The Influence of the Testing Machine on the Buckling of Cylindrical Shells Under Axial Compression

Testing machine influence on buckling of cylindrical shells under axial compressio

The effect of end slope on the buckling stress of cylindrical shells

End slope effect on buckling stress of seamless cylindrical shell

Experimental investigation of the effect of general imperfections on the buckling of cylindrical shells

Imperfection survey data on cylindrical shells before and during axial compression loading up to buckling loa

Observation of Damage Growth in Compressively Loaded Laminates

An experimental program to determine tie phenomenological aspects of composite-panel failure under simultaneous compressive n-plane loading and low-velocity transverse impact [C-75 m/s (0-250 ft/s)] is described. High-speed photography coupled with the shadow-moiré technique is used to record the phenomenon of failure propagation. The information gained from these records, supplemented by plate sectioning and observation for interior damage, has provided information regarding the failure-propagation mechanism. The results show that the failure process can be divided roughly into two phases. In the first phase the plane is impacted, and the resulting response causes interlaminar separation. In the second phase the local damage spreads to the undamaged portion of the plate through a combination of laminae buckling and further delamination

Effect of stress concentrations in composite structures

Composite structures have found wide use in many engineering fields and a sound understanding of their response under load is important to their utilization. An experimental program is being carried out to gain a fundamental understanding of the failure mechanics of multilayered composite structures at GALCIT. As a part of this continuing study, the performance of laminated composite plates in the presence of a stress gradient and the failure of composite structures at points of thickness discontinuity is assessed. In particular, the questions of initiation of failure and its subsequent growth to complete failure of the structure are addressed

Dynamic Considerations for Control of Closed Life Support Systems

Reliability of closed life support systems depend on their ability to continue supplying the crew's needs during perturbations and equipment failures. The dynamic considerations interact with the basic static design through the sizing of storages, the specification of excess capacities in processors, and the choice of system initial state. A very simple system flow model was used to examine the possibilities for system failures even when there is sufficient storage to buffer the immediate effects of the perturbation. Two control schemes are shown which have different dynamic consequences in response to component failures

Postbuckling delamination of a stiffened composite panel using finite element methods

A combined numerical and experimental study is carried out for the postbuckling behavior of a stiffened composite panel. The panel is rectangular and is subjected to static in-plane compression on two opposite edges to the collapse level. Nonlinear (large deflection) plate theory is employed, together with an experimentally based failure criterion. It is found that the stiffened composite panel can exhibit significant postbuckling strength

A Mechanical Model for Elastic Fiber Microbuckling

A two-dimensional mechanical model is presented to predict the compressive strength of unidirectional fiber composites using technical beam theory and classical elasticity. First, a single fiber resting on a matrix half-plane is considered. Next, a more elaborate analysis of a uniformly laminated, unidirectional fiber composite half-plane is presented. The model configuration incorporates a free edge which introduces a buckling mode that originates at the free edge and decays into the interior of the half-plane. It is demonstrated that for composites of low volume fraction (<0.3), this decay mode furnishes values of buckling strain that are below the values predicted by the Rosen (1965) model. At a higher volume fraction the buckling mode corresponds to a half wavelength that is in violation of the usual assumptions of beam theory. Causes for deviations of the model prediction from existing experimental results are discussed