摘要:

AbstractThis paper presents a novel integral‐equation technique for solving the steady‐state wave‐resistance problem. The free‐surface condition is linearized, but the body condition is satisfied exactly. An integral relation describing the flow inside an arbitrarily truncated internal region is first obtained by applying Green's Theorem, using only the simple source function for an infinite fluid. The internal flow is next matched with eigen expansions in the upstream and downstream outer regions. The radiation condition can be satisfied exactly simply by a proper choice of the solution form in these outer regions. The method is applied to investigate flows about both lifting and non‐lifting two‐dimensional bodies. Agreement with existing results is excellent. The present formulation provides a simple yet rational basis for tackling the practical three‐dimensional ship‐wave problem, in which past workers have encountered considerable difficulties using a complicated free‐surfa

ISSN:0029-5981    

DOI:10.1002/nme.1620140303

出版商:John Wiley&Sons, Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractThe use of contacting components such as gear teeth in mesh and shrink‐fitted shafts is very common in engineering practice. This paper deals with the development of a theoretical method which gives a solution for non‐linear contact problems with irreversibility resulting from stick‐slip phenomenon.The method is based on the finite element method and load incremental theory. The geometrical and the statical boundary conditions on contact surfaces are treated as additional conditions being independent of stiffness equations. As a result, the algorithm of calculation is simplified and only a part of the simultaneous equations related to the contact surfaces is required to be solved instead of the overall stiffness equations at each step. Furthermore, the magnitude of load causing a change in a contact condition of one contact nodepair is taken as a load increment, in analogy with the incremental iterative procedure for elastic‐plastic problems. Therefore, the method provides a general and efficient method for analysis and design of such problems.As illustrative examples, the stick‐slip behaviour of turbo‐alternator end‐bells and other problems are discussed. The calculated results show a reasonable agreement with experimental data and ot

ISSN:0029-5981    

DOI:10.1002/nme.1620140304

出版商:John Wiley&Sons, Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractTwo alternative numerical methods are presented, based on the assumed‐stress hybrid finite element model and the initial‐stress approach, for the elastic–plastic small‐deflection analysis of structures under static loading. The use of the initial‐stress approach results in a set of simultaneous linear algebraic incremental equations to be solved at each loading step, with the elastic stiffness matrix remaining unchanged throughout the loading process and the effects of plasticity included as equivalent element loads. The derivation of these alternative methods differs in the assigning of the incremental stress which satisfies equilibrium; in one case it is the actual stress increment while in the other it is a fictitious stress increment. An equilibrium imbalance correction is included in each of these methods to prevent drifting of the solution during the incremental process. Example solutions are presented which demonstrate the accuracy of the two methods and permit comparisons of the relative efficiencies of the tw

ISSN:0029-5981    

DOI:10.1002/nme.1620140305

出版商:John Wiley&Sons, Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractIn this paper we present an algorithm for adaptively computing smooth piecewise polynomial approximations using restricted range uniform approximations on a finite point set. We also present several numerical examples and offer suggestions for the effective use of this algorithm. We have found the algorithm to be effective for approximating a wide class of functions, either with or without significant levels of noise. Furthermore, since the user of this algorithm actually defines tolerance bands within which the approximation will lie, the algorithm allows the user a great deal of flexibility and control over the shape of the resulting approximations.

ISSN:0029-5981    

DOI:10.1002/nme.1620140306

出版商:John Wiley&Sons, Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractFamilies of two‐and three‐dimensional finite elements are constructed for use in modelling fields with singular derivatives. The elements are complete over linear fields, conform with regular elements, and are easily programmed. A low order exact quadrature rule is also derived for element stiffness calculati

ISSN:0029-5981    

DOI:10.1002/nme.1620140307

出版商:John Wiley&Sons, Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractThe paper summarizes the formulation of a set of computer algorithms for the solution of the three‐dimensional non‐linear Poisson field problem. Results are presented that were obtained by applying algorithms to the analysis of two‐dimensional magnetostatic fields. Scalar and vector potentials were used, and it is shown that the convenient single valued scalar potential associated with the induced sources gives severe accuracy problems in permeable regions. The results become as good as those obtained using vector potential if the scalar potential associated with the total field is used for permeable regions. The combination of two scalar potentials has a significant advantage for three‐dimensional p

ISSN:0029-5981    

DOI:10.1002/nme.1620140308

出版商:John Wiley&Sons, Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractAn algorithm has been developed which automatically calculates the time‐dependent positions of points on the ablating boundaries of two‐dimensional continuum structures with geometrially complex shapes. The structural boundary may consist of ablating and non‐ablating parts. The initial ablating and non‐ablating boundaries are defined by the disjoint union of piecewise linear arcs passing through a finite set of nodal points on the boundary, each defined by a pair of rectangular Cartesian co‐ordinates. For a specified ablation rate, the algorithm calculates successive positions of the boundary points at times specifiec by the user. The algorithm is designed such that it may be easily incorporated, along with an automated mesh generation procedure, into existing finite element codes for transient thermal or stress analysis of structures with ablating boundaries. Two examples are presented from the field of solid rocket

ISSN:0029-5981    

DOI:10.1002/nme.1620140309

出版商:John Wiley&Sons, Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractA general non‐linear interpolation procedure for contouring on any isoparametric surface was presented in a previous article. The method used standard isoparametric interpolation functions and a predictor method for tracing element contour lines. The method presented here extends the previous work by using a predictor‐corrector method to trace element contour lines, thereby making the contouring algorithm more accur

ISSN:0029-5981    

DOI:10.1002/nme.1620140310

出版商:John Wiley&Sons, Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractA physical interpretation of the method—adding αMto the stiffness matrix—used in frequency analysis of unsupported structures is suggested. The proper choice of α is discussed and a relation between angular natural frequencies of structures with and without elastic support is

ISSN:0029-5981    

DOI:10.1002/nme.1620140311

出版商:John Wiley&Sons, Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractA method of introducing general constraint equations into finite element matrix equations is described. The characteristics of the method are that it requires no reordering or condensation of the equations, no large matrix operations, and no increase in the number of unknowns. The method is suitable for application in minicomputer implementations of finite element analysis unless a large number of constraints is to be applied.

ISSN:0029-5981    

DOI:10.1002/nme.1620140312

出版商:John Wiley&Sons, Ltd    

年代:1979

数据来源: WILEY