1,721,085 research outputs found
Analysis of beam cross section response accounting for large strains and plasticity
Full text linkThe nonlinear response of straight, constant cross section of beams is investigated by means of a semi-analytical approach. The three dimensional displacement field is approximated, for a given cross section, using a FE element discretization on the section combined with a Taylor expansion in the beam axial direction. This allows to compute the beam cross section deformation as a function of the stress resultant and moment resultant, without the need to solve a three dimensional model, still allowing to account for complex three-dimensional constitutive laws
A two-level nonlinear beam analysis method
Full text linkThe nonlinear response of straight, constant cross-section beams is investigated by means of a two-level finite element solution procedure. The higher level model is built starting from the Hellinger–Reissner principle, with the normal stress resultant and moment resultant as additional unknowns field beside the beam reference line position and orientation field. A lower-level nonlinear cross-section problem is defined for each integration point. The two-level models are linked together by the normal stress resultant and moment resultant, in one direction, and by the variation of the complementary strain energy in the other: the cross-section level do deform in such a way that the normal stress resultant and moment resultant are equal to those of the beam model, while the higher level beam model receives the gradient and Hessian of the complementary strain energy with respect to the resultants. The complementary strain energy gradient and Hessian are computed by defining suitable first and second order adjoint problems
Mother-child attachment and adoption. A study of adopted children compared with children growing up in the family
No full textThe aim is to study the attachment bond between adopted children and children who grow up in families; hypothesising an insecure attachment in the adopted child; verifying adoption as a protection factor and studying the quality of the attachment to biological and adoptive parents, according to the intergenerational transmission. 30 adopted children, age 4-10 years, adoption time (1-3years) and (above 3years) with the respective mothers are compared with a control group balanced and their mothers. Instruments: children: Human Figure Drawing (Machover 1953), Drawing the Family (Attili 2007), Separation Anxiety Test (Attili 2001), Child Behaviour Check List (Achenbach 1991); mothers: Parental Bonding Instrument (Parker et al.1979), Attachment Style Questionnaire (Fenney et al.1994) and SAT (Attili 2001). Adopted children are more likely to draw in the centre of the sheet and the family. Difficulties are encountered in aggressivity and attention in adopted children. The shorter the adoption time, the more likely it is to encounter problems concerning attention, egocentrism and physical contact. Self-height (HFD) correlates with adoption times. Both groups of mothers show a control pattern for affection; a good level of security, slight difficulty in unease-intimacy for the adoptive mothers. Greater correspondence between types of attachment biological mother-child vs adoptive mother-child
A Co-Simulation Algorithm for the Efficient Real-Time Parallel Solution of Multibody Systems
No full textNonlinear Dynamic of cable-stayed-beam by a parametric analytical model
No full textThe governing equations for dynamic transverse motion of a cable-stayed beam are obtained by means of a classical variational formulation. The analytical model permits a parametric investigation of lin- ear and non-linear behaviour in a family of cable-stayed beam systems. Analytical eigensolutions of the linearized equations are used to investigate how the mechanical characteristics in��uence the occur- rence of global, local and coupled modes. The exact eigenfunctions are assumed to describe the forced harmonic motion in the neighbourhood of a selected frequency. The frequency–amplitude relationship, obtained by the use of the multiple scale method, permits the description of softening and harden- ing behaviour in the global, local and coupled classes of motion. Copyright ? 2002 John Wiley & Sons, Ltd
Generalized Beam Models Analysis for Aeroelastic Morphing Applications
Full text linkGeneralized beam theory, Reduced–order modeling, Morphing wing structures Abstract. In the aerospace engineering field, morphing structures refer to mechanical structures capable of adapting their shape in order to improve some vehicle performance. Their analysis requires a computational model detailed enough to represent the internal structural parts which make morphing possible. These are often small with respect to the size of the external structure, so the computational cost of a full 3D finite element model would be high. We restrict our attention to straight, constant cross–section wings and rely on generalized beam theory to develop a computational model capable of analysing the morphing behaviour with a small number of degrees of freedom. We propose an extention of the generalized beam models presented by Morandini et al. (2010). From a singular value analysis of the cross–section finite element model, we derive an additional set of degrees of freedom strictly related to the morphing behaviour, and show the convergence of our projection–based reduced–order structural model to the full order one for some validation cases. The proposed method is applied to the analysis of the FishBAC morphing structure introduced by Woods et al. (2012
A parametric analytical model for nonlinear dynamics in cable-stayed beam
No full textThe governing equations for dynamic transverse motion of a cable-stayed beam are obtained by means of a classical variational formulation. The analytical model permits a parametric investigation of linear and non-linear behaviour in a family of cable-stayed beam systems. Analytical eigensolutions of the linearized equations are used to investigate how the mechanical characteristics influence the occurrence of global, local and coupled modes. The exact eigenfunctions are assumed to describe the forced harmonic motion in the neighbourhood of a selected frequency. The frequency-amplitude relationship, obtained by the use of the multiple scale method, permits the description of softening and hardening behaviour in the global, local and coupled classes of motion
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