Case Studies
A
Strategy for Teaching Finite Element Analysis to Undergraduate Students (414k)
"The analytical power and design flexibility offered by
the Finite Element Method (FEM) can be all too readily masked from the first time user by
its apparent complexity. The steep learning curve can appear daunting when the method is
first encountered, and FEM needs to be sensitively introduced, with carefully graded
examples if students are not to be put off the subject completely. In this paper the
author describes a strategy which he believes enables students to experience for
themselves how beneficial FEM can be, whilst at the same time, warns them of the pitfalls
and potential dangers".
Finite
Element Analysis of Structural Steelwork Beam to Column Bolted Connections (423k)
"A combination of simple fabrication techniques and speedy
site erection have made bolted endplates one of the most popular methods of connecting
members in structural steelwork frames. Although simple in their use, bolted endplates are
extremely complex in their analysis and behaviour. This paper reports on a Steel
Construction Institute funded PhD research program which uses a combination of full scale
testing and materially non-linear three dimensional finite element analyses (FEA) in order
to investigate extended end plate beam-to-column connections".
See also the LUSAS Civil
& Structural case study Beam
/ Column Moment Connection Research
Finite
Element Analysis of Impact Damaged Honeycomb Sandwich Panels (515k)
"Due to high stiffness and strength to weight ratios,
composite sandwich is used increasingly in aerospace applications. The main drawback of
sandwich structure is its low resistance to impact damage and the extent to which the
strength of the structure is reduced under compressive loading. In this study, it is
proposed that a continuum damage model is used to model crushing due to impact. The model
describes the compressive behaviour of honeycombs made from materials that are prone to
elastic buckling. The material behaviour in compression is described by a combination of
three constitutive models namely elastic, continuum damage and inelastic strain
accumulation. The model has been interfaced with LUSAS and is used to model
“soft” impacts onto minimum gauge Nomex™ sandwich. The materials and
dimensions are typical of sandwich panels found in commercial aircraft. Results from the
LUSAS analysis are compared to experimental data and are found to compare well. The aim of
this on-going project is to provide a means of evaluating impact damage for various
honeycomb sandwiches".
Links to external case
studies
Compliant
Blades for Wind Turbines
This paper details an aeroelastic study
of compliant blades used in the passive power control of
horizontal-axis wind turbines. By designing the blades using fibre-reinforced
composite materials, coupling between bending and torsion can be
incorporated. The present work investigates the capability of a 50 kW
constant speed wind turbine to automatically shed power in gusts by
feathering the blades, i.e. twisting them towards the relative wind
vector thus reducing the angle of attack, whilst bending away from the
wind.
The
Stability of Plywood Webs of Box-girder Beams
Critical loads and other buckling
information for plywood webs are presented. The results were produced
by LUSAS analyses in which the plywood was modelled as a layered
composite material with each layer being given appropriate linear
elastic orthotropic properties. Stability analyses were performed by
allocating a small initial curvature to the web panels and applying
incremental loads giving geometric non-linearities. Results are
presented for various combinations in plane bending and in plane
shear. For situations were bending actions predominate it is suggested
that the face grain of the plywood should be horizontal but for
locations were shear actions are significant there may be advantages
in ensuring that the face grain is vertical. The results suggest that
current design rules are not conservative.
Integrity
Assessment of Large Dams NW-IALAD
A study
using the finite element program LUSAS (LUSAS, 2002) to analyse the
response of a concrete gravity dam subjected to the hydrostatic loads
and uplift pressures. The CIGB/ICOLD (1999) benchmark dam is chosen
for this analysis. Linsbauer and Bhattacharjee (1999) have also
adopted the same concrete dam in their studies on the effect of uplift
pressure on dam safety...
Finite
Element Modelling of Moisture Absorption in Single Fibre Reinforced
Composite Systems
LUSAS has been used to model the effects of moisture absorption in single fibre reinforced epoxy-matrix composite systems. The composite geometries are based on the previous experimental investigation by Bannister and consist of a single fibre embedded in a diffusion slab (DS), and a single fibre protruding from opposite ends of a slab (DFPO). The FE work produced axial fibre strain profiles consistent with both previous and current experimental work. The DS composite produced a conventional shear lag profile, and the DFPO composite produced a more complicated profile with pronounced maxima near the fibre ends.
The
Influence of Construction Technology on the Mechanics of Masonry Railway
Bridges
Technological details of masonry arch bridges are of great importance to the mechanical response of the structure. Internal spandrels, hollowing in piers and abutments, backfill type and material, vault thickness and its effective shape contribute to modify the structural performance of these bridges. When a mechanical model for a masonry bridge is formulated, specifically if it is a FEM model, not all of the technological details can and need to be represented, but some should not be neglected in order to retain some important features of the structural
response. In this paper, an example of an in-service 18-span railway viaduct is studied by means of FEM models in order to take into account the role of those details and to give an estimate of their structural effect. In particular, it is shown how the misjudgement of the presence of some bridge element and of their structural contribution can lead to over- or underestimate the natural frequencies of the bridge, leading to significant errors in identification procedures.
 Commercial Case Studies
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