Field measurement and simulation of the dynamic response of a railway viaduct

• Mehrdad Bisadi, a PhD researcher at the University of Auckland, is using LUSAS to investigate the accuracy and reliability of the impact factors used to design and assess New Zealand rail bridges. The objective has been to fine-tune a LUSAS Bridge model prior to carrying out numerical modelling of the dynamic response of the viaduct for different train dynamic characteristics. A weigh-in-motion system measured the train characteristics during field monitoring. The measured data was then used to define the train configurations in the LUSAS software. Interactive Modal Dynamics analysis with LUSAS computed the dynamic response of the viaduct during train crossings. A comparison between the measured and simulated results showed that the LUSAS model accurately predicts observed displacements.

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.

LUSAS Academic

Case Studies