻力。所设计的模具结构简单,所得制品外观质量较好。     

填充物、胶膜和Z-pin对复合材料T型接头强度影响对比

为提高复合材料T型接头结构的拉伸强度,对接头中胶膜属性、圆弧区填充物属性和Z-pin增强三种结构参数对T型接头强度的影响进行了研究。设计了两种不同胶膜属性、两种不同填充材料和有无Z-pin的同尺寸试验件,完成拉伸试验,测得极限位移和极限拉伸强度,并进行了对比分析,同时研究了不同T型接头的损伤演化过程。结果表明：J299胶膜复合材料T型接头的极限位移和极限载荷相比于J116B胶膜分别提高了57.8%和64.7%;ZXC195增强芯复合材料T型接头的极限位移和极限载荷相比于单向带材料分别提高了51.7%和30.3%;Z-pin钉对复合材料T型接头的极限位移和极限载荷分别提高了190.8%和31.9%。三种结构参数均只影响接头的极限载荷和极限位移的大小,接头的整体刚度没有改变。胶膜属性对接头极限载荷的提高影响最大,而Z-pin对接头的极限位移提高影响最大。     

T形圆管相贯节点的低周往复受力性能研究

通过对T形相贯节点在低周往复荷载作用下的试验,研究该节点的破坏形式、受力性能,同时对该节点进行有限元模拟分析,其结果与试验结果较为吻合。分析结果表明:T形圆管相贯节点具有较好的延性。T形相贯节点的滞回曲线稳定饱满,具有较为理想的抗震耗能作用。     

覆板加强的方钢管T形节点轴向滞回性能试验研究

为研究采用覆板加强的冷弯方钢管T形节点的轴向滞回性能,对2组支管与主管的截面宽度比β分别为0.4和0.8的方钢管直接焊接节点和采用覆板加强的方钢管T形节点进行了轴向往复加载试验。详细介绍了试验节点的设计、试验过程及破坏形态,并对节点试件的滞回曲线、骨架曲线、耗能和延性等性能进行了分析。试验中,试验节点经历了主管屈服、初始开裂、裂纹闭合、裂缝扩展、裂缝贯通五个主要阶段,但各试件的开裂位置并不相同。加强覆板阻止了裂缝向主管管壁发展,有效避免了主管管壁的撕裂破坏,使开裂后支管的受压荷载继续上升,因而节点开裂后受拉能力较未加强节点的好。支管与主管截面宽度比越小,试件的耗能能力和延性越好。但覆板加强处理降低了试件的耗能能力,且支管与主管宽度比越小其耗能能力的降低越明显。受拉裂缝会降低试件的延性,故轴拉循环的延性较对应的轴压循环的差。在β=0.8时,覆板加强对试件的抗震延性有所改善,但β=0.4时加强节点试件的位移延性系数低于未加强节点。覆板加强节点在支管轴向往复荷载作用下的拉压不均衡问题应引起重视。     

Numerical analysis of adhesively bonded T-joints with structural sandwiches and study of design parameters

Adhesively bonded T-joints are extensively used in assembling sandwich structures. The advantage of adhesive bonded joints over bolted or riveted joints is that the use of fastener holes in mechanical joints inherently results in micro and local damages to the composite laminate during their fabrication. One type of adhesive joint in such structures is the T-joint between sandwich panels. The aim of this research paper is to study, by numerical analysis, the effect of fillet geometry and core material of sandwich panels on the performance of T-joints. The base angle of the core triangle (fillet) is the most important geometry parameter of the triangular T-joint. Nine geometrical models with different base angles of the core triangle are made to investigate the effect of the base angle on the performance of the T-joints. It should be mentioned that the base angle in the triangular foam is changed, so that the final volume of the filler is kept constant in all the cases. Different foams with different stiffness are used to model the core of the panels to study the effect of the core material of sandwich panels. To model the adhesive between joint components, contact elements and cohesive zone material models are used. Therefore, failure of adhesive and separation of joint elements can be modeled. Damage and core shear failure of the base panel are modeled by using a written macro-code in the ANSYS finite element method (FEM) program. The ultimate strength of the joint in each case is calculated by modeling adhesive failure and core shear failure of the sandwich panels. Finally, the results of FEM are validated by experimental results available in the literature. In general, the failure load predicted by the FEM is within 5% of the experimental results. The best angle of the core triangle was found to be 45°. Also, the results showed that by changing the core material of the sandwich panel, the joint failure load is also changed.