共查询到18条相似文献,搜索用时 93 毫秒
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刘宇 《理化检验(物理分册)》2021,57(8):40-43,53
针对核电材料入厂复验无塑性转变温度T NDT与原材料制造厂试验结果不一致的问题,从落锤试验的基本要求出发,结合具体试验操作,对核电用钢铁材料落锤试验的过程控制要点进行了分析,以期提高落锤试验的准确性及试验结果的一致性. 相似文献
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管道的断裂与落锤撕裂试验 总被引:1,自引:0,他引:1
介绍了避免油、气集输管道低应力断裂扩展的上裂原理与速度判据。管道裂纹的扩展速度主要取决于管道钢的转变温度FATT。FATT可由落锤撕裂试验测定。论述了落锤撕裂试验的特点、方法和标准,以及该试验在管道钢材、压力容器钢和船体结构钢薄板上的应用情况。 相似文献
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无塑性转变温度(NDTT)实质的探讨 总被引:1,自引:0,他引:1
通过16Mn钢落锤试样在系列温度下的静载弯曲试验,发现其断裂行为与脆性堆焊焊道及热影响区的存在无关,用于做静态三点弯曲试验的落锤试样表面出与母材相同的冷脆转变特性。落锤试样的堆焊焊道相当于对试样引入一个动态缝。文中提出,NDTT实质是在支载条件下材料冷脆特征温度的反映,若对NDTT做为设计指标,则偏于安全。 相似文献
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反应堆压力容器(RPV)是压水堆核电站最为关键的设备之一,其恶劣的服役环境对RPV钢的材料性能提出了苛刻的要求.综述了RPV钢的低温脆化现象,详细介绍了RPV钢的无延性转变温度、修正无延性转变温度、线弹性断裂韧性要求、ASME曲线法及Master曲线法,最后展望了RPV结构完整性分析评价方法的发展方向. 相似文献
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对20钢、16Mn钢和X70钢不同宽度试样在-80~40℃范围内进行夏比冲击试验,研究了非标准尺寸试样冲击功与标准试样冲击功之间的关系,比较了大小试样韧脆转变温度的不同;把试验结果与ASTM标准、BS标准进行对比,不同尺寸试样的韧脆转变温度漂移程度相差很大。并对上平台冲击功的换算公式做了修正。 相似文献
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为探讨材料延性对无腹筋梁受剪性能的影响,根据高延性混凝土设计理论,考虑纤维抗拉强度、长径比和纤维掺量等因素的影响,进行了4种不同配合比高延性混凝土(HDC)的力学性能试验,并设计了7个高延性混凝土(HDC)无腹筋梁和2个混凝土(RC)梁对比试件,通过静力试验研究材料延性对无腹筋梁的破坏形态、承载力和剪切变形能力的影响。试验结果表明:1)4组HDC试件分别达到不同的延性要求,其等效弯曲韧性可达砂浆试件的50倍,极限拉应变可达普通混凝土的90倍;2) HDC无腹筋梁的承载力可达RC梁的2.36倍,剪切变形能力可达RC梁的3倍以上,均发生具有一定延性的剪拉破坏;3)除剪跨比和纵筋配筋率外,HDC无腹筋梁的受剪承载力和变形能力均随材料延性的提高而增大,在设计中应予以考虑,并可根据工程实际需要选择相应的材料延性需求。 相似文献
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提出采用高延性混凝土改善梁的抗剪性能和变形能力,设计了8个高延性混凝土梁和3个作为对比试件的混凝土梁,并通过静力试验研究不同剪跨比和配筋率高延性混凝土无腹筋梁的破坏形态和破坏机理。高延性混凝土无腹筋梁的剪切破坏形态有挤压破坏、剪压破坏、弯剪破坏和剪拉破坏。试验结果表明:高延性混凝土梁的剪切破坏均表现出一定的延性,与普通混凝土梁的脆性剪切破坏具有明显不同;高延性混凝土梁的剪切裂缝开展缓慢,说明高延性混凝土良好的拉伸应变硬化和多裂缝开展特性能够有效控制剪切裂缝的发展,防止混凝土压碎剥落,显著提高梁的抗剪性能和耐损伤能力;相比普通混凝土无腹筋梁,高延性混凝土无腹筋梁的受剪承载力和变形能力均有明显提高,表明采用高延性混凝土可以显著改善无腹筋梁的脆性剪切破坏模式;剪跨比和纵筋配筋率对高延性混凝土梁的剪切破坏形态和承载力影响较大,其受剪承载力随剪跨比的增大而降低,随配筋率的增大而有所提高。 相似文献
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Fiber reinforced composite materials have been increasingly used as structural material in airplanes, in space applications, and in robot arms because of their high specific stiffness and strength. Structural design and nondestructive test techniques have evolved as increased emphasis has been placed on the durability and damage tolerance of these materials. There are several methods used to detect damaged regions of composite materials. Acoustic emission is one of these. It is a suitable technique for detection of a wide range of micro-structural failures in composite materials.
In this paper, an AE signal analyzer was designed and fabricated with a resonance circuit to extract the specified frequency of an acoustic emission signal. From the tests that were completed, the disturbance noise levels, such as impact or mechanical vibration, of the fabricated AE signal analyzer had a very small value in comparison to those of the conventional AE signal analyzer. Also, the fabricated AE signal analyzer was proven to have generally the same crack detection capabilities as a conventional AE signal analyzer, under static and dynamic tensile tests of the composite materials. 相似文献
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本文以Ly12铝合金为例,讨论了在不同固溶时效条件下,检测面对电导率涡流测试值的影响,并对产生这种影响的原因作了简略的理论分析。 相似文献
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苏静 《中国材料科技与设备》2013,(4):16-16,31
尽管NDT技术具有独特的优越性,但也有其某些缺点,所以不可能用它完全代替传统的检验技术(例如化学分析、金相检验、机械性能检验等),而应当将两者适当地结合起来,互相补充。 相似文献
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Hydration monitoring of cement-based materials with resistivity and ultrasonic methods 总被引:1,自引:0,他引:1
Two test setups, the electrical resistivity and ultrasonic techniques, were used to monitor the hydration process of cement-based
materials. In the electrical resistivity method, a non-contacting device was used. In the ultrasonic method, a wave was transmitted
and measured by the embedded piezoelectric ultrasonic transducers, which had good coupling with the surrounding materials.
The focus of the study was to detect the setting and hardening behaviors of cement paste during the first 7 days of hydration
using the above techniques. Immediate after placing the cement paste into the mould, the measurement started and continued
throughout the hydration process. The obtained resistivity and ultrasonic data were used to interpret the hydration process
of the specimens. The correlation of two techniques was also studied. The results illustrated that both electrical resistivity
and ultrasonic techniques were effective to accurately monitor the hydration of cement pastes. The resistivity method was
able to study both the chemical reaction and physical change during hydration, while ultrasonic method was sensitive to physical
change of cement only. 相似文献
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Q. Y. Lu 《Virtual and Physical Prototyping》2018,13(2):39-48
This paper examines on the obstacles specific to the implementation of non-destructive testing (NDT) techniques in additive manufacturing (AM). The general challenges impeding the adoption of AM for volume production of parts, and the use of NDT techniques to ameliorate some of these challenges are studied. These challenges include the lack of understanding of AM materials, and insufficient standards for the mechanical testing and NDT of additively manufactured parts. An overview on the principle of operation for in-process inspection NDT methods is presented. The techniques include thermography, and acoustic emission testing. The applications of these NDT techniques in AM and their suitability for defects detection of additively manufactured parts are reviewed. The sensitivity, and the advantages and disadvantages of each technique are evaluated. The types of defects, and the detectability of these defects by NDT techniques are assessed. 相似文献
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The present study analyses an aircraft composite fuselage structure manufactured by the Liquid Resin Infusion (LRI) process and subjected to a compressive load. LRI is based on the moulding of high performance composite parts by infusing liquid resin on dry fibres instead of prepreg fabrics or Resin Transfer Moulding (RTM). Actual industrial projects face composite integrated structure issues as a number of structures (stiffeners, …) are more and more integrated onto the skins of aircraft fuselage.A post-buckling test of a composite fuselage representative panel is set up, from numerical results available in previous works. Two stereo Digital Image Correlation (DIC) systems are positioned on each side of the panel, that are aimed at correlating numerical and experimental out-of-plane displacements (corresponding to the skin local buckling displacements of the panel). First, the experimental approach and the test facility are presented. A post-mortem failure analysis is then performed with the help of Non-Destructive Techniques (NDT). X-ray Computed Tomography (CT) measurements and ultrasonic testing (US) techniques are able to explain the failure mechanisms that occured during this post-buckling test. Numerical results are validated by the experimental results. 相似文献