Search results for "buckling"

Crumpling of a stiff tethered membrane.

2003

first-principles numerical simulation model for crumpling of a stiff tethered membrane is introduced. In our model membranes, wrinkles, ridge formation, ridge collapse, as well as the initiation of stiffness divergence, are observed. The ratio of the amplitude and wave length of the wrinkles, and the scaling exponent of the stiffness divergence, are consistent with both theory and experiment. We observe that close to the stiffness divergence there appears a crossover beyond which the elastic behavior of a tethered membrane becomes similar to that of dry granular media. This suggests that ridge formation in membranes and force-chain network formation in granular packings are different manife…

Stability of Axially Moving Plates

2019

This chapter focuses on the stability analysis of axially moving materials, in the context of two-dimensional models. There are many similarities with the classical stability analysis of structures, such as the buckling analysis of plates. However, the presence of axial motion introduces inertial effects to the model. We consider the stability of an axially moving elastic isotropic plate travelling at a constant velocity between two supports and experiencing small transverse vibrations. We investigate the stability of the plate using an analytical approach. We also look at elastic orthotropic plates, and an elastic isotropic plate subjected to an axial tension distribution that varies in th…

Analytical and Numerical Methods for the Evaluation of Critical Conditions in Longitudinal Bars of RC Columns

2017

Buckling collapse of reinforcing bars in concrete members is usually observed in framed structures after severe earthquakes. Second order effects modify the compressive response of steel bars, reducing ductility and affecting the post-elastic branch. Literature investigations show that instability can involve more stirrups, or it can be limited to the pitch. If the critical length is not carefully estimated, transverse steel’s failure can be achieved in brittle manner, causing the sudden loss of confinement in the inner concrete. This paper presents the results of a theoretical investigation, aiming to evaluate the reliability of different approaches for calculating critical conditions of l…

A Rayleigh-Ritz approach for postbuckling analysis of variable angle tow composite stiffened panels

2018

Abstract A Rayleigh-Ritz solution approach for generally restrained multilayered variable angle tow stiffened plates in postbuckling regime is presented. The plate model is based on the first order shear deformation theory and accounts for geometrical nonlinearity through the von Karman’s assumptions. Stiffened plates are modelled as assembly of plate-like elements and penalty techniques are used to join the elements in the assembled structure and to apply the kinematical boundary conditions. General symmetric and unsymmetric stacking sequences are considered and Legendre orthogonal polynomials are employed to build the trial functions. A computer code was developed to implement the propose…

Post-buckling analysis of cracked multilayered composite plates by pb-2 Rayleigh–Ritz method

2015

Abstract A pb-2 Rayleigh–Ritz variational approach for the analysis of post-buckling behavior of cracked composite plates is presented. The plate is modeled by the first order shear deformation theory taking geometric nonlinearities into account through the von Karman’s theory. General stacking sequences are considered. Cracks are modeled by using subdomain decomposition of the plate coupled with penalty techniques, used to augment the variational statement with the needed continuity conditions along the connected subdomains edges. Numerical procedures have been developed and used to validate the present solution by comparison with available literature results. Original results are then pre…

Post-Buckling Analysis of Damaged Multilayered Composite Stiffened Plates by Rayleigh-Ritz Method

2016

A Rayleigh-Ritz approach for the analysis of buckling and post-buckling behavior of cracked composite stiffened plates is presented. The structure is modeled as the assembly of plate elements modeled by the first order shear deformation theory and taking geometric nonlinearities into account through the von Karman’s theory assumptions. Continuity along the plate elements connected edges and the enforcement of rigid and elastic restraints of the plate boundaries are obtained by using penalty techniques, which also allow to straightforwardly implement efficient crack modeling strategies. General symmetric and unsymmetric stacking sequences are considered and numerical procedures have been dev…

Square Ring Compression: Numerical Simulation and Experimental Tests

1996

In the upsetting process of square rings buckling problems often arise, depending on the geometry of the ring and on the frictional conditions at the punch-workpiece interface, yielding to the practical unacceptability of the forged component. Consequently in order to make up a set of rules to be introduced in an expert system able to assist the designer of cold forming sequences, a knowledge base has been built up, by means of a set of numerical simulations, the results of which have been validated by several experimental tests.

A single-domain Ritz approach for buckling and post-buckling analysis of cracked plates

2019

Abstract A Ritz approach for the analysis of buckling and post-buckling of plates with through-the-thickness cracks is presented. The plate behavior is described by the first order shear deformation theory and von Karman’s geometric nonlinearity. The admissible functions used in the displacements approximation are series of regular orthogonal polynomial supplemented with special functions able to decribe the dicontinuity across the crack and the singularity at the crack tips; boundary functions are used to fullfill the homogeneous essential boundary conditions. Convergence studies and analysis results are presented for buckling and post-buckling of plates with a central through-the-thicknes…

Architecture and kinematics of forearc basins and intra-caldera resurgences: new insight from the Paola Basin (western offshore Calabria region) and …

This thesis deals with the patterns of tectonic deformation at different time and spatial scales ranging from tens to millions of years and from one to tens of kilometers, respectively. The study areas are the Campi Flegrei (Campania region, Italy) and Paola Basin (western offshore Calabria region, Italy). The Campi Flegrei and its offshore prolongation, the Pozzuoli Bay, are a laboratory for investigating volcano-tectonic deformations at 1yr-1kyr timescale and 1km spatial scale related to the dynamics of the Neapolitan Yellow Tuff (NYT) caldera and its intra-caldera resurgence. Resurgence is the late stage, long-term uplift of a collapse caldera floor to form a dome-like structure. The com…

Multicriterion design of frames with constraints on buckling

2011

The present paper is devoted to the optimal design of frame structures subjected to static and dynamic loading assuming the material behaviour as elastic perfectly plastic. The relevant optimal design problem is formulated as a minimum volume search problem. The minimum volume structure is determined under suitable constraints on the design variables as well as accounting for different resistance limits: the elastic shakedown limit and the instantaneous collapse limit, considering for each limit condition suitably chosen amplified load combinations. The effects of the dynamic actions are studied on the grounds of the dynamic features of the structure taking into account the structural perio…