摘要:

AbstractA finite element formulation is presented for treatment of the mechanical interaction between a rod‐like object and a continuous medium, as occurs, for example, between reinforcing steel and surrounding concrete. An impenetrability constraint restricts the rod's lateral motion relative to the continuum, while an accompanying constraint allows axial slip subject to a release criterion. Satisfaction of these constraints is enforced via application of penalty and augmented Lagrangian regularizations. The proposed implementation is suitable for both static and dynamic implicit equation solving schemes, making it useful for a wide range of problem

ISSN:0029-5981    

DOI:10.1002/nme.1620370102

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractA triangular flat facet finite element for the analysis of general thin shells is presented. It is constructed from simple cubic polynomial displacement fields using a complete set of six degrees of freedom at the element vertices, thereby easily meeting the requirements of standard commercial computer programs. The theoretical development is based on a variational principle which allows a direct formulation of the element stiffness matrix, without inversion, and which permits considerable simplification of the mathematical formulation. The new flat facet element generally produces more accurate numerical results than those obtained in earlier related work. It also offers a possible basis for constructing an improved curved approximation to a shell surface and for further developments in connection with applications involving geometric non‐linearit

ISSN:0029-5981    

DOI:10.1002/nme.1620370103

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractA pseudo‐transient (static) linear, geometric, material and combined geometric and material non‐linear analyses of composite laminates are presented. A nine‐noded isoparametric quadrilateral finite element belonging to the Lagrangiar family is used in space discretization. An explicit time marching scheme is employed for time integration of the resulting discrete ordinary differential equations with the special forms of diagonal fictitious mass and/or damping matrices. Elasto‐plastic material behaviour is incorporated using the flow theory of plasticity. In particular, a modified version of Hill's initial yield criterion is used in which anisotropy parameters of plasticity are introduced. The shear deformation is accounted for by assuming a constant transverse shear strain across the thickness of the laminate and the geometric non‐linearity is considered in the sense of von Karman strains. The layered element approach is adopted for the treatment of plastic behaviour through the thickness. A wide range of numerical examples is presented to demonstrate the validity and efficiency of the present approach. The results for combined non‐linearity are also presented. The variety of results presented here, which are based on realistic material properties of often‐used advanced laminated composite plates, and especially those for combined non‐linear analysis, should serve as a reference for future

ISSN:0029-5981    

DOI:10.1002/nme.1620370104

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractThe tangent operator and design sensitivity expressions for non‐linear elastica subject to frictionless unilateral contact are derived and computed via the finite element method. The sensitivity computations are then combined with a numerical programming package to create an optimal design environment. To exemplify the optimal design environment, a beam's contact surface is contoured to minimize bending stress. This work combines the research on the sensitivity analysis of non‐linear elastic bodies subject to constraints, finite strain non‐linear elastic beam analysis and contact analyses. The analysis is valid for any smooth contact surface; and specialized for the case in which the surface is represented by a cubic spline. The direct differentiation method is utilized to perform the sensitivity analysis. In an example problem, the sensitivity analysis is verified by finite difference computations and then combined with a numerical optimization program to design the stop profile of a

ISSN:0029-5981    

DOI:10.1002/nme.1620370105

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractA co‐rotational finite element formulation for the dynamic analysis of planar Euler beam is presented. Both the internal nodal forces due to deformation and the inertia nodal forces are systematically derived by consistent linearization of the fully geometrically non‐linear beam theory using the d'Alembert principle and the virtual work principle. Due to the consideration of the exact kinematics of Euler beam, some velocity coupling terms are obtained in the inertia nodal forces. An incremental‐iterative method based on the Newmark direct integration method and the Newton–Raphson method is employed here for the solution of the non‐linear dynamic equilibrium equations. Numerical examples are presented to investigate the effect of the velocity coupling terms on the dynamic response of the beam s

ISSN:0029-5981    

DOI:10.1002/nme.1620370106

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractA variationally coupled finite element–boundary element method is developed for transient problems. A single variational statement is obtained for the entire domain and the unknown tractions, which may be discontinuous on the interface and are often a source of difficulties, are eliminated. Moreover, no interface conditions need be taken into consideration at the level of the discretized equation. The discrete equations for the coupled system can be obtained directly without any intermediate steps. The method generalizes a coupling method previously developed by the authors for statics. Numerical examples show that the solutions obtained by the present method agree very well with those obtained by analytical solution

ISSN:0029-5981    

DOI:10.1002/nme.1620370107

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractA boundary integral equation formulation for thin bodies which uses CBIE (conventional BIE) only is well known to be degenerate. A mixed formulation for a thin rigid scatterer which combines CBIE and HBIE (hypersingular BIE) is motivated by examining the discretized form of the integral equations, and this formulation is shown to be non‐degenerate for thin non‐rigid inclusion problems. A near‐singular integration procedure, useful for singular integrals as well, is presented. Finally, numerical examples for acoustic wave scattering from rigid and soft scatterers are pres

ISSN:0029-5981    

DOI:10.1002/nme.1620370108

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractP‐version finite elements based on higher‐order theory are developed for the two‐dimensional modelling of general bending and cylindrical bending of thin‐to‐thick laminated composite plates. In the case of general laminated plate elements, three displacement fields are used. In the special case of cylindrically bent laminated plate elements, two displacement fields are needed. In each case the displacement is expressed as the product of two functions—one in terms of out‐of‐plane co‐ordinates alone and the other in terms of in‐plane co‐ordinates. The shape functions used to build the displacement fields are based on integral of Legendre' polynomials. The quality and performance of the elements are evaluated in terms of convergence characteristics of displacements and stresses. The predicted response quantities are compared with those available in the published literature based on analytical as well as conventional

ISSN:0029-5981    

DOI:10.1002/nme.1620370109

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractThe subspace iteration method is widely used for the computation of a few smallest eigenvalues and the corresponding eigenvectors of large eigenproblems. Under certain conditions, this method exhibits slow convergence. For improving the convergence of the method, a few acceleration techniques are already available in the literature. In this paper, yet another method is presented. The method has been applied for the computation of a few smallest eigenpairs of some typical eigenprobiems. The results indicate that the acceleration method is efficient for large eigenproblems. Simplicity, ease of computer implementation, absence of parameters whose values are to be chosen based on experience and effectiveness for large problems are the attractive features of the proposed method.

ISSN:0029-5981    

DOI:10.1002/nme.1620370110

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractThis paper presents a state space model and an optimal design scheme for non‐isothermal metal forming processes. By selecting nodal velocity and temperature as the state variables, a non‐isothermal state equation with coupled deformation and thermal terms is established. Based on this state space model, a control design scheme is developed to obtain the optimal die velocity and initial die temperature which will ensure that the effective strain‐rate and temperature satisfy the design requirements. A titanium alloy engine disk forging is used to demonstrate two design examples. The results show that the proposed model and design scheme behave well for different design require

ISSN:0029-5981    

DOI:10.1002/nme.1620370111

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY