力学学报

MELrING EFFECTS OF ALUMINUM BUAL-SHEET STRUCTURE IN HYPERVELOCITY IMPACT

In this papert melting effects of aluminum dual-sheet structure in hypervelocityimpact are studied experimentally and numerically.With the help of SEM, melted cratersare observed on the backup plate when projectile velocity is larger than 5km/s. As projectilevelocity increases,there are more melted craters on the backup,and perforation failure ofthe backup is concurrently mitigated.Numerical simulations show that,there are two kindsof melting mechanisms,i.e., the shock heating and the plastic work heating.T...

1995, 27(3): 257-266. doi: 10.6052/0459-1879-1995-3-1995-432

PDF

NUMERICAL STUDY OF UNDERWATER EXPLOSION NEAR AIR-WATER SURFACE

The strong blast-wave generated from an intense underwater explosion interactsstrongly with the air-watcrinterfacet forming refractive shock wave and reflective rarefactionwave.These waves are regular initially,but soon develops into irregular pattern. Accompa-nied with this interaction between the blast wave and the free surface,a spray dome formsand develops into a huge hollow water-column. These complex physical features put greatdemands on numerical computation that the numerics should be able to captu...

1995, 27(3): 267-276. doi: 10.6052/0459-1879-1995-3-1995-433

PDF

NEW PROGRESS IN THE INVESTIGATION OF PULSED LASER-INDUCED FAILURE MECHANISM

This paper reveals a new kind of pulsed laser-induced failure mode,which wasexperimentally observed in thin target plate of brass and was named as reverse plugging effect (RPE)by the authors previously.In the test,a pulsed Nd:Glaiss laser beam is used withduration 0.3ms,total energy 30-40J, spot size 2-5mm and particuldrily with a spdtialshape of non-Gaussian type,Theoretical analyses are presented for this newly-observed phenomenon,The present investigation confirms that the laser-induced failurfe mode c...

1995, 27(3): 277-293. doi: 10.6052/0459-1879-1995-3-1995-434

PDF

BEHAVIOUR OF AIR ENTRAINED BY ROLLERS AT THE POINT IF NON-AERATED PLUNGING JET ENTRY

This paper investigates behaviour of air ent rained by rollers at the point ofnon-aerated plunging jet entry. Experimental results indicate that air retained from thepoint of jet entry diffuses along shear layer.Air concentration at the point of entry increocseswith water depth decreasing.There is a form of error function for velocity distribution ofair-water mixture in shear laver. Air concentration is correspondent to normal distribution,in internal and external shear layers respectively. The agreement b...

1995, 27(3): 294-303. doi: 10.6052/0459-1879-1995-3-1995-435

PDF

MECHANICAL-ELECTRIC COUPLING BEHAVIOUR OF A PENNY-SHAPE CRACK IN PIEZOELECTRIC CERAMICS SUBJECTED TO LATERAL SHEARING FORCE

The field equations for three-dimensional problems in transversely isotropicpiezoelectric medium may be reduced to four second order linear partial differential equa-tions,in which the elastic displacement components and electric potential functions areunknowns.In this paper,expressions for displacement components and electric potentialfunctions are derived by using four harmonic functions,they form the so-called general solu-tions of the field equations for three-dimensional problems.As an example,a penny...

1995, 27(3): 303-315. doi: 10.6052/0459-1879-1995-3-1995-436

PDF

FREQUENCY RESPONSE CHARACTERISTIC OF NONLINEAR POLYNOMIAL SYSTEM

For nonlinear polynomial system,the analytical formula of the Multi-dimensionalFrequency Response Function(MFRF)are derived and the pole frequeney set is defined inthis paper.For applications in engineering,the extented transfer functionsin one-frequencydomain are defined basing on the investigation on the response frequency spectral structures.

1995, 27(3): 316-325. doi: 10.6052/0459-1879-1995-3-1995-437

PDF

BOUNDING PROPERTIES OF THE EIGENVALUES PROVIDED BY A QUADRATIC EIGEN-MATRIX FORMULATION

Approximate representation of a transcendental or a non-linear dynamic stiffnessmatrix K(p) by a quadratic eigen-matrix is studied theoretically in this paper, The quadraticmatrix is formed by expressing the elements of K(p)as parabolic functions based on choosingthree fixed values of the eigenparameter. General bounds on the exact eigenvalues of thetranscendental eigenvalue problem provided by the quadratic matrix are shown to exist ifthe three fixed values chosen are below the lowest pole of the transcend...

1995, 27(3): 326-335. doi: 10.6052/0459-1879-1995-3-1995-438

PDF

A SEMI-ANALYTlCAL SOLUTION FOR THERMAL STRESS ANALYSIS OF LAMINATED COMPOSITE CYLINDRICAL SHELLS

The state equation for thermal stress analysis of laminated composite cylindricalshells is derived and a semi-analytical solution is presented by the combination betweenfinite element method and state space control method.By the employing the transfermatrix method,the continuity of interlaminar stresses and displacements is satisfied,andthe variable numbers are reduced greatly.

1995, 27(3): 336-343. doi: 10.6052/0459-1879-1995-3-1995-439

PDF

A NEW HIGH SENSITIVITY TECHNIQUE FOR SHAPE MEASUREMENT

The basic principle of a high sensitivity technique for shape measurement hasbeen described according to the theory of optical interferometry and diffraction. A newmethod is presented to eliminate the item containing coordinate variables in the formula,so that the pure contour fringe pattern can be obtained.The technique has been appliedto measure the depth distribution of a plate surface with extruded marks.Finally,thesensitivity and accuracy have been discussed,and some experimental results are provided.

1995, 27(3): 344-350. doi: 10.6052/0459-1879-1995-3-1995-440

PDF

FINITE ELEMENT SIMULAIIO OF SHEET METAL FORMING PROCESS

A general formulation for sheet metal forming process is developed by means ofthe finite element method.The membrane and bending finite deformations,workpiece andtool contact,frictional stick-slip conditions,bifurcation and post-bifurcation developmentof wrinkles of a sheet metal are analyzed.A nonlinear shell theory in a form of incremen-tal variational principle is employed in the incremental Lagrangian formulation for sheetmaterials of normal anisotropy.Elastic-plastic thin shell finite elements,which fu...

1995, 27(3): 351-364. doi: 10.6052/0459-1879-1995-3-1995-441

PDF

OPTIMAL TOPOLOGY DESIONS OF TRUSSES WITH DISCRETE SIZE VARIABLES SUBJECTED TO MULTIPLE CONSTRAINTS AND LOADING CASES

An algorithm is given for topology optimization of trusses with discrete variablessubjected to multiple constraints and loading cases. The treatment of constraints and strat-egy of removing bars when the topologies change are proposed to avoid singular solutions.The facts that optimal topologies may be affected by different displacement constraints anddiscrete section sets are pointed out in the examples for which satisfactory optimal solutionsare obtained.

1995, 27(3): 365-369. doi: 10.6052/0459-1879-1995-3-1995-442

PDF

SOME NEW CONCEPTs AND PROBLEMS IN STRUCTURAL WAVE CONTROL

In this paper, the concepts and criteria of controllability and degree of control-lability about structural wave domain control are introduced at first,and then the conceptof strutural wave control is drawn,The new defintions of disturbance domain and non dis-turbance dowain are the products of such concepts.Some mathematical criteria and theirproofs are also obtained.

1995, 27(3): 370-373. doi: 10.6052/0459-1879-1995-3-1995-443

PDF

POSTBUCKLING ANALYSIS OF CIRCULAR CYLINDRICAL SHELL UNDER AXIAL COMPRESSION BY FINITE ELEMENT METHOD

Present paper reports a numerical analysis for the postbuckling problem of thecircular cylindrical shell under axial compression using a spline curve shell element which isbased on the convected curvilinear coordinates. An artifice of passing through and evalu-ating bifurcation points and an improvement for the arc-length method are presented.Theload versus edge-short curve obtained is closer to the experiment result than the analyticalsolution and the postbuckling shape obtained is good agreement with the ...

1995, 27(3): 374-379. doi: 10.6052/0459-1879-1995-3-1995-444

PDF

INVESTIGATION ON MEASURING FLEXURE STRENGTH OF SILICON WAFER BY WAFER IMPACT METHOD

A test method for measuring flexure strength of silicon wafer is investigatedwhich adopts circular wafer sample and impact loading.Combining kinetic energy theoremand small deflection sheet theory,We derive the formula calculating flexure strength.Theaccuracy is satisfactory.

1995, 27(3): 380-384. doi: 10.6052/0459-1879-1995-3-1995-445

PDF

1995 Vol. 27, No. 3

NoticeMORE+

Exquisite ArticlesMORE+

Download Center

Author Center