1,721,953 research outputs found
Cummings, Levi F.
No full textCarte de Visite of 1st Lieutenant Levi F. Cummings, 30th Maine Infantry Company C, and 25th Maine Infantry, Company H; From the MacDonald Collectionhttps://digitalmaine.com/arc_civilwarportraits/2062/thumbnail.jp
Cummings, Levi F.
No full textCarte de Visite of 1st Lieutenant Levi F. Cummings, 30th Maine Infantry Company C, and 25th Maine Infantry, Company H; From the MacDonald Collectionhttps://digitalmaine.com/arc_civilwarportraits/2062/thumbnail.jp
Concrete in Italy. A review of a century of concrete progress in Italy,Part I: Technique and architecture
No full textConcrete in Italy. A review of a century of concrete progress in Italy Italy,Part II: Contribution to a modern theory of structural concrete and to international codification
No full textConservative systems showing instability in tension
Full text linkWithin the framework of a second-order theory, the stability of a straight beam, hinged at one end and supported at an intermediate point, is studied. Two different tensile loading conditions are applied to the beam, causing bifurcation and instability. A new analogy is shown between one of these stability problems and the elastic circular arch problem on spring soil with negative stiffness. The relationship between the results presented here and those presented in Gajewski and Palej (1974), in Zaccaria et al. (2011), and in Feriani and Carini (2017) is shown
On the stability of elastic structures subjected to follower forces
Full text linkWithin the framework of a second-order theory, this study revisits classical stability problems characterized by critical loads associated with dynamic instability, previously explored by Feriani and Carini (in: Zingoni (ed) Insights and innovations in structural engineering, mechanics and computation, 2016) . The primary focus remains on systems exclusively comprising a single lumped mass. This simplification, together with the assumption of a negligible axial strain and the adoption of a second-order theory, reduces the analysed systems to problems featuring a single Lagrangian coordinate. Consequently, static methods become applicable, facilitating the derivation of analytical expressions for stiffness coefficients and enabling an investigation into dynamic stability. The study begins by examining a well-established case: a cantilever beam with a lumped mass positioned at its free end, subjected to a follower load, as presented in Panovko and Gubanova (Stability and oscillations of elastic systems: models, paradoxes and errors, Nunka Press, Moscow, 1967). In this current work, a novel lumped mass system is explored. The system consists of a straight-axis beam characterized by a constant cross-section area and stiffness. The distributed mass of the beam is neglected and the beam is hinged at one end, simply supported at an intermediate point, and left free at the other end, where a lumped mass is introduced. Various loading scenarios are scrutinized, including: (a) The application of a follower force to the free end; (b) The imposition of two forces-one conservative and one follower-both applied to the free end; and (c) The application of a uniformly distributed follower force along the length of the beam. As seen in the examples introduced in Feriani and Carini (2016), the new examples considered in the present paper reveal that the first asymptote of the stiffness coefficient corresponds to the critical load. This critical load corresponds to the phenomenon known as divergence at infinity, as described by Felippa (Nonlinear finite element methods, 2014). It is also confirmed that, in all cases, the first dynamical critical load equals the minimum value between the static buckling load of the original structure and the static buckling load of an auxiliary structure. This last differs from the original one because the concentrated mass is replaced by a constraint fixing the corresponding Lagrangian coordinate
A saddle point formulation for linear viscoelastic analysis by Boundary Integral Equations
No full text
- …
