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应用一维瞬态应力波特征线法对交变气动冲击锤的冲击系统进行理论分析,研究冲击部件之间瞬态波的传播及撞击接触面撞击力的变化规律。重点利用非线性动力学分析软件LS-DYNA对交变气动冲击锤的冲击系统模型进行仿真计算,并与理论分析结果对比,验证了仿真模型具有较高的可靠性。研究中计算分析活塞初始冲击速度、工作介质性质对撞击接触面撞击力和活塞冲击反弹速度的影响,得出了活塞瞬态动力特性与活塞初始冲击速度和工作介质性质的关系。研究结果表明,不同物理特性的工作介质对应的气动冲击锤瞬态冲击特性也不同。研究结论为进一步研究气动冲击锤以活塞的冲击特性来判断工作对象的性质提供了理论依据和实际参考。 相似文献
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新型气液联合液压打桩锤动态过程的仿真研究 总被引:1,自引:1,他引:0
液压打桩锤是一种新犁的打桩设备,其动态性能的好坏直接影响打桩质量及打桩效率;根据其工作原理、性能指标和特性要求,运用AMESim软件建立其液压系统仿真模型,并对其主要子模型的建模依据进行说明,运用MATLAB软件对液压缸缓冲部分进行优化设计,计算出相关参数.对液压打桩锤的正常工作过程及其脱桩保护过程进行仿真研究.仿真结果表明该系统可以实现打击能的尤级调节,冲击行程和频率等参数及脱桩保护结构均满足液压打桩锤的性能指标和特性要求,说明该模型的建立比较准确,液压系统设计符合要求. 相似文献
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1 前言液压锤是用于建筑、码头等桩基础施工的预制桩施工机械。随着预制桩施工机械的发展 ,由落锤、气锤、柴油锤 ,发展到了液压锤。目前在国外发达国家已被广泛使用 ,并形成系列化。而我国预制桩的施工机械大多数是用柴油锤进行的 ,柴油锤施工时 ,噪声很大 ,有油烟飞散 ,对城市的环境带来很多的污染 ,给周围的居民带来诸多不便。柴油锤还具有软土地上难于起动的缺点 ,且制造难度较大 ,一旦损坏维修起来非常不便。通过国外对比试验表明 ,液压锤的能量传递效率比柴油锤高得多 ,普通柴油锤其能量传递效率为 30 %~4 0 % ,而液压锤高达 6 0 %… 相似文献
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为解决综采工作面大块煤破碎问题,该文开发了一种采用乳化液作为工作介质的冲击破碎锤,并对其仿真优化。基于低频重载原理设计了蓄能器、控制阀和锤体分置式冲击锤,利用蓄能器、二通插装阀和单向阀等搭建了非连续工作模式液压控制系统,初步确定了冲击破碎锤的主要性能和结构参数。利用AMESim系统仿真软件建立了乳化液冲击破碎锤仿真模型,验证了活塞冲击复位功能,确定了活塞和钎杆的冲击距离,在模型中特别考虑了管路阻力特性。仿真结果表明:蓄能器冲击最大流量达4000 L/min,活塞上腔峰值流量接近7000 L/min,具有超大流量特征,活塞最大冲击速度约10 m/s;采用锥状缓冲结构,可有效降低空打过程活塞与导向套的冲击。乳化液冲击破碎锤为井下大块煤岩破碎提供了一种新的途径。 相似文献
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影响液压锤性能因素的仿真研究 总被引:4,自引:0,他引:4
介绍了一种新型液压锤的工作原理,对液压锤的简化数学模型及考虑所受粘性摩擦力、密封阻力的数学模型进行了仿真研究,并对得出的数据进行了,分析。仿真结果表明:粘性摩擦力降低了BH65液压锤的冲击能,增加了平均输入压力,降低了工作效率,但对冲击频率的影响小大;活塞速度引起的粘性摩擦力比压差引起的粘性摩擦力要大得多,在计算粘性摩擦力时可忽略压差的影响,从而使模型得到简化;密封阻力增加了BH65液压锤的平均输入压力,降低了其冲击能、冲击频率和工作效率。 相似文献
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为研究液压桩锤的工作特性,提高桩锤系统的抗冲击性能,分析了桩锤冲击过程中各组成部件的运动和受力状况.以振动学理论为基础,建立了系统的力学模型以及动力学微分方程;利用模态分析的方法求解该微分方程,得到了桩锤系统的振动规律,通过求导进一步获得了速度、加速度以及各部件之间的相互作用力随时间变化的规律;并应用相关软件对冲击过程... 相似文献
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桩的沉入方法主要有锤击沉桩、振动沉桩、静压沉桩。锤击沉桩一般利用柴油打桩锤沉桩;振动沉桩利用电动或液压振动锤沉桩,振动锤的激振力使桩周土壤液化,降低桩周摩擦力并实现桩体下沉;静压沉桩主要依靠压重克服桩周摩擦力使桩体下沉。 相似文献
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用超声波波速推定基桩平均波速的研究 总被引:3,自引:0,他引:3
尹加德 《振动、测试与诊断》2000,20(4):283-287
针对基桩动测中经常出现的应力波波速难以确定的情况,提出了一种通过测定基桩砼的超声波传播速度间接推定基桩低应变应力波波速的方法,对于特定的基桩而言,超声波波速和动测应力波波速之间存在相关关系,通过一定量的对比试验建立了两者之间的关系式,文中对该方法进行了理论推导和误差分析,并介绍了有关操作技术和工程实例。 相似文献
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《Measurement》2016
Concrete piles are the most common types of foundation structures. Pile damages, such as fractures, cracks, mud intrusion and secondary concrete pouring, are the leading causes of pile structural failure, which may directly result in casualties and economic loss. It is desirable to develop a monitoring system that can detect these pile damages. In this paper, embedded piezoceramic-based smart aggregates transducers along with the active sensing approach are developed to detect common types of pile damages, including crack, partial mud intrusion, secondary pouring, and full mud intrusion, based stress wave measurement. With the active sensing approach, one smart aggregate is used as an actuator to generate a stress wave that will propagate along the pile, and other smart aggregate(s) will measure the propagating wave. All damages, which introduce new interfaces and discontinuities, attenuate the stress wave propagation. The attenuations of the stress waves based on different pile damages were compared by the received sensor signal in time domain. A wavelet packet-based energy analysis was used to develop an energy index to assist the detection of damages. Experimental results demonstrated the feasibility that the proposed approach can detect all four types of common damages associated with concrete piles. 相似文献
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阐述了快速液压夯实机工作原理,建立了快速液压夯实机的动力学模型,并运用波动力学理论对夯实机冲击过程进行了研究,推导出了夯锤夯击时的位移、速度和系统效率函数,最后结合工程试验对夯实效果进行了验证.结果表明:快速液压夯实机具有较好的夯实效果. 相似文献
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本文根据振动理论和应力波理论,严格推导了各种支承刚度下桩的导纳曲线的特点和特征参数。从理论上和实践上说明稳态机械阻抗法和瞬态机械阻抗法测桩原理的一致性,简述了两种方法的各自优点和适用范围. 相似文献
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A. Ameli M. R. Movahhedy 《The International Journal of Advanced Manufacturing Technology》2007,33(1-2):7-17
In this work, a comprehensive study of radial forging process is presented through 2-D axisymmetric and 3-D finite element
simulations while considering internal tube profile. The tube used in this investigation has four internal helical grooves
along its length. The material is modeled with the elastic-plastic behavior, and sliding-sticking friction model is utilized
to model the die-workpiece and mandrel-workpiece contacts. The numerical results in the 2-D case are compared with available
experimental data. Residual stresses in the forged product, stress concentration around the grooves, pressure distribution
on the hammers and mandrel and maximum forging load are studied. The effects of process parameters such as workpiece and die
geometries, percentage of deformation, and workpiece motions on residual stresses and applied pressures on the hammers and
mandrel are investigated. The results provide a valuable insight into the parameters affecting radially forged products and
provide a useful tool for better design of this process. 相似文献
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介绍了仿真软件AMESim的特点,利用AMESim仿真软件对液压破碎锤液压系统进行建模和仿真,分析了其工作参数对液压锤性能的影响,通过调节频率得到液压锤最优参数.仿真结果为以后液压锤的工程应用提供了理论参考. 相似文献
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The wear processes which occur on swing hammers used to comminute an abrasive ore were investigated. The performance of martensitic cast steel and white cast iron hammers was studied to assist in the development of valid simulative wear tests by documentation of the mechanisms by which wear takes place in a repeated impact-abrasion application. The principal mechanism of material loss of the martensitic steel was microspalling, produced by subsurface fracture through a hard brittle white-etching layer developed at the wear surface. Wear of the white cast iron was controlled by the preferential fracture and subsequent spalling of eutectic carbides at the surface, thereby causing the brunt of the ore impacts to be borne by the secondary-carbide-enriched matrix. An explanation of the eutectic carbide fracture process is made based on the interaction of stress waves with the constituents of the microstructure. 相似文献
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Russian Engineering Research - The main types and designs of test systems for riveting hammers are reviewed. A bench test method for riveting hammers is established. The proposed method better... 相似文献