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Improvement in Performance of Shaped Charge using Bimetallic Liner 双金属衬管对聚能药性能的改善
Pub Date : 1900-01-01 DOI: 10.21741/9781644900338-24
S. G. Kulkarni, S. Ingole, M. Rathod, K. M. Rajan, R. Sinha, S. K. Nayak, N. P. N. Prakash, V. Dixit
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引用次数: 0
Influence of Fiber Shape and Water-Binder Ratio on Blast Resistance of PVA Fiber Reinforced Mortar 纤维形状和水胶比对PVA纤维增强砂浆抗爆性能的影响
Pub Date : 1900-01-01 DOI: 10.21741/9781644900338-18
S. Morishima, T. Katayama, Z. Zhang, P. Suprobo, M. Yamaguchi, D. T. Setiamanah, A. Ogawa
Reducing spall damage is a major problem when designing blast-resistant concrete structures. This study was conducted to evaluate the influence of various material factors on the blast resistance of FRCC slabs under contact detonation. The contact detonation tests were carried out on polyvinyl alcohol fiber reinforced mortar (PVAFRM) slabs with four different shapes of PVA fibers and four different water-binder ratios (W/B) of the mortar matrix. Fly ash (type II) was used as admixture and the fluidity of the PVAFRM in its fresh state was varied using a superplasticizer and thickener. As a result, it was obtained that longer fiber is more effective to suppress spall if the fiber diameter is constant, and if the aspect ratio of fiber (lf/df) is constant, finer fibers are more effective to reduce spall. Moreover, the spall-reducing performance is reduced when the W/B value is too high or too low, and it is considered that there is an appropriate value of W/B that depends on the fiber shape. Introduction When designing blast-resistant concrete structures, reducing spall damage is a major problem. Spalling indicates the failure of reinforced concrete (RC) slabs due to contact detonation which caused by the tensile stress waves reflected from the backside of the slab. To preserve human life under such circumstances, the launch of concrete fragments accompanies the spalling needs to be prevented. The authors have verified the good spall-reducing performance of fiber reinforced cementitious composite (FRCC) slabs under contact detonation. However, a designing method for obtaining the required blast-resistant performance of the FRCC members has not been developed yet; one of the reasons for this is that it is difficult to obtain dynamic mechanical properties of FRCCs corresponding to this problem where the dominant strain rate is of the order of 10–10/s. Hence, it may be convenient to consider the spall-reducing performance of FRCC member as a material property of the FRCC. It can be obtained directly based on material factors such as fiber shape, water-binder ratio, and so on. This study was conducted to evaluate the influence of various material factors on the blast resistance of FRCC slabs under contact detonation; therefore, contact detonation tests were carried out on polyvinyl alcohol fiber reinforced mortar (PVAFRM) slabs with four different shapes of PVA fibers and four different water-binder ratios of the mortar matrix. Explosion Shock Waves and High Strain Rate Phenomena Materials Research Forum LLC Materials Research Proceedings 13 (2019) 103-108 https://doi.org/10.21741/9781644900338-18 104 Table 1 Materials used for PVAFRM. Cement Ordinary Portland cement; Density: 3.16 g/cm Admixture Fly ash (Type II); Density: 2.27 g/cm, Specific surface area: 3890 cm/g Fine aggregate Mountain sand; Surface-dried density: 2.56 g/cm, Water absorption: 2.29%, Maximum size: 2.5 mm, Fineness modulus: 2.58 Chemical admixture Superplasticizer (Polycarboxylic-acid
减少碎片损伤是设计抗爆混凝土结构的主要问题。研究了不同材料因素对FRCC板接触爆轰抗爆性能的影响。采用四种不同形状的聚乙烯醇纤维增强砂浆(PVAFRM)和四种不同的砂浆基质水胶比(W/B)对聚乙烯醇纤维增强砂浆(PVAFRM)板进行了接触爆轰试验。采用II型粉煤灰作为外加剂,采用高效减水剂和增稠剂改变PVAFRM在新鲜状态下的流动性。结果表明,在纤维直径一定的情况下,较长的纤维能更好地抑制剥落;在纤维长径比(lf/df)一定的情况下,较细的纤维能更好地抑制剥落。此外,W/B值过高或过低都会降低降屑性能,认为W/B有一个合适的值取决于纤维的形状。在设计抗爆混凝土结构时,减少小块损伤是一个主要问题。剥落是指钢筋混凝土板在接触爆轰作用下发生的破坏,而接触爆轰作用是由混凝土板背面反射的拉应力波引起的。为了在这种情况下保护人类的生命,需要防止混凝土碎片的发射伴随着剥落。试验验证了纤维增强胶凝复合材料(FRCC)板在接触爆轰作用下具有良好的减裂性能。然而,目前还没有一种设计方法来获得所需的FRCC构件的抗爆性能;其中一个原因是,在主导应变速率为10-10 /s数量级的情况下,很难获得相应的frcc动态力学性能。因此,可以方便地将FRCC构件的减碎性能作为FRCC的材料性能来考虑。可根据纤维形状、水胶比等材料因素直接得到。研究了不同材料因素对接触爆轰作用下FRCC板抗爆性能的影响;为此,对聚乙烯醇纤维增强砂浆(PVAFRM)板采用4种不同形状的聚乙烯醇纤维和4种不同的砂浆基质水胶比进行了接触爆轰试验。爆炸激波和高应变率现象材料研究论坛LLC材料研究学报第13期(2019)103-108 https://doi.org/10.21741/9781644900338-18 104表1 PVAFRM所用材料普通硅酸盐水泥;密度:3.16 g/cm掺合料粉煤灰(II型);密度:2.27 g/cm,比表面积:3890 cm/g细骨料山砂;表面干燥密度:2.56 g/cm,吸水率:2.29%,最大粒径:2.5 mm,细度模数:2.58化学外加剂高效减水剂(聚羧酸型);增稠剂(甲基纤维素型)短纤维PVA纤维(I型);密度:1.30 g/cm,尺寸:φ0.1 × 12mm,抗拉强度:1200mpa,拉伸弹性模量:28gpa PVA纤维(II型);密度:1.30 g/cm,尺寸:φ0.2 × 12mm,抗拉强度:975mpa,拉伸弹性模量:27gpa PVA纤维(III型);密度:1.30 g/cm,尺寸:φ0.2 × 18mm,抗拉强度:975mpa,拉伸弹性模量:27gpa PVA纤维(IV型);密度:1.30 g/cm,尺寸:φ0.2 × 24 mm,抗拉强度:975 MPa,抗拉弹性模量:27 GPa表2 PVAFRM的混合配比及静态力学性能。纤维类型Vf [%] W / B [%] FA / B [%] S / B[%]单位重量(公斤/米)Sp / B[%]流γ(kN / m)σB (MPa) E (GPa)ε有限公司(μ)σf (MPa) Bσ
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引用次数: 0
Explosive Welding of Al-MS Plates and its Interface Characterization Al-MS板的爆炸焊接及其界面表征
Pub Date : 1900-01-01 DOI: 10.21741/9781644900338-22
A. Aggarwal, Sd Tyagi, B. B. Sherpa, D. Pal, Sandeep Kumar, A. Upadhyay
Explosive welding is a solid state welding process in which two similar or different materials are claded with the help of explosive energy. The high pressure generated during the process helps to achieve the interatomic metallurgical bonding in the two materials. In this research work, 5 mm aluminum plate was cladded with 20 mm mild steel for plate length of 300 mm x100 mm. Here parallel plate explosive welding set-up configuration using low VoD explosive consisting of mixture of Trimonite-1 and common salt was used. The interface joints were analyzed using optical inverted metallurgical microscope, SEM and Vickers Micro-hardness. It was observed that the value of micro-hardness at the interface was high as compared to the parent materials and decreased as we move away from the interface on both the sides. The optical and the SEM analysis showed straight morphology at most of the welded area. Al-MS plates were successfully welded using this low VoD explosive. Introduction Composite material with good corrosion resistant as well as bond strength is one of the prime needs of any industry for their respective work application. Explosive welding is a well known defined solid state weld process, where two plates are claded with the help of explosive energy in which flyer plate is accelerated towards the base plate and at the interface a very high pressure order of magnitude 10 Mbar is generated followed by jet phenomenon[1]. Jet phenomenon is one of the important conditions for welding which occurs at the collision point in which it removes the oxide layer and provide clean mating surface free of contamination. This is attained by high pressure and kinetic energy deposited during the welding process[2]. Jet process helps atoms of two materials to meet at interatomic distance and form a strong metallurgical bond, where high temperature is obtained followed by rapid cooling in order of 10k/s[3]. Beside this, for weld to occur the pressure should be sufficient high and for sufficient length of time to achieve the bond formation. In explosive welding, pressure generated exceeds the yield strength of both the materials and which act as fluid at the collision point. It is a critical joining process where different parameters such as collision velocity, flyer plate velocity, VoD of explosive plays a very important role in formation of good bond[2] [4]. Many researchers have worked on this process using different material combination with variable explosive properties [5] [6] [7]. Aluminum is a light and corrosion resistant material having vast application in the naval and oil industries. The challenge of joining comes due to difference in chemical, physical properties as well as low solubility of iron in aluminum. Different means have been used to join this combination such as magnetic pressure Explosion Shock Waves and High Strain Rate Phenomena Materials Research Forum LLC Materials Research Proceedings 13 (2019) 128-133 https://doi.org/10.21741/978164490
爆炸焊接是利用爆炸能对两种相似或不同的材料进行熔覆的固态焊接工艺。在此过程中产生的高压有助于实现两种材料的原子间冶金键合。在本次研究工作中,采用5mm铝板包覆20mm低碳钢,板长300mm × 100mm。本文采用低VoD三芒石-1与普通盐混合的炸药进行平行板爆炸焊接装置配置。采用光学倒金相显微镜、扫描电镜和维氏显微硬度对界面接头进行了分析。观察到,与母材相比,界面处的显微硬度值较高,并且随着两侧远离界面而降低。光学和扫描电镜分析表明,焊接区大部分呈直线形貌。利用这种低VoD炸药成功地焊接了Al-MS板。具有良好的耐腐蚀性和结合强度的复合材料是任何行业各自工作应用的主要需求之一。爆炸焊接是一种众所周知的固体焊接工艺,在爆炸能量的帮助下,两块板进行熔覆,其中飞片向基片加速,在界面处产生10毫巴数量级的非常高的压力,随后产生喷射现象[1]。射流现象是焊接的重要条件之一,它发生在碰撞点处,可以清除氧化层,提供干净、无污染的配合表面。这是通过焊接过程中沉积的高压和动能来实现的。射流过程使两种材料的原子在原子间距离相遇并形成牢固的冶金键,在此过程中获得高温,然后以10k/s[3]的速度快速冷却。除此之外,为了发生焊接,压力应该足够高,并在足够长的时间内实现键的形成。在爆炸焊接中,产生的压力超过了材料的屈服强度,并在碰撞点充当流体。碰撞速度、飞片速度、炸药的VoD等参数对形成良好的粘结[2][4]起着至关重要的作用。许多研究人员使用不同的材料组合来研究这一过程,这些材料具有不同的爆炸性能[5][6][7]。铝是一种轻质耐腐蚀材料,在海军和石油工业中有着广泛的应用。由于铁在铝中的化学、物理性质不同以及溶解度低,连接的挑战就来了。已经使用了不同的方法来加入这种组合,例如磁压爆炸冲击波和高应变率现象材料研究论坛LLC材料研究进展13 (2019)128-133 https://doi.org/10.21741/9781644900338-22 129蒸汽焊接[8],扩散焊接[9]超声波焊接[10],但都有一些局限性,并规避了这一点。由于可以在极短的微秒内连接任何尺寸的材料组合,因此采用了爆炸焊接。在本研究中,通过制备标准尺寸试样,通过显微硬度和显微组织分析,研究了铝包覆低碳钢的界面行为。材料和方法在本实验中,铝包覆尺寸分别为300x100x5mm和300x100x20mm的低碳钢,制成单双金属材料。爆炸焊接的系统视图如图1所示。两个盘子保持平行并被距离隔开的地方称为对峙。采用低VoD炸药,由赤铁矿-1与普通盐的混合物组成,VoD在1650 ~ 1800m/s之间。选择铝板作为飞片,是因为其重量轻,耐腐蚀性能好;选择低碳钢作为底板,是因为其抗拉强度好。包覆材料的力学性能如表1所示,所采用的实验参数如表2所示。在本实验中,采用低VoD炸药为平行布置[11]的冶金键合提供必要的能量。爆炸焊接的实际设置如图2 (A)所示,其中爆炸后对地面和对板的冲击如图2 (B)所示,这是焊接过程中产生的能量。处理后形成的双金属板如图2 (C)所示,然后对结合板进行显微硬度和显微组织检查,其中显微硬度是按标准尺寸制备样品,然后借助维氏显微硬度机检测界面附近的硬度变化。图1。 爆炸焊接工艺系统流程图爆炸冲击波与高应变率现象材料研究论坛LLC材料研究论文集13 (2019)128-133 https://doi.org/10.21741/9781644900338-22 130爆炸焊接的整体设置A)爆炸箱放置在板上B)爆炸的影响C)双金属焊接板。为了进行微观结构检查,将样品手工抛光至1μm光洁度。为了研究其内部结构,对样品进行了2%的蚀刻。在金相光学显微镜下对腐蚀试样进行了分析,并采用近界面扫描电镜观察了腐蚀试样的结构行为。为了检查爆炸焊接过程中元素的转移,进行了点阵映射。成功包覆的材料然后进行进一步的应用。表1材料力学性能参数铝(Al)纯低碳钢(MS) 1020硬度值(测量维氏硬度)41 160熔点(开尔文)928 1789密度(Kg/cm) 0.0027 0.00786
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引用次数: 4
Experimental and Theoretical Study of Fragment Safety Distance of Fragmenting Munitions 破片弹药破片安全距离的实验与理论研究
Pub Date : 1900-01-01 DOI: 10.21741/9781644900338-11
S. Singh, H. N. Behera, D. Pal, A. Gupta
The fragment safety distance is an important requirement for test and evaluation of the munition stores in the field trials. It determines the area to be cleared or evacuated before conduct of any trial activity. In this paper, theoretical and experimental work is carried out for establishing the explosive parameters and its interaction with the metallic casing. High explosives are used for controlled fragmentation to generate specific–size-and-weight fragments with lower velocity. Empirical relationship based on high strain rate and Gurney energy criteria were applied and optimized. Two prototypes having two different type explosive filling were fabricated to generate the fragment data. This enables to determine the safety distance useful for conducting trials in small ranges with required safety. The experimental data reveals that 90% fragments of a definite shape and size have been generated. The recorded fragment velocity was of the order of 250 to 400 m/s. Based on these data, safety distance was calculated and found to be about 400 m. Experimentally, fragments were recovered and found up to 130m from the point of burst.
在野战试验中,破片安全距离是弹药库测试和评价的重要要求。在进行任何试验活动之前,它确定要清除或疏散的区域。本文对炸药参数及其与金属壳的相互作用进行了理论和实验研究。烈性炸药用于控制破片,以较低的速度产生特定尺寸和重量的破片。应用基于高应变率和Gurney能量准则的经验关系式进行了优化。为了产生破片数据,制作了两种不同类型炸药填充物的原型。这使我们能够确定安全距离,以便在具有所需安全性的小范围内进行试验。实验数据表明,90%的碎片已经生成了确定的形状和大小。记录的破片速度约为250 ~ 400米/秒。根据这些数据,计算出安全距离约为400米。在实验中,碎片被回收,并在距离爆炸点130米的地方发现。
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引用次数: 0
Deformation Behavior of a Polygonal Tube under Oblique Impact Loading 斜冲击载荷作用下多边形管的变形行为
Pub Date : 1900-01-01 DOI: 10.21741/9781644900338-7
Yohei Shinshi, M. Miyazaki, Keisuke Yokoya
Aluminum tubes are energy-efficient absorbing components and are widely used for framework and reinforcement materials of structures. The effects of the axial length and crosssectional shape on the deformation behavior were investigated. Regarding the axial length, it has changed only to a certain length, and there are few studies on it. This paper deals with the influence of axial length. Also, when an impact is actually applied to the square tube, the impact in the oblique direction must also be taken into consideration. Therefore, the deformation behavior was analyzed by applying impact to the square tube from various angles other than the axial direction. An analysis of the dynamic deformation process of the polygonal tube was made using a finite element method. The results show that the load reached the peak immediately after the weight hit the square tube, then declined gently. The same tendency was obtained even if the axial length was changed. However, as the axial length became longer, the displacement taken to reach the peak load increased. As for the impact in the oblique direction, the peak load was small as compared with the axial direction. The deformation of square tube did not buckle in whole but only partially at any length. Introduction Square tubes have been used for framework and reinforcement members of structures.There are many studies on circular tubes, and deformation behaviors have been studied by static and dynamic compression tests [1]. Previous studies have shown that square tubes have a role of absorbing impact energy by crushing under pressure in the axial direction at the time of a collision [2]. Aluminum alloy has a Young’s modulus that is one-third that of commonly used steel materials, giving it the disadvantage of low rigidity. In addition, the whole buckles become large when thickness is increased, and causing axial compression deformation, which cannot effectively absorb collision energy[3].The tubular bodies with polygonal tubes and cellular cross sections have been studied as a means to effectively absorb energy [4]. Additionally, an influence of axial length on dynamic axially compressed aluminum tubes is being considered [57].It is known that elastic deformation occurs in the entire square tube prior to plastic deformation when the square tube deforms. Since this is periodic and wavy, it seems that the axial length will have a large influence. In a previous study, deformation behaviors up to 500 mm in length have been considered [8]. The purpose of this paper is to discuss, the deformation behavior of dynamic axial compression of an aluminum square tube of axial lengths of 500 mm, 750mm and 1000 mm. Also, when an impact is applied to the tube, the impact in the oblique direction must also be taken into consideration. Therefore, for comparison with the axial compression, deformation behavior of aluminum square tube under oblique impact loading was considered. Explosion Shock Waves and High Strain Rate Pheno
铝管是一种节能吸波材料,广泛应用于结构的框架和加固材料。研究了轴向长度和截面形状对变形行为的影响。轴向长度仅变化为一定长度,研究较少。本文讨论了轴向长度的影响。此外,当实际对方管施加冲击时,还必须考虑斜向的冲击。因此,通过对方管施加除轴向外的不同角度的冲击来分析其变形行为。采用有限元法对多角形管的动态变形过程进行了分析。结果表明:载荷在重物撞击方管后立即达到峰值,然后缓慢下降;即使改变轴向长度,也有相同的趋势。然而,随着轴向长度的增加,达到峰值荷载所需的位移增加。对于斜向冲击,峰值载荷相对于轴向冲击较小。方管的变形在任何长度上都不发生整体屈曲,而只是部分屈曲。方管已广泛应用于结构的框架和配筋构件。对圆管的研究较多,通过静、动压缩试验研究了圆管的变形行为[1]。已有研究表明,方形管在碰撞时具有轴向受压破碎吸收冲击能的作用[2]。铝合金的杨氏模量是常用钢材料的三分之一,因此具有刚性低的缺点。此外,随着厚度的增加,整体屈曲变大,产生轴向压缩变形,不能有效吸收碰撞能量[3]。已经研究了具有多角形管和细胞截面的管状体作为有效吸收能量的手段[4]。此外,还考虑了轴向长度对动态轴向压缩铝管的影响[57]。众所周知,方管变形时,整个方管的弹性变形先于塑性变形。由于这是周期性和波浪式的,因此轴向长度似乎会有很大的影响。在之前的研究中,已经考虑了长度达500mm的变形行为[8]。本文讨论了轴向长度为500mm、750mm和1000mm的铝方管在动态轴压下的变形行为。此外,当对管施加冲击时,还必须考虑斜向的冲击。因此,为了与轴向压缩进行比较,考虑了铝方管在斜向冲击载荷下的变形行为。爆炸激波与高应变率现象材料研究论坛LLC材料研究学报13 (2019)41-46 https://doi.org/10.21741/9781644900338-7 42数值分析通过非线性结构分析程序(Marc 2018)和前后处理程序(Mentat 2018)进行分析。解析模型的示例如图1所示。试样为铝管(A6063-T5)。材料性能如表1所示。对于轴向长度l,分别在20000、30000、40000双线性四节点壳单元上离散方形管(l = 500mm、750mm和1000mm)。在斜向分析中,取重物与方管冲击边缘夹角θ= 10度。分析模型示意图如图2所示。图1方管(l = 500mm)解析模型。图2重物撞击角(θ= 10°)。除在冲击边的轴向外,管边缘上的节点均固定。重量(80 × 80 × 20毫米,15公斤)是一个非离散的三维,八节点,一阶,等参元素。将变形管视为符合von-Mises屈服条件的各向同性材料,由于铝的应变速率影响小于铁等其他材料[9],流变应力-应变关系如式(1)所示。X Y Z θ铝重量
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引用次数: 0
FTMP-Based Quantitative Evaluations for Dynamic Behavior of Dislocation Wall Structures 基于ftmp的位错壁结构动力行为定量评价
Pub Date : 1900-01-01 DOI: 10.21741/9781644900338-15
S. Ihara, T. Hasebe
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引用次数: 0
Observation for the High-Speed Oblique Collision of Metals 金属高速斜碰撞的观测
Pub Date : 1900-01-01 DOI: 10.21741/9781644900338-13
A. Mori
In explosive welding, it is known well that the collision angle and collision velocity are the important parameters to achieve good welding. In addition, generations of a metal jet and the interfacial waves are important for the explosive welding conditions. To know the parameters and the collision conditions, the optical observation and the numerical simulation for the oblique collision using a powder gun were done by the authors. A metal jet was observed clearly by using a powder gun and wavy interface was generated without the intermetallic layer for the reactive materials by controlling the welding conditions. In this investigation, the results of the optical observations and the numerical analysis for similar and dissimilar material combinations were reported. Introduction Explosive welding technique is known well as the welding method to weld strongly for the two metal plates of similar and/or dissimilar material combinations. In explosive welding technique, a metal flyer plate is accelerated by the detonation of explosive and is collided to another metal plate (base plate) with a certain angle at high velocity. A good welding is achieved with generating the interfacial waves in the welded interface and the metal jet at the collision point when the velocity and the angle collided are within the suitable range [1, 2]. Therefore, to achieve the optimal welding conditions for the difficult-to-weld materials, it is necessary to know the parameters and the collision phenomena, such as the metal jet generations and the interfacial waves. The mechanism of interfacial waves and the metal jet generation have been studied theoretically and/or numerically by many researchers [3-5]. Onzawa et al. [6] reported about the characteristics of metal jet generated by the collision of similar and dissimilar metals set on parallel and angular arrangement using a high-speed streak camera. The observation for the metal jet generation is difficult by the optical observation system because the detonation gas spreads out rapidly with the high velocity which is faster than the flying velocity of metal. From the weldability window proposed by Wittman [7] and Deribas [8], claddings same as explosive welding can be obtained when a metal plate collides obliquely at high velocity. To know the inclined collision, same as the phenomena of explosive welding, a powder gun was applied to observe the high-speed oblique collision, which is same as the phenomena of explosive welding, without the influence of detonation gas. And the numerical simulation using SPH solver in ANSYS AUTODYN software was used to understand the material behavior in the high-speed oblique collision, comparing with the experimental results. Explosion Shock Waves and High Strain Rate Phenomena Materials Research Forum LLC Materials Research Proceedings 13 (2019) 74-78 https://doi.org/10.21741/9781644900338-13 75 Experimental Procedure Experimental setup to observe the high-speed oblique collision is shown
在爆炸焊接中,碰撞角和碰撞速度是实现良好焊接的重要参数。此外,金属射流和界面波的生成对爆炸焊接条件也有重要影响。为了了解这些参数和碰撞条件,作者进行了用粉末枪进行斜碰撞的光学观测和数值模拟。用粉末枪观察到明显的金属射流,通过控制焊接条件,反应材料形成无金属间层的波浪形界面。本文报道了相似和不同材料组合的光学观测和数值分析结果。爆炸焊接技术是一种将相似或不同材料组合的两块金属板进行强焊接的焊接方法。在爆炸焊接技术中,金属飞片受炸药的爆炸加速,以一定的速度与另一金属板(底板)形成一定角度的碰撞。当碰撞速度和碰撞角度在适当范围内时,在焊接界面产生界面波,在碰撞点产生金属射流,即可获得良好的焊接效果[1,2]。因此,为了实现难焊材料的最佳焊接条件,有必要了解金属射流生成和界面波等参数和碰撞现象。界面波和金属射流产生的机理已经被许多研究者从理论上和/或数值上进行了研究[3-5]。Onzawa等人[6]利用高速条纹相机研究了相似金属和异种金属在平行和角度排列时碰撞产生的金属射流特性。由于爆轰气体扩散速度快于金属的飞行速度,光学观测系统对金属射流产生的观测存在一定的困难。根据Wittman[7]和der[8]提出的可焊性窗口,在金属板高速斜碰撞时,可以得到与爆炸焊接相同的熔覆层。为了了解与爆炸焊接现象相同的倾斜碰撞,在没有爆轰气体影响的情况下,使用粉末枪观察与爆炸焊接现象相同的高速倾斜碰撞。利用ANSYS AUTODYN软件中的SPH求解器进行数值模拟,了解材料在高速斜碰撞中的行为,并与实验结果进行对比。爆炸冲击波与高应变率现象材料研究论坛LLC材料研究学报第13期(2019)74-78 https://doi.org/10.21741/9781644900338-13 75实验步骤观察高速斜碰撞的实验装置如图1所示。利用熊本大学脉冲功率研究所的粉末炮对金属板进行加速。采用直径为32 mm,厚度为3 mm或5 mm的纯铜镁合金AZ31作为飞片和靶板。飞行板是将超高分子量聚乙烯(UHPE)制成的弹丸结合在一起的。弹丸被设置在火药室一侧的枪管中。在飞片后放置铜重量控制板,控制弹丸的飞行速度。将装入PMMA靶架的靶板以倾斜角度(θ = 7、10、15、20)布置在靶室的靶架上。为了对倾斜碰撞进行光学观察,高速摄像机(HPV-1,岛足公司,能够记录高达100万帧/秒)被放置在目标室的一侧,位于穿过目标室的光线的另一侧。无烟火药和黑火药被放置在火药室里。在靶室处于真空状态后,点燃黑火药。采用显式动力学软件ANSYS AUTODYN,采用二维平面对称性对高速斜碰撞的细节进行数值分析。采用光滑粒子流体力学(SPH)和拉格朗日求解器对靶板和弹体进行了建模。金属板碰撞侧60%厚度部分采用SPH求解器建模,其余40%厚度部分采用拉格朗日量求解。当金属板厚度为5 mm和3 mm时,SPH求解器的粒径和Lagragian求解器的孔径分别固定为0.05 mm和0.03 mm。对每种材料采用了mie - grig - neisen形式的冲击方程和Johnson-Cook强度模型。各方程的材料参数参考文献[9,10]。 6000mm飞翼金属板扳机销φ 32mm φ 40mm炮管靶板靶架靶架θ控制器高速摄像机灯
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引用次数: 1
Impact Joining of Metallic Sheets and Evaluation of its Performance 金属薄板冲击连接及其性能评价
Pub Date : 1900-01-01 DOI: 10.21741/9781644900338-16
M. Nikawa, T. Shibuya, M. Yamashita
Similar or dissimilar metallic sheets were joined at their edges by the original impact joining method developed by one of the authors. Surface layers of both sheet edges activated by high-speed shear are immediately contacted with sliding motion in the joining process. The whole processing time is within a few milliseconds. The materials tested were mild steel and titanium sheets. Drop-weight impact testing machine was used. Joining performance of the fabricated sheets was evaluated by tensile test, etc. The joining was not available all over the thickness between sheets, in which sharp notch was observed near both sheet surfaces. The central portion was successfully joined without cavity. The joined specimen of mild steel and titanium was sliced to remove surfaces with such notch. Fracture occurs at the part of mild steel whose strength is lower, then the joining boundary was not damaged. Introduction It is well known that time and temperature effects have important role in solid state joining by atomic diffusion at elevated temperature. On the other hand, under cold condition, if the surface expansion is relatively large, two metal parts can join at the newly created surface, in which the brittle oxidized surface layer fractures. Joining strength in solid state welding was found to be approximately equal to the normal applied stress during the process in the absence of oxide films for the case of aluminum welded together in 1970 [1]. The film theory of such kind of welding or bonding was established, in which roll bonding was applied in 1983 [2]. Recently the film theory was used to derive a model that quantifies the relevance of these parameters to the weld strength [3]. Cold bonding may have a potential for recycling scrap aluminum [4]. The diffusion bonding is usually achieved by very high compressive stress with large plastic deformation. The shape drastically changes from the initial one and the joining strength also depends on the initial surface condition. Surface treatment is necessary for removal of the dirty surface layer. Experimental results in diffusion bonding were summarized for various metals including superplastic alloys [5]. Joining of different metals were tested [6] and experiments were carried out using super plastic materials [7, 8]. Hot isostatic pressing was also effective for the diffusion bonding of the nickel powder onto alumina tubing [9]. Divergent extrusion was used for bonding of aluminum by means of two opposing punches and finite element simulations was conducted [10]. However, the method requires very special conditions in temperature, atmosphere, surface treatment, etc. and they are very time consuming. One of the authors proposed a novel joining method for sheet metal [11]. The edge of the sheet is joined to another edge, where the sheet thickness is unchanged, because the plates are not plastically compressed. In the present study, the materials are mild steel and pure titanium sheets. Main objectives are t
相似或不同的金属板在其边缘连接由作者之一开发的原始冲击连接方法。在连接过程中,由高速剪切激活的两片板材边缘的表层立即发生滑动运动接触。整个处理时间在几毫秒内。测试的材料是低碳钢和钛板。采用落锤冲击试验机。通过拉伸试验等评价了所制备板材的连接性能。在板材之间的所有厚度上都没有连接,在两个板材表面附近观察到尖锐的缺口。中心部分连接成功,无空腔。将低碳钢与钛的接合试样进行切片,去除表面上的缺口。断裂发生在低碳钢强度较低的部分,连接边界未受到破坏。众所周知,时间和温度效应在原子高温扩散固相连接中起着重要的作用。另一方面,在冷条件下,如果表面膨胀较大,则两个金属部件可以在新形成的表面连接,脆性氧化表面层在此断裂。1970年发现,在没有氧化膜的情况下,固态焊接中的连接强度近似等于铝焊接过程中的正常施加应力[1]。这种焊接或粘接的薄膜理论是在1983年建立的,其中采用了辊焊[2]。最近,薄膜理论被用于导出一个模型,该模型量化了这些参数与焊缝强度的相关性[3]。冷键合可能具有回收废铝的潜力[4]。扩散连接通常是通过非常高的压应力和大的塑性变形来实现的。形状与初始形状相比发生了巨大的变化,连接强度也取决于初始表面条件。表面处理是必要的,以去除脏的表面层。综述了包括超塑性合金在内的各种金属的扩散连接实验结果[5]。对不同金属的连接进行了测试[6],并使用超塑性材料进行了实验[7,8]。热等静压对镍粉在氧化铝管上的扩散键合也是有效的[9]。采用辐散挤压法对铝材进行两对冲接合,并进行有限元模拟[10]。然而,该方法在温度、气氛、表面处理等方面需要非常特殊的条件,而且非常耗时。有作者提出了一种新的钣金连接方法[11]。板材的边缘连接到另一个边缘,其中板材厚度不变,因为板材没有塑料压缩。在本研究中,材料是低碳钢和纯钛板。主要目的是观察工具和材料在装置中的运动,并通过拉伸和弯曲试验,检查爆炸冲击波和高应变率现象materials Research Forum LLC materials Research Proceedings 13 (2019) 91-96 https://doi.org/10.21741/9781644900338-16 92不同材料组成的板材的变形性能。并用元素分析检查了边界。冲击连接装置如图1所示。该装置由落锤的冲击力驱动。质量为22 kg,撞击速度为10 m/s。下片材的左半部分由反冲器支撑,反冲器通过压缩圆管(A6061,直径12mm,壁厚1mm)给予反作用力。A冲头上缘受到冲击,此时开始同步剪切。上剪切面滑动以适应下剪切面。运动在规定的位置停止。该装置安装在预压缩的低弹性橡胶上,避免受力过大造成损坏。试验材料为1.0或3.2 mm厚的低碳钢SPC, 1.0或3.0 mm厚的纯钛TP340。拉伸强度分别为303、317和427、401 MPa。滑动阶段重叠长度变化较大。图1实验设置连接装置中工具与片材的运动通过高速摄像机观察工具与片材的运动,同时进行TP340(上试样)与SPC(下试样)的连接。渐进图如图2所示。在t: 87.7 μs和439 μs时捕获了SPC的剪切变形和断裂。SPC左半段向下移动,TP340剪切断裂后也向下移动。TP340在2456 μs处出现,两种材料的边缘在3018 μs处以规定的重叠长度相互滑动。滑动阶段在3333 μs处终止。
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引用次数: 1
The Combustion and Transition to Detonation of High Pressure Flammable Gas in Closed Spaces Linked with a Narrow Path 高压可燃气体在狭窄通道封闭空间内的燃烧和爆轰过渡
Pub Date : 1900-01-01 DOI: 10.21741/9781644900338-1
Y. Kusuhara, K. Fujiwara, F. Kawashima, S. Maeda, R. Nanba
When flammable gases confined or compressed in closed space such as metal cases or shells accidentally combusted, the deflagration could be generated and building up to detonation might cause intensive explosion. High energy density has been pursued in some industrial products or in some manufacturing processes, while the risk of troubles is increasing. Generally the combustion transitions to detonation in highly turbulent flows and takes some buildup time or propagation length. But in the complicated and closed space geometry such as the structure of compressors there are many interactions among compressive wave and rigid surface, and then the transition to detonation frequently has been observed. The product design considering the transition phenomena and reducing the risk of explosions is required in high energy fields. In this study detonations of flammable gas in the high pressure vessel that has spaces linked with narrow curved path were observed and simulated numerically. A high speed camera was used to observe the flame, and the history data were acquired from pressure gauges. In the simulation, XiFoam mounted in Open FOAM was used as the base code. From the visual comparison between the results of the experiment and the simulation, it was shown that turbulent burning velocity suddenly increases and the pressure exceeds a certain value when combustion transition to detonation. These criteria is useful for the design of interior structure of high pressure facilities.
当密闭或压缩在密闭空间(如金属外壳或外壳)内的可燃气体意外燃烧时,可能产生爆燃,并积聚到爆轰,可能引起剧烈爆炸。在一些工业产品或制造过程中追求高能量密度,但出现故障的风险也在增加。一般来说,在高湍流中燃烧过渡到爆震需要一定的积累时间或传播时间。但在压气机结构等复杂、封闭的空间几何结构中,由于压缩波与刚性面相互作用较多,因而频繁发生爆轰过渡。在高能场中,要求产品设计考虑过渡现象,降低爆炸风险。本文对具有狭窄弯曲路径空间的高压容器内可燃气体的爆轰进行了数值模拟和观察。使用高速摄像机观察火焰,并从压力表获取历史数据。在仿真中,使用安装在Open FOAM中的XiFoam作为基础代码。实验结果与模拟结果的直观对比表明,燃烧过渡到爆轰时,湍流燃烧速度突然增大,压力超过一定值。这些准则对高压设施内部结构的设计具有指导意义。
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引用次数: 0
Collision Behavior in Magnetic Pressure Parallel Seam Welding of Aluminum Sheets 铝板磁压平行缝焊接中的碰撞行为
Pub Date : 1900-01-01 DOI: 10.21741/9781644900338-8
A. Hatta, Y. Kajiro
Magnetic pressure seam welding has attracted attention as a new joining method for aluminum thin plates. Magnetic pressure seam welding is a collision welding process, utilizing electromagnetic force as the acceleration mechanism. The electromagnetic seam welding is a method of abruptly adding a high density magnetic flux around a metal material and utilizing the generated electromagnetic force to deform the thin plate at high speed and pressure welding. This paper deal with the deformation behavior of parallel aluminum seam welded aluminum sheet. Numerical analysis of the dynamic deformation process of the metal plate is performed by the finite element method. The sample used for this analysis is assumed to be a thin plate made of aluminum (A1050-H24, width100mm, thickness 1mm) and composed of quadrilateral elements of plane strain. The experimental results show that the collision speed between the aluminum plates is sufficiently reproduced. The impact point velocity between the aluminum plate surfaces was very high at the initial collision point but decreased continuously during welding. It was also found that the smaller the gap is, the faster the collision point moving speed becomes. Introduction Aluminum has higher electrical conductivity and thermal conductivity than iron, so welding is difficult due to low heating efficiency. In previous studies, there is a report on the magnetic pressure seam welding method [1]-[14]. Magnetic pressure seam welding is a collision welding process similar to explosive welding and utilizes electromagnetic force as an acceleration mechanism. Magnetic pressure seam welding accelerates and collides a certain metal plate (flyer plate) to another stationary metal plate (parent plate) by using electromagnetic force. When an impulse current from a capacitor bank passes through a flat one-turn coil, a magnetic flux is instantaneously generated in the coil. The eddy currents are induced in insulated flyer plate in the coil. In magnetic pressure parallel seam welding, one-turn coils are arranged in parallel. A part of flyer plate along the longitudinal direction of the coil bulged toward a parent plate, then flyer plate collided and was welded to a parent plate. At the time of the high-speed collision, metal jets are emitted in the welding interface of the specimen [7]. The collision point velocity and collision angle are determined by the primary and induced electromagnetic force. True metallic bonding is achieved at the mating interface if contact takes place above an appropriate collision point velocity and collision angle [15]. The purpose of this paper is to discuss, the dynamic deformation behavior of magnetic pressure parallel seam welding of aluminum sheets. Welding principle The welding principle is shown in Fig. 1. Magnetic pressure parallel seam welding uses electromagnetic force to accelerate one metal sheet (flyer plate) against another stationary metal Explosion Shock Waves and High Strain Rate Phenomena
磁压缝焊作为铝薄板的一种新型连接方法,受到了广泛的关注。磁压缝焊是一种以电磁力为加速机构的碰撞焊接工艺。电磁缝焊是在金属材料周围突然加入高密度磁通量,利用产生的电磁力使薄板在高速高压焊接中变形的方法。本文研究了平行铝缝焊接铝板的变形行为。采用有限元法对金属板的动态变形过程进行了数值分析。本分析所用样品假定为由平面应变四边形单元组成的铝制薄板(A1050-H24,宽度100mm,厚度1mm)。实验结果表明,该方法能较好地再现铝板间的碰撞速度。在初始碰撞点,铝板表面之间的碰撞点速度很高,但在焊接过程中,碰撞点速度不断下降。同时发现,间隙越小,碰撞点移动速度越快。铝的导电性和导热性比铁高,加热效率低,焊接困难。在以往的研究中,有关于磁压缝焊方法的报道[1]-[14]。磁压缝焊是一种类似爆炸焊接的碰撞焊接工艺,利用电磁力作为加速机制。磁压缝焊利用电磁力将某一金属板(飞片板)加速碰撞到另一固定金属板(母板)上。当来自电容器组的脉冲电流通过扁平的一匝线圈时,线圈中立即产生磁通。涡流是在线圈中的绝缘飞片中产生的。在磁压并联缝焊中,一匝线圈并联布置。沿线圈纵向部分飞片向母板凸起,飞片与母板发生碰撞焊接。高速碰撞时,试样焊接界面有金属射流喷出[7]。碰撞点速度和碰撞角由主电磁力和感应电磁力决定。如果接触发生在适当的碰撞点速度和碰撞角度之上,则在配合界面上实现真正的金属结合[15]。本文旨在探讨铝板磁压平行缝焊的动态变形行为。焊接原理焊接原理如图1所示。磁压平行缝焊利用电磁力加速一个金属片(飞片)对另一个静止金属爆炸冲击波和高应变率现象材料研究论坛LLC材料研究进展13 (2019)47-52 https://doi.org/10.21741/9781644900338-8 48片(母板)。当突然产生高磁场B并进入金属片时,涡流(电流密度i)穿过金属片。因此,式2的电磁力主要作用在飞片上,并被加速远离线圈,与母板发生快速碰撞[10]。涡流i,电磁力f和焦耳热Q给出如下。κ和B为铝板的电导率和磁通密度。当电磁成形装置的剩余电感较大时,大电流很难通过一匝线圈,因此磁压也变小,难以接合。由于多匝线圈线圈的电感比单匝线圈的电感高,因此可以增大通过线圈的电流,增大磁压。rot i =−κ∂B∂(1)
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引用次数: 0
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Explosion Shock Waves and High Strain Rate Phenomena
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