力学学报

NONLINEAR STABILITY THEORY OF FLOATING BODIES ON VISCOUS LIQUID

The problem of nonlinear stability of equilibrium floating bodies on viscous liquid is discussed by using the stability theory of continuous system. The nonlinear disturbances being considered involve the orientation angles of the floating bodies, location of the centre of mass and the velocity of fluid. The criteria for nonlinear stability, asymptotical stability and instability with respect to various kinds of distance are given.

1990, 22(4): 385-391. doi: 10.6052/0459-1879-1990-4-1995-961

PDF

A NEW GENERALIZED VARIATIONAL PRINCIPLE AND ITS max,min PROPERTY IN THIN PLATE THEORY

A new generalized variational principle in classical thin plate theory is proposed with deflection, transverse shear deformation, curvature, internal moment, transverse shearing force and unknown boundary reaction as argument functions. By applying slight restrictions to the argument functions, the new functional possesses the property of consecutive alternate max min.

1990, 22(4): 392-401. doi: 10.6052/0459-1879-1990-4-1995-962

PDF

STROBOSCOPIC METHOD FOR STRONGLY NONLINEAR SYSTEM

In this paper a new stroboscopic method for strongly nonlinear system and its mathematical foundation are given. By using this method not oaly the existence and futility of the periodic solution can be decided, but the approximate expression of this periodic solution can also be found.

1990, 22(4): 402-412. doi: 10.6052/0459-1879-1990-4-1995-963

PDF

A NEW METHOD OF CALCULATING THE ASYMPTOTIC SOLUTION OF NONLINEAR VIBRATION SYSTEMS——A SIMPLE METHOD OF CALCULATING THECOEFFICIENTS OF NORMAL FORM

Applying nonlinear transformation, the simple method for calculating the coef-ficients of Normal Form by simple algebra has been derived. This method can also be used to solve nonlinear vibration problems. The process are as follows: first, to transform the original (equations to the standard first order differential equations discussed in this paper, then to find the solution of nonlinear vibration equation by simple algebra calculation. This method is easy to learn, and to use.

1990, 22(4): 413-419. doi: 10.6052/0459-1879-1990-4-1995-964

PDF

NONLINEAR DYNAMIC RESPONSE OF THE CIRCULAR PLATES UNDER IMPACT OF A MASS

In the sense of Von Karman large displacement, the governing equation of nonlinear dynamic response of the clamped circular plates under impact of a mass is established by using the virtual displacement principle and Galerkin's method in this paper. The effect of coupling between the impact load and the displacement of. the circular plates is considered. The governing equation is solved by applying the time increment method and the singular perturbation theory, and the asymptotic solutions of nonlinear dyna...

1990, 22(4): 420-428. doi: 10.6052/0459-1879-1990-4-1995-965

PDF

THE IDENTIFICATION OF DYNAMIC PARAMETERS OF STRUCTURE AND THE IMPROVEMENT OF MATHE-MATIC MODEL TO CALCULATE DYNAMIC RESPONSE

This paper contains two main aspects as following 1. The dynamic parameters identified according the data measured from tests. 2. The improved mode-superposition method is suggested in order to obtain more realistic dynamic response.

1990, 22(4): 429-437. doi: 10.6052/0459-1879-1990-4-1995-966

PDF

THE RESPONSE SENSIVIT Y ANALYSIS FOR STRUCTURAL SYSTEMS IN RANDOM EXCITATION

The response covariance matrix equation in non-white noise power spectrum random excitation has been developed. The calculation method of response sensitivity is given. An example calculation is worked out for a missile-trailex system.

1990, 22(4): 438-445. doi: 10.6052/0459-1879-1990-4-1995-967

PDF

NONLOCAL ELASTIC THEORY WITH BODY MOMENTS

In this article, a theory of nonlocal elasticity with body moments is developed on the basis of axiom system of nonlocal continuum field theory. It is shown that there is the nonlocal body moment in the nonlocal elastic solid and the stress asymmetry is the result of the body moment, which is caused by the covalent bonds in material.

1990, 22(4): 446-456. doi: 10.6052/0459-1879-1990-4-1995-968

PDF

A NEW FORMULATED METHOD OF QUASI-COMPATIBLE FINITE ELEMENT AND ITS APPLICATION IN FRACTURE MECHANICS

Based on the local properties of singular field, the displacement pattern of isoparametric element is improved and a new formulated method of quasi-compatible finite element is proposed in this paper. This method can be used to solve various engineering problems containing singular distribution, especially, the singular field existing at the tip of cracks. The singu-lar quasi-compatible element (SQCE) is constructed. The characteristics of the element arc analyzed from various angles and many calculation ex...

1990, 22(4): 457-462. doi: 10.6052/0459-1879-1990-4-1995-969

PDF

SEPARATION FLOW AROUND A CYLINDER IN SHEAR FLOW AT A HIGH REYNOLDS NUMBER

A flow around a circular cylinder in a uniform shear flow at high Reynolds number is numerically investigated by the use of the discrete vortex- approximation. The drag coefficient, lift coefficient, Strouhal number, poaitions of separation point and vortex patterns are given by this calculation. They are reasonable and in Agreement with experimental results.

1990, 22(4): 463-467. doi: 10.6052/0459-1879-1990-4-1995-970

PDF

PROBLEM OF PROPAGATION CRACK SUBJECTED TO τ0t LOADS IN INTERFACES BETWEEN DISSIMILAR MEDIA

An arbitrary continues function of variable t can be uniformly approximated in any closed region by a polynomial, that is by the sum of terms of the form tn. Furthermore any function of t may be represented as a linear superposition of τ0tn. By the theory of complex functions, the problem of propagation crack subjected to τot" loads in interface between dissimilar media can be changed into the Keldysh-Sedov mixd problem of theory of analytic functions. In this paper, the closed solution of this problem is g...

1990, 22(4): 468-472. doi: 10.6052/0459-1879-1990-4-1995-971

PDF

NON-AXISYMMETRIC BUCKLING ANALYSIS OF AN ANNULAR PLATE

The non-axisymmetric buckling and post-buckling of a polar orthotropic annular plate whose edges are clamped and its outer edge w subjected to a uniform radial compres-sive force is analysed by using a shooting method. Eigenvalues are calculated and the existence of bifurcation solutions is discussed. The asymptotic fomulse of the bifurcation solutions are obtained aad the buckling behaviour of the annular plate is analysed.

1990, 22(4): 473-478. doi: 10.6052/0459-1879-1990-4-1995-972

PDF

ON THE CONSTRUCTION OF THE EULEK-BERNOULI BEAM VIA TWO SETS OF MODES AND THE CORRESPONDING FREQUENCIES

In this paper the problem was discussed in which the flextural rigidity and density of the Euler-Bernoulli Beam were solved from some of the displacement modes or the strain modes and the corresponding frequencies of a cantilever or a pinned-pinned beam. The necessary and sufficient conditions for the unique ex istence of a solution to the problem have been set up. An algorithm was proposed and numerical calculations were carried out. Examples and analysis both showed that much better results could be attai...

1990, 22(4): 479-483. doi: 10.6052/0459-1879-1990-4-1995-973

PDF

ON THE VARIATIONAL PRINCIPLES FOR LINEAR THEORY OF DYNAMIC VISCOELASTICITY

A unified new approach is proposed for the systematic Derivation of various simplified Gurtin-type variational principles in linear theory of dynamic viscoelasticity. The prime feature of this approach is the use of an important integral relation and generalized Le-gendre transformations given by the author. With this approach, it; is possible not only to derive the complementary functionals for the five-field, four-field, threefield, two-field and one-field simplified,Gurtin-type variational principles, bu...

1990, 22(4): 484-489. doi: 10.6052/0459-1879-1990-4-1995-974

PDF

CONSERVATION LAWS AND COMPLETENESS THEOREMS FOR LINEAR ELASTIC MATERIALS WITH VOIDS

In this paper the invariance of active quantity under a group of infinitesimal transformation is used to prove the Noether theorem and a class of conservation laws is obtained. And for linear homogeneous elastic materials with voids, the possibility of conservation laws under the scale of transformation is verified. The proof of completeness theorems is also given.

1990, 22(4): 490-494. doi: 10.6052/0459-1879-1990-4-1995-975

PDF

STRESS ANALYSIS OF CRACKED, ADHESIVELY BONDED LAMINATED STRUCTURE

Cracked, adhesively bunded laminated structure is analysed by elastic-plastic finite element. 2-D isoparametric element is used to determine stress in crack and adhesively bunded plate, the stress intensity factors obtained are compared with experimental results. Modified shear element is presented and used to analyse shear strain and stress in adhesive. From analysis, the stress in crack plate tends to be uniform when it is adhesively bunded.

1990, 22(4): 495-499. doi: 10.6052/0459-1879-1990-4-1995-976

PDF

BIAXIAL STRESS CREEP BEHAVIOUR OF HIGH DENSITY POLYETHYLENE

A series of creep tests of HDPE in uniaxial and biaxial stress state were performed on a specially designed biaxial creep machine, a multiple integral function relationship was employed and the stress terms up to third order have been taken into acount. It is found that the corrected multiple integral representation considering the linear viscoelastic range in low stress level agrees very well with test data.

1990, 22(4): 500-505. doi: 10.6052/0459-1879-1990-4-1995-977

PDF

ON THE DYNAMICS OF VARYING STRUCTURE SYSTEM OF RIGID BODIES

This paper has made a detailed study on the dynamics of varying structure system of rigid bodies, offered their mathematical models which are named as nominal, impact, perturbed and verifying equations, discussed the simulation and given an applied example with satisfactory results. Modeling is based on Direct Path Method. The models and methods of this paper are more accurate, more complete and easier to program than most former ones on this topic.

1990, 22(4): 506-512. doi: 10.6052/0459-1879-1990-4-1995-978

PDF

1990 Vol. 22, No. 4

NoticeMORE+

Exquisite ArticlesMORE+

Download Center

Author Center