共查询到20条相似文献,搜索用时 93 毫秒
1.
采用示波冲击试验方法,研究了HQ785C钢的夏比V型缺口、线切割缺口和预疲劳裂纹3种类型试样在冲击断裂过程中各部分能量与温度的关系。分析了各部分能量随温度变化的规律。试验结果表明,预疲劳裂纹试样的脆性转变温度比线切割缺口试样和夏比V型缺口试样分别提高约20℃和40℃。 相似文献
2.
金属断裂韧性与缺口试样冲击功间普遍关系与应用 总被引:2,自引:0,他引:2
从冲击功着手,推导出在常温相同断裂机制条件下,缺口试样冲击功(CVN)和断裂韧性KIC间普遍关系。并用回归法求出了40MnVTi微合金钢K^2IC与夏比V型缺口试样冲击功(CVN)间线性回归方程。 相似文献
3.
大小试样冲击功比值变化规律的研究 总被引:2,自引:0,他引:2
通过夏比V型缺口冲击试验,研究了结构钢小尺寸试样的冲击功与标准试样冲击功的比值在系列温度冲击试验中的变化规律,并述评了用等效比值数确定小尺寸试样冲击功指标的问题。 相似文献
4.
通过系列温度冲击试验,采用V,U型缺口的试样,以冲击吸收功,纤维断面率结合断口微观形貌的变化对35CrNi3MoV钢的韧脆转变温度进行测定分析,试验表明:35CrNi3MoV钢韧脆转为温度为-60℃。 相似文献
5.
《理化检验(物理分册)》2017,(2)
冲击韧度是评价材料性能的一个重要指标,同种材料在不同缺口形状下的冲击韧度是不同的。对不同缺口形状的铁基烧结材料进行了室温冲击试验,研究了缺口形状对冲击韧度、冲击断口形貌以及断口附近裂纹微观形貌的影响,试样的缺口形状有半圆型、U型、Ⅰ型、V型和无缺口5种,其中V型缺口的缺口角度又有45°,90°,120°3种。结果表明:无缺口试样的冲击韧度最大,其平均值为9.86J·cm~(-2),远远超出有缺口试样的;半圆型缺口试样的冲击韧度为2.70J·cm~(-2),U型缺口试样的冲击韧度为2.46J·cm~(-2),较半圆型缺口试样的略小;Ⅰ型和3种V型缺口试样的冲击韧度相差甚小,且比U型缺口试样的要低;无缺口试样的冲击断口有明显塑性变形,断口附近产生的裂纹多,分布范围较广;有缺口试样的冲击断口塑性变形不明显,断口附近裂纹少,且分布范围局限在断口处。 相似文献
6.
王承忠 《理化检验(物理分册)》2008,44(6):330-334
4.2国家标准对冲击试样机加工的要求
GB/T229—1994标准规定了V型缺口和U型缺口两大类共计三种标准试样,如图27~29所示,其中U型缺口标准夏比冲击试样又分为两种。 相似文献
7.
范立坤 《理化检验(物理分册)》2014,(8):574-577
对照GB/T 229-2007和ASTM E23-2012c(2014)对V型缺口冲击试样的加工要求,使用有限元模拟计算方法,分析了试样尺寸公差对试样缺口处应力的影响,并利用缺口处的应力评估了尺寸公差对缺口敏感性的影响权重。结果表明:缺口底部高度和缺口角度对试样缺口敏感性的影响权重最大;试样宽度和高度的影响次之,试样长度的影响最小;相比较,ASTM E23-2012c(2014)对V型缺口冲击试样加工尺寸公差的要求比GB/T 229-2007更为合理。 相似文献
8.
Ti—25Al—10Nb—3V—1Mo合金的高周疲劳性能及断裂特征 总被引:1,自引:0,他引:1
实验测定了Ti-25Al-10Nb-3V-1Mo合金650℃下高周疲劳S-N曲线及热暴露后合金的疲劳性能。结果表明,Ti-25Al-10Nb-3V-1Mo合金具有较高的疲劳强度,可以满足转子零件的要求。对比光滑和缺口试样的高周疲劳性能,可以看出该合金缺口敏感程度高,且随着应力水平的增加而增大。 相似文献
9.
管红德 《理化检验(物理分册)》1994,(1)
《理化检验·物理分册》1992年第1期刊登了夏比(V型缺口)冲击试样缺口顶角至背面长度的测量(以下简称《夏比》一文,笔者准备按该文方法加工一块规,但经仔细分析《夏比》一文有以下不妥处,现提出与大家共同商榷。 1 《夏比》中提出的测量注意事项,在实际工作中是较难满足要求的。由于试样V型缺口的顶角要求为45°±2°,试样的顶角为43°±15°,这样实际加工的试样V型缺口的顶角必然大于块规的顶角,这样块规顶角装入试样V型缺口后就不可能靠拢、靠紧,也难保证测量时块规底面至顶角的轴线与试样V型缺口顶角至试样背面棱线的垂直线重合。 为了达到《夏比》中测量注意事项的要求,应当设计一组块规,即43°、45°、47°,使用中根据试样V型缺口的角度来选择相应角度的块规。 2 试样V型缺口顶角结构应为R0.25±0.025mm,因此块规的顶角结构不能是尖角,也应加工成R0.25mm左右的圆角。 3 根据GB2106-80《金属夏比(V型缺口)冲击试验方法》要求,检查试验尺寸用的量具精度不应低于 相似文献
10.
本文研究在13SiMnNiCrMoV结构钢中用尖裂纹的应力强度因子来反映三点弯曲缺口试样的疲劳裂纹萌生规律。当R=0.1f=100Hz,试样尺寸B*W*L=12.5*25*117mm时,缺口名义应力幅的门槛值为△σth=3315ρ^0.352MPa,0.5mm≤ρ≤5mm,△Kth=250ρ0.352MPam门槛值与ρ有关。同时得到缺口裂纹萌生的循环次数Ni与名义应力幅△σ,缺口曲率半径ρ的定量关 相似文献
11.
J. C. Rawers 《Journal of Materials Science》1985,20(6):1929-1933
Charpy samples of low carbon steel were laser-glazed in the V-notch root, resulting in highly modified fracture properties and radially altered crystal structure. Laser-glazing produced two distinct regions: (a) an inner region, next to the bulk material, which was heated above the austenitic transition temperature, was cooled rapidly, and produced a retained austenitic phase, and (b) an outer region, next to the V-notch surface, which was heated above the melting temperature, cooled more slowly, although still very rapidly, and transformed predominantly into the martensite phase. Instrumented impact testing of laser-glazed samples produced fracture energies and fracture toughness values similar to samples prepared by currently accepted ASTM precracking procedures. Laser-glazing is offered as an alternative to existing procedures as an experimental technique for testing fracture toughness samples and, especially, for testing substandard size samples and hard-to-prepare, fracture toughness materials samples. 相似文献
12.
Validation of single-edge V-notch diametral compression fracture toughness test for porous alumina 总被引:1,自引:0,他引:1
The objectives of this study were to validate a single-edge V-notch diametral compression fracture toughness technique for ceramics. Rounded notches and sharpened V-notches were introduced into porous, fine-grained alumina samples, and the fracture toughness results were compared. A theory linking the toughness of the material to the degree of densification fit the fracture toughness results well. The data for the V-notch samples were found to correlate very well with published results for porous alumina. The fracture toughness values were found to be independent of the specimen thickness or notch depth. 相似文献
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The effect of a weld line on the tensile, tensile impact and environmental stress cracking properties of a number of polyethylene (PE) and polypropylene (PP) samples has been investigated. The observed mechanical behaviour has been correlated to material properties, and also to the weld line morphology. PE samples differed in branching, molar mass (Mw) and molar mass distribution (MWD), whereas the PP samples differed in nucleation. The morphology of the weld line formed in injection moulding was analysed by optical microscopy and transmission electron microscopy. The mechanical strength was studied by tensile, tensile impact and constant tensile stress methods. In polyethylene samples with a high Mw, the weld line area was seen through the skin layer to the shear layer, and even down to the beginning of the core layer. The effect of a high Mw on morphological changes was diminished by a broad MWD. Short chain branching limited the morphological change solely to the skin layer. Both PP samples were morphologically rather homogeneous. The weld line created a V-notch on the surface that acted as a crack initiator in mechanical tests and thus reduced the mechanical strength of the weld line samples. The V-notch mainly hid the effect of the morphology on the mechanical properties. © 1998 Chapman & Hall 相似文献
16.
Changzheng Cheng Zhongrong Niu Huanlin Zhou Naman Recho 《Engineering Analysis with Boundary Elements》2009,33(10):1145-1151
A new technique concerning the evaluation of multiple stress singularity orders of a V-notch with the boundary element method is proposed. For linear elastic material, the asymptotic displacement field in a V-notch tip region is expressed as a series expansion with respect to the radial coordinate from the V-notch tip. The series expansion of the asymptotic field is then substituted into the boundary integral equation established on the V-notch. By boundary element discretization, the boundary integral equation is transformed into an eigen-equation with respect to the stress singularity orders. Hence the eigen-values, which are the singularity orders, can be obtained simultaneously by solving the eigen-equation. An evident feature of the present method is that the real and complex singularity orders together with the non-singularity ones can be obtained at the same time. 相似文献
17.
The traditional brittle fracture criteria for V-notched structures are established on the base of the singular stress field
at a V-notch tip where only two singular stress terms are adopted. The non-singular stress terms also play a significant role
in determining the stress and strain fields around a V-notch tip, which in turn could affect the fracture character of V-notched
structures predicted by the fracture mechanics criteria. In this paper, the effect of the non-singular stress on the brittle
fracture properties for the V-notch problem is discussed. Firstly, the stress field around a V-notch tip is described by the
Williams asymptotic expansions. At the same time, the stress field far from the V-notch tip is modeled by the conventional
boundary element method since there is no stress singularity. By the combination of the Williams asymptotic expansions and
the boundary integral equations, the complete stress field at a V-notch tip including several non-singular stress terms can
be obtained. Then, three different brittle fracture criteria are introduced to predict the critical loading and initial crack
propagation direction of V-notched structures under mixed-mode loading. Comparing with the existed experimental results, it
can be found that the degree of accuracy of the predicted results when taking into account the non-singular stress terms is
much higher than the predicted ones neglecting the non-singular stress. 相似文献
18.
The digital gradient sensing (DGS) technique was used to study the stress field at the V-notch tip of polymer materials. First, DGS governing equations at the V-notch tip were deduced using the elastic singular stress fields. Then, theoretical angular deflections of light rays at the V-notch tip were simulated, and the effect of notch angle on the angular deflections was analyzed. Finally, the DGS experiments were conducted, and the angular deflection contours were obtained. The results show that the stress intensity factors at the V-notches extracted from the angular deflections agree well with the results calculated from the finite element method. 相似文献
19.
陈丽凤 《理化检验(物理分册)》2011,(9):568-569,601
针对夏比V型缺口冲击吸收能量的实际测量值明显偏高的情况,调查了夏比冲击试验测试值失准的原因,具体分析了加工方法、加工设备和测量方法对夏比V型缺口冲击试样尺寸及测量精度的影响,以及如何避免冲击吸收能量测试值失准的措施及建议。 相似文献
20.
The paper deals with the development of thermal and residual stress distributions arising from the solidification of a fusion zone near a V-notch tip. A set of numerical solutions of the problem was carried out under the hypothesis of generalized plane strain conditions by means of SYSWELD code. The intensity of the thermal and residual asymptotic stress fields at the sharp V-notch tip was studied for a given V-notch specimen geometry and a predefined fusion zone dimension after simulations on materials with different thermal, mechanical and phase transformation properties and after changing the clamping conditions at the specimen's boundary. The results were compared in terms of the elastic or elastic-plastic notch stress intensity factors giving a contribution to the interpretation of the experimental behaviour of welded joint. 相似文献