Showing papers by "Beihang University published in 1992"
TL;DR: In this paper, a simple and exact procedure is presented for linear buckling analysis of laminated conical shells, with orthotropic stretching-bending coupling, under axial compressive load and external pressure.
64 citations
TL;DR: In this paper, a simple and exact procedure for linear buckling analysis of orthotropic conical shells under axial compressive loads and external pressure is presented in the form of a power series in terms of a particularly convenient coordinate system.
42 citations
11 citations
TL;DR: A set of higher order transformation rules are presented that can accommodate large disturbances at transonic speed and are therefore applicable to similar transformations between the high-speed high-pressure compressor and its low-speed model.
Abstract: Improving the performance of high-speed axial compressors through low-speed model compressor testing has proved to be economical and effective (Wisler, 1985). The key to this technique is to design low-speed blade profiles that are aerodynamically similar to their high-speed counterparts. The conventional aerodynamic similarity transformation involves the small disturbance potential flow assumption; therefore, its application is severely limited and generally not used in practical design. In this paper, a set of higher order transformation rules are presented that can accommodate large disturbances at transonic speed and are therefore applicable to similar transformations between the high-speed high-pressure compressor and its low-speed model
9 citations
TL;DR: In this article, the effect of dense spray on drop size measurement by light scattering technology was studied using a Malvern instrument with five duplicated internal mixing airblast atomizers aligned with a laser beam.
Abstract: The effect of dense spray on drop size measurement by light scattering technology was studied using a Malvern instrument with five duplicated internal mixing airblast atomizers aligned with a laser beam. The correction factor data for multiple scattering were obtained. By regression analysis, an empirical equation was obtained that correlated the correction factor as a function of obscuration (OBS), Sauter mean diameter under dilute spray condition (SMD0 ), and drop size distribution parameter for Rosin-Rammler distribution under dilute spray conditions (N0 ). The experimental data showed definitely that the correction factor is not only a function of OBS and SMD0 , as proposed by Dodge, but also is a function of N0 . The correlation fits the experimental data very well, and can be used for practical purposes to correct the data from the Malvern drop sizer at high obscuration conditions.
9 citations
TL;DR: In this article, the microscopic properties of mechanically alloyed powders have been investigated using the 57Fe and 119Sn Mossbauer spectroscopy and the results showed that atomic dispersion and the formation of an amorphous, non-equilibrium solid solution and intermetallic compounds occur during mechanical alloying.
Abstract: The microscopic nature of mechanically alloyed powders has been investigated using the 57Fe and 119Sn Mossbauer spectroscopy. The following alloy systems have been treated by a low-energy ball mill; Al-Fe, Fe-Sn, Ag-Fe, Fe-C and Fe-B. To understand the elementary process of kneading, the repeated rolling method has been employed for the Al-Fe system and compared with the results from the ball-milling method. Pure Fe powders have also been ball-milled in order to understand the effects of heavy deformation using the same conditions and investigated by the 57Fe Mossbauer spectroscopy. Hyperfine interaction parameters obtained show that atomic dispersion and the formation of an amorphous, non-equilibrium solid solution and intermetallic compounds occur during mechanical alloying. From the experimental findings for each powder the characteristic features of the mechanical alloying process have been discussed.
9 citations
TL;DR: In this paper, an efficient oil film damper known as porous squeeze-film damper (PSFD) is developed based on conventional squeeze film Damper (SFD) for more effective and reliable rotor vibration control and especially for improving the blade loss dynamics for rotor support system.
Abstract: An efficient oil film damper known as porous squeeze film damper (PSFD) is developed based on conventional squeeze film damper (SFD) for more effective and reliable rotor vibration control and especially for improving the blade loss dynamics for rotor support system. The permeability of the outer race of PSFD could remarkably improve the squeeze film damping properties. The transient response of a simple rigid rotor and flexible Jeffcott’s rotor supported on PSFD and SFD subjected to sudden unbalance of blade loss are investigated. Time transient simulation show that PSFD could operate effectively under much greater unbalance as compared with SFD, especially under relative large impact loading of blade loss. Furthermore, the effective eccentricities of PSFD with small transmissibilities (T<1.0) extend to a range of e<0.9, and optimum film stiffness and damping distribution within the whole film clearance could be achieved.
8 citations
8 citations
11 Aug 1992
7 citations
TL;DR: In this paper, the thermal stability characteristics of kerosine-type fuels are examined using a heated-tube apparatus which allows independent control of fuel pressure, fuel temperature, tube-wall temperature and fuel flow rate.
Abstract: The thermal stability characteristics of kerosine-type fuels are examined using a heated-tube apparatus which allows independent control of fuel pressure, fuel temperature, tube-wall temperature and fuel flow rate. This method is identified simply as a “constant wall temperature method”. It is different from a previous widely used method, which is identified as a “constant heat flux method”. It is a single-pass system. Rate of deposition on the tube walls are measured by weighing the test tube before and after each test.
6 citations
TL;DR: In this paper, a theoretical analysis for the various kinds of buckling behavior of infinitely long laminated cylindrical shallow shells subjected to lateral uniform pressure is presented, in which first-order shear deformation is included.
TL;DR: In this article, the presence of carboxylic acid provides the enhancement of hole formation by two-color excitation and the thermal stability of the rsulting holes, raising a non-photochemical hole burning with the rearrangement of strong hydrogen bonds in the carboxyl acid.
Abstract: Persistent spectral hole-burning with two-color excitation was performed at 20K for zinc-tetrabenzoporphin with crotonic acid in phenoxy resin. The presence of carboxylic acid provides the enhancement of hole formation by two-color excitation and the thermal stability of the rsulting holes, raising a non-photochemical hole burning with the rearrangement of strong hydrogen bonds in the carboxylic acid
TL;DR: In this article, an analytical method of solution is developed in the delamination analysis of bi-metal glued joints, where all of the basic equations, the conditions of continuity along the interface and the boundary conditions on crack surfaces can be satisfied by the analytical method.
TL;DR: In this paper, a microwave-absorbing composite material was prepared from an electromagnetic loss substance, a resonator and an epoxy resin, which was measured by the use of an HP8510B microwave vector network analyser.
Journal Article•
TL;DR: In this article, the authors study robust strict positive real stabilization criteria for SISO uncertain systems, i.e., considering the problem of when a single controller not only stabilizes a plant with uncertainty under unity-feedback but also enables the closed-loop system to be robustly strictly positive real.
TL;DR: In this article, an asymptotically convergent boundary integral technique is presented for the analytical calculation of the gradients in the solid mechanics problems, which is able not only to calculate the gradient at the point close to or just at the boundary, but also to obtain the higher order derivatives conveniently.
Abstract: An asymptotically convergent boundary integral technique is presented for the analytical calculation of the gradients in the solid mechanics problems. Upon introducing the perturbed trial function for the boundary unknowns into the differentiated integral equations, it is proved that the former intractable hyper-singular integral equations turn out to become asymptotically convergent. The current approach is able not only to calculate the gradients at the point close to or just at the boundary, but also to obtain the higher order derivatives conveniently. Compared with other suggested techniques, the current one has the advantages of efficiency and generality. The demonstrative numerical examples show that the results have very good accuracy compared with the close form solution. Besides, the problem of properly selection of the shape functions to represent the deflection along the free or symmetric side in the Kirchhoff plate bending problems is also discussed.
TL;DR: In this paper, an entropy shock point operator is introduced to account for entropy correction, which has the advantage of simplicity in its mathematical aspects, as does the potential method, and numerical examples in two-and three-dimensional cases show that nonisentropic formulation can simulate inviscid flow better than the traditional potential method.
Abstract: Several points concerning the transonic potential method are briefly reviewed. Comparison of two correction orders—the nonisentropic jump conditions and the vorticity generated behind the shock—shows that the vorticity correction is indeed of higher order. An entropy shock point operator is introduced to account for entropy correction. Numerical examples in two- and three-dimensional cases show that nonisentropic formulation can simulate inviscid flow better than the traditional potential method, and it has the advantage of simplicity in its mathematical aspects, as does the potential method.
TL;DR: A hybrid knowledge engineering development environment called KEDE is described as a powerful toolkit for large AI problems that provides five kinds of knowledge representations: extended frames, semantic nets, procedural knowledge, object-oriented technique, and predicate logic.
Abstract: This paper presents a brief overview of knowledge-based system building tools. Then a hybrid knowledge engineering development environment called KEDE is described as a powerful toolkit for large AI problems. It provides five kinds of knowledge representations: extended frames, semantic nets, procedural knowledge, object-oriented technique, and predicate logic. Correspondingly, it supports: procedure-oriented, data-oriented, object-oriented, and logic-oriented programming. KEDE gains a very powerful inheritance mechanism using frames. It further provides an automatic retrieval technique for processing implicit knowledge, a demon mechanism for firing functions, a message-sending mechanism for activating methods, and two inference engines for backward, forward, and even mixed reasoning. All these facilities are tightly integrated and formed an entirety. KEDE has been implemented in Common Lisp on Sun workstations.
TL;DR: In this article, an inverse design method for transonic airfoil is presented, where the target pressure distribution contains a free parameter that is adjusted during the computation to satisfy the regularity condition derived in this paper.
Abstract: It is known from Lighthill's exact solution of the incompressible inverse problem that in the inverse design problem the surface pressure distribution and the free stream speed cannot both be prescribed independently. This implies the existence of a constraint (regularity condition) on the prescribed pressure distribution. The same constraint exists at compressible speeds. In this paper, an inverse design method for transonic airfoil is presented. In the method, the target pressure distribution contains a free parameter that is adjusted during the computation to satisfy the regularity condition derived in this paper. A few design results are presented here in order to demonstrate the capability of the method.
TL;DR: In this article, the problems in group technology and computer-integrated manufacturing (CIM) are analyzed, and suggestions on part classification and coding, developing computer-aided design (CAD) and production planning (CAPP) in a GT environment, integrating GT-based CAD and CAPP, and the relations between GT, CAPP and computeraided production management (CAPM) are discussed.
Journal Article•
TL;DR: In this article, variable structure control of general multivariable nonlinear systems and its implementation by use of observers are studied and the necessary condition and sufficient condition for the existence of sliding modes arc given.
Abstract: Variable structure control of general multivariable nonlinear systems and its implementation by use of observers are studied in this paper. The necessary condition and sufficient condition for the existence of sliding modes arc given. It is shown that the states of the controlled systems will approach asymptotically the sliding sub-space (or submanifold)globally (or locally, respectively) for linear systems (or a class of nonlinear systems, respectively) if the variable structure control laws arc implemented with state observers.
TL;DR: In this paper, a complex variable-variational method (CVVM) was used to investigate the stress intensity factors (S.I.F) for a double notch edge crack in isotropic or orthotropic plates subjected to pin loads.
TL;DR: In this article, an approximate analytical large deformation method, based on Nadai deformation theory, for calculating the burst speed of aeroengine disks is presented, and the basic equations are developed and the calculation procedures are illustrated.
Abstract: An approximate analytical large deformation method, based on Nadai deformation theory, for calculating the burst speed of aeroengine disks is presented in this paper. The basic equations are developed and the calculation procedures are illustrated. The burst speeds are calculated for some tested disks, and the calculation results are compared with the test results, the differences between two results are shown to be less than 8%. It shows that the new method is both simple and convenient. Therefore, it could be employed in the development of aeroengine disks.Copyright © 1991 by ASME
01 Jan 1992
TL;DR: In this article, the amplitude value and mean value for fatigue stress and fatigue strength are considered as two random variables and a two-dimensional stress-strength interference model is presented, which is better used for fatigue reliability-based design.
Abstract: The amplitude value and mean value for fatigue stress and fatigue strength are considered as two random variables in this paper. The two-dimensional probability distributions of fatigue stress and fatigue strength are established, then a two-dimensional stress-strength interference model is presented. This model will be better used for fatigue reliability-based design.
11 Aug 1992
TL;DR: In this paper, the boundary element method is used to calculate several numberical examples of cur-off wavelength for TE modes in the waveguides, such as dominate TEll in the sectoral waveguide and its slotted antenna, the cut-off wavelengths of dominant modes TEc,, or eH,, in the elliptical waveguide, and others have been calculated also.
Abstract: In this paper, the boundary element method @EM) is used to calculate several numberical examples of cur-off wavelength for TE modes in the waveguides, such as dominate TEll in the sectoral waveguide and its slotted antenna, the cut-off wavelengths of dominant modes TEc,, or eH,, in the elliptical waveguide and others have been calculated also. The change of the cut-off wavelengtk versus the slot width, offsetting, wall thickness and the dimensions of the waveguide are discussed. The method and the program are applicable to all infinite long waveguide system with va
TL;DR: Using the simulation environment of the parallel computer system used in the simulator, the quasi-dynamic task schedule method is presented and can obtain very effective schedulings because of the effect of dynamic conditions, such as the system synchronization, the contention for shared resources, the communication between processors and so on.
01 Jan 1992
TL;DR: A new method for the automatic processing of Young’s fringes obtained from PIV photograph is presented, which is not sensitive to the speckle noise in Young's fringe image, so that a high measuring accuracy could be obtained.
Abstract: A new method for the automatic processing of Young’s fringes obtained from PIV photograph is presented. This processing method is not sensitive to the speckle noise in Young’s fringe image, so that a high measuring accuracy could be obtained, The measuring error of fringe orientation and spacing are less than 0. 5° and 1% respectively. Furthermore, only a less amount of computation is required.
TL;DR: In this paper, the plastic response of a cracked cantilever beam or pipe is studied for degraded nuclear plant piping subjected to large dynaminc loading, and an application of the equations to degraded nuclear power plant piping is presented.