共查询到12条相似文献,搜索用时 0 毫秒
1.
A seamless analysis of material behavior incorporating complex geometry and crack- tip modeling is one of greatly interesting
topics in engineering and computational fracture mechanics fields. However, there are still large gaps between the industrial
applications and fundamental academic studies due to a time consuming detailed modeling. In order to resolve this problem,
a numerical method to calculate an energy release rate by virtual crack closure technique was proposed in this paper. Both
free mesh method and finite element method have been utilized and, thereafter, robust local and global elements for various
geometries and boundary conditions were generated. A validity of the proposed method has been demonstrated through a series
of fracture mechanics analyses without tedious crack-tip meshing. 相似文献
2.
K. -S. Park T. -W. Kim H. -Y. Jeong S. -N. Kim 《Journal of Mechanical Science and Technology》2006,20(12):2159-2167
In order to find out a physical quantity which controls the fatigue life of a structure and to predict the fatigue life of
tires, a finite element simulation methodology to use the cracking energy density (CED) and the virtual crack closure technique
(VCCT) was proposed and applied to three different tires of a similar size. CED was calculated to predict the location of
a crack initiation, and VCCT was used to obtain the strain energy release rate (SERR) at the tip of an initiated crack. Finite
element simulations showed that SERR oscillated in the circumferential direction with its minimum occurring just before the
contact zone and its maximum occurring just after the center of the contact zone, and SERR was affected significantly by the
frictional force acting on the crack surface. In addition, a durability test was conducted to measure the fatigue life of
the three tires. The comparison of SERR values with the test data revealed that the fatigue life increased as the amplitude
of SERR decreased or as the R-ratio of SERR increased. 相似文献
3.
In-Kweon Kim 《Journal of Mechanical Science and Technology》1998,12(4):672-679
A simple method, which calculates the mode components of the strain energy release rate of free-edge delaminations in the
laminates, is proposed. The interlaminar stresses are evaluated as an interface moment and interface shear forces that are
obtained from the equilibrium equations at the interface between the adjacent layers. Deformation of an edge-delaminated laminate
is calculated by using a generalized quasi-three dimensional classical lamination theory developed by the author. The analysis
provides closed-form expressions for the three components of the strain energy release rale. The analyses are performed on
[+30/−30/90]s laminates subjected to uniaxial extension, with free-edge delaminations located symmetrically and asymmetrically
with respect to the laminate midplane. Comparison of the results with a finite element solution using the virtual crack closure
technique shows good agreement. The simple nature of this method makes it suitable for primary design analysis for the delaminations
of composite laminates. 相似文献
4.
A constant volume combustion chamber is used to investigate the flame kernel development of gasoline air mixtures under various
ignition systems, ignition energies and spark plugs. Three kinds of ignition systems are designed and assembled, and the ignition
energy is controlled by the variation of the dwell time. Several kinds of spark plugs are also tested. The velocity of flame
propagation is measured by a laser deflection method, and the combustion pressure is analyzed by the heat release rate and
the mass fraction burnt. The results represent that as the ignition energy is increased by enlarging either dwell time or
spark plug gap, the heat release rate and the mass fraction burnt are increased. The electrodes materials and shapes influence
the flame kernel development by changing he transfer efficiency of electrical energy to chemical energy. The diameter of electrodes
also influences the heat release rate and the burnt mass fraction. 相似文献
5.
6.
In this paper the structural performance of aluminium alloy foams have been investigated under both static and dynamic compression loads. Three foam typologies (M-PORE, CYMAT, SCHUNK) in a wide range of density (from 0.14 to 0.75 g/cm3), made by means of different process-routes (melt gas injection, powder metallurgy, investment casting) have been analysed. Foams microstructural characterization has been carried out through morphometric measurements by means of Scanning Electron Microscopy (SEM) and Computed Tomography (CT) and subsequent digital image processing in order to determine average cells size and cell distributions on different section planes. The experimental study aims to assess the strain rate sensitivity and energy absorption capability of commercially available metal foams and to point out the correlation between the mechanical behaviour and the physical and geometrical properties of the foam. It has been found that the specific energy dissipation of foams with similar density can be quite different: for the same volume of foam, average values of 1770, 1780 and 5590 J/kg at 50% nominal compression have been measured on M-PORE (0.19 g/cm3), CYMAT (0.28 g/cm3) and SCHUNK (0.28 g/cm3) foams, respectively. Impact tests showed that the dependence of the plateau stress on strain rate could be considered negligible for M-PORE and CYMAT foams while it is quite remarkable for SCHUNK foams. Moreover, it was found that the peak stress of CYMAT foams has a quite large sensitivity on the loading rate. 相似文献
7.
IC卡式热能表充值系统是专用于IC卡式热能表充值管理的系统,本文从整体上介绍了IC卡式热能表充值系统的设计过程,设计包含读卡器和安装在PC机上的充值系统软件两部分的设计,并选用RS232 Modbus协议作为读卡器和PC机之间通信方式。 相似文献
8.
Kyung-Hoon Shin Changjin Lee Yung H. Yu 《Journal of Mechanical Science and Technology》2005,19(10):1939-1949
Many studies have been conducted to increase regression rate of solid fuel in hybrid rocket. One of them resorts to swirl
flow since it can extend the residence time of oxidizer in the fuel grain. Also, metal wires may lead to increase the regression
rate of solid fuel as shown in solid propellants. In this study, a series of experiments was designed to investigate the enhancement
of regression rate of solid fuel by embedded metal wires and by fuel port grain. And fuel port was designed with a helical
configuration to attempt to induce swirl flow. PMMA with gaseous oxygen is the solid fuel used for investigation. Test results
showed that embedded metal wires turned out to be ineffective method because only 3-4% increases in regression rate were observed.
However, fuel port grain configuration yields higher burning performance of up to 50% increase in regression rate. Also pitch
number as well as total impulse was found to be a design variable. 相似文献
9.
虚拟仪器技术在敏感元件测试系统中的应用 总被引:3,自引:0,他引:3
结合国家重点“九五”科技攻关项目“一体化厚膜高分子温湿度传感器”测试系统的研制,将虚拟仪器技术思想应用在整个开发过程,提出相应的硬件和软件设计结构,并且为虚拟仪器技术思想在诸多测试系统中的应用提供了良好的佐证。 相似文献
10.
11.
In this paper, a new loading method able to subtly control the crack driving force for pressurized blister test was proposed. A theoretical study of the adhesion energy measurement for film/substrate interface using this loading method was presented. Problems considered include solving the exact volume under a circular blister and the elastic strain energy stored in a thin blistering film, determining the work done by the poured colored liquid as external force to the system and the elastic strain energy stored in the compressed air. A new formula of energy release rate was finally presented. A comparison between the work presented here and the existing work was made. 相似文献
12.
In this paper, the sensitivity analysis of yaw rate for a front wheel steering vehicle is performed in the frequency domain.
A two degree of freedom system is used to represent a simple vehicle model in order to derive the system transfer function.
The transfer function is defined between a steering angle input and a yaw rate output. This model shows the simplest lateral
dynamic effect and is useful for understanding of the dynamic characteristics and control aspect of the target system. Vehicle
mass, inertia, cornering stiffiness, and wheel base are selected as design variables. Sensitivity functions of the transfer
function with repect to design variables are derived, and the results show that the response of the yaw rate always has stable
minimum phase characteristics. The objective of this paper is the proposition of a base for re-design and new-design of the
vehicle by checking the yaw rate variations with respect to the design variable change in the frequency domain. Finally, dominant
design variables can be selected based on the sensitivity analysis. 相似文献