Free vibration characteristics of multi-core sandwich composite beams: Experimental and numerical investigation

This study investigates the free vibration responses of laminated composite sandwich beam with multi-cores using experimental and numerical methods. The laminated composite face sheets are made by using hand layup method. An experimental modal test has been carried for different configurations of multi-core sandwich beams under different end conditions. The single-core and multi-core sandwich beams has been modeled and the natural frequencies of sandwich beams are determined using ANSYS software. The numerical model is verified by comparing the obtained natural frequencies with experimental results. The numerical and experimental results indicate that the multi-core sandwich beam greatly influences the structural stiffness compared with single-core sandwich beam under different end conditions. Furthermore, the influence of several parameters such as the end conditions, thickness of the core layer, and stacking sequence on the natural frequencies of the various configurations of the multi-core sandwich beams are presented.

Free Vibration and Instability Analysis of Sandwich Plates with Carbon Nanotubes-Reinforced Composite Faces and Honeycomb Core

In this study, the instability regions of a honeycomb sandwich plate are investigated for different end conditions under periodic in-plane loading. The core layer of the sandwich plate is made of carbon nanotube (CNT)/glass fiber-reinforced honeycomb and the face layers of CNT/glass fiber- reinforced laminated composite. The governing equations are derived using classical laminated plate theory (CLPT) and solved numerically by using finite element formulation. The effectiveness of the developed finite element formulation is demonstrated by comparing the results in terms of natural frequencies with those available in the literature. The effects of CNT wt.% on the core material, CNT wt.% on the skin material, ply orientation and various end conditions on the variation of natural frequencies, loss factors and instability regions are studied. Finally, some inferences for the effects of CNT reinforcement on the honeycomb sandwich plate subjected to the periodic in-plane loads are discussed.

The Digital Carpenter: An Exploration In Manufacturing Complex Timber Structures Through Digital Design Techniques

<p><b>Using digital design and fabrication methods, can a bespoke visual timber spaceframe be feasibly constructed to allow greater choice in architectural freedom?</b></p> <p>At present, three-dimensional timber spaceframes are often not feasible as an architectural solution, as the end conditions are quite complex. The result of these complex situations is that they are not time or cost-effective when constructed by hand.</p> <p>Subsequently, architects and designers tend not to frequently use these trusses as an expressive structural member over steel and concrete alternatives.</p> <p>The fourth industrial revolution is making massive technological advancements in bringing together the digital realm and the physical. </p> <p>Architecture and the building industry as a whole are making steps towards harnessing some of these new technologies. However, there is far more that can be explored with what is already available. </p> <p>Robotic fabrication brings with it the ability to automate specific tasks with an incredibly high tolerance of precision, allowing for the potential methods of construction, craft, and customisation that have previously been difficult, slow, and ultimately not cost-effective enough to pursue.</p> <p>This thesis sets out on the premise that designing through DFMA (Design For Manufacturing and Assembly), the precision of robotic fabrication could be used to make these complex end conditions and assembly of these timber structures much faster, and therefore more feasible as an architectural solution.</p>

The Digital Carpenter: An Exploration In Manufacturing Complex Timber Structures Through Digital Design Techniques

<p><b>Using digital design and fabrication methods, can a bespoke visual timber spaceframe be feasibly constructed to allow greater choice in architectural freedom?</b></p> <p>At present, three-dimensional timber spaceframes are often not feasible as an architectural solution, as the end conditions are quite complex. The result of these complex situations is that they are not time or cost-effective when constructed by hand.</p> <p>Subsequently, architects and designers tend not to frequently use these trusses as an expressive structural member over steel and concrete alternatives.</p> <p>The fourth industrial revolution is making massive technological advancements in bringing together the digital realm and the physical. </p> <p>Architecture and the building industry as a whole are making steps towards harnessing some of these new technologies. However, there is far more that can be explored with what is already available. </p> <p>Robotic fabrication brings with it the ability to automate specific tasks with an incredibly high tolerance of precision, allowing for the potential methods of construction, craft, and customisation that have previously been difficult, slow, and ultimately not cost-effective enough to pursue.</p> <p>This thesis sets out on the premise that designing through DFMA (Design For Manufacturing and Assembly), the precision of robotic fabrication could be used to make these complex end conditions and assembly of these timber structures much faster, and therefore more feasible as an architectural solution.</p>

Numerical Study on Buckling Resistance of Uniaxially Compressed Laminates Containing V-Shaped Edge Notch

The purpose of this study is to investigate the impact of a V-shaped cutout on the buckling strength of E-glass epoxy composite laminates. In aircraft components, cutouts are more often used for inspection, ventilation, access to critical areas, fitting a particular component, and increasing the strength to weight ratio of the structure. In this paper, symmetric and antisymmetric laminates of E-Glass/Epoxy unidirectional are used and the effect of notch parameters such as notch radius(r), depth of the notch(h), and notch angle(α) is observed under monoaxial compression. Effects of end conditions and plate aspect ratio(l/b) are analyzed. It is observed that the notch radius does not have a considerable effect on buckling strength but the notch angle after 90⁰ shows a good dip in buckling loads as compared to 30⁰,45⁰, and 60⁰. Depth of notch and end conditions creates a considerable loss in buckling strength. As the h/b ratio is increased, the drop in buckling strength becomes significant. Clamped -pinned end condition of the plate gives a lower value of load multiplier as compared to clamped -clamped. As we increase the l/b ratio of the plate, buckling of the plate becomes easier. The position of the notch (a) also affects buckling strength which is maximum for a/l=0.25 and minimum for a/l=0.5.

Development of Polynomial Mode Shape Functions for Continuous Shafts with Different End Conditions

Common methods used to determine the solutions for vibration response of continuous systems are assumed mode method, Rayleigh-Ritz method, Galerkin Method, finite element method, etc. Each of these methods requires the shape functions which satisfy the boundary conditions. Shape functions derived in most of the classical textbooks are simple trigonometric functions for some end conditions but are very complex transcendental functions for many end conditions. It is very difficult to determine the vibration response of a continuous system analytically by using such transcendental shape functions. Hence this paper presents a method to develop polynomial shape functions required to solve the vibration of continuous shafts with different end conditions. The natural frequencies obtained from the developed polynomial shape functions are compared to those obtained from the classical transcendental shape functions and found very close for the first three modes.