Fluid structure interaction of a two-dimensional membrane in a flow with a pressure gradient with application to convertible car roofs

Original article can be found at : http://www.sciencedirect.com/ Copyright ElsevierThe flow-induced deformation of a membrane in a flow with a pressure gradient is studied. The investigation focuses on the deformation of aerodynamically loaded convertible car roofs. A computational methodology is developed with a line-element structural model that incorporates initial slackness of the flexible roof material. The computed flow–structure interaction yields stable solutions, the flexible roof settling into static equilibrium. The interaction converges to a static deformation within 1% difference in the displacement variable after three iterations between fluid and structural codes. Reasonably accurate predictions, to within 7%, are possible using only a single iteration between the fluid and the structural codes for the model problem studied herein. However, the deformation results are shown to be highly dependent on the physical parameters that are used in the calculation. Accurate representation of initial geometry, material properties and slackness should be found before the predictive benefits of the fluid–structure computations are sought. The iterative methodology overcomplicates the computation of deformation for the relatively small displacements encountered for the model problem studied herein. Such an approach would be better suited to applications with large amplitude displacements such as those encountered in sail design or deployment of a parachute.Peer reviewedFinal Accepted Versio

Raspberry Pi driven digital signage

Loughborough University makes extensive use of digital signage to display rapidly changing information to its staff, students and visitors. Within the library, digital signage displays show PC availability, study and meeting room bookings, IT support information and details of forthcoming events. To drive the displays small, inexpensive and low powered Raspberry Pi computers are used. The low cost and ease of use of the Raspberry Pi based solution has allowed the Library to have far more displays in use than would otherwise be possible, which provides for an enhanced user experience in the building. This paper describes how Raspberry Pi's can be used to drive displays, shows some of the cost savings that can be made and looks at some potential future applications of cheap, digital signage

Evaluating possible uses of a Raspberry Pi in an academic library environment

Loughborough University's Library Systems Team investigated two potential uses for Raspberry Pis. The first use to be identified for investigation was using the Raspberry Pi as a replacement for the existing OPAC hardware. While it met a majority of the requirements there were issues with the responsiveness to user input at certain times. The second use for Raspberry Pis investigated was to provide a number of digital signs to display details about resource bookings and the availability of PCs in IT labs around campus. The Raspberry Pi demonstrated that it was ideally suited to this task

Nonlinear Waves in Solid Continua with Finite Deformation

This work considers initiation of nonlinear waves, their propagation, reflection, and their interactions in thermoelastic solids and thermoviscoelastic solids with and without memory. The conservation and balance laws constituting the mathematical models are derived for finite deformation and finite strain using second Piola-Kirchoff stress tensor and Green's strain tensor. The constitutive theories for thermoelastic solids express the second Piola-Kirchoff stress tensor as a linear function of the Green's strain tensor. In the case of thermoviscoelastic solids without memory, the constitutive theory for deviatoric second Piola-Kirchoff stress tensor consists of a first order rate theory in which the deviatoric second Piola-Kirchoff stress tensor is a linear function of the Green's strain tensor and its material derivative. For thermoviscoelastic solids with memory, the constitutive theory for deviatoric second Piola-Kirchoff stress tensor consists of a first order rate theory in which the material derivative of the deviatoric second Piola-Kirchoff stress is expressed as a linear function of the deviatoric second Piola-Kirchoff stress, Green's strain tensor, and its material derivative. For thermoviscoelastic solids with memory, the constitutive theory for deviatoric second Piola-Kirchoff stress tensor consists of a first order rate theory in which the material derivative of the deviatoric second Piola-Kirchoff stress is expressed as a linear function of the deviatoric second Piola-Kirchoff stress, Green's strain tensor, and its material derivative. Fourier heat conduction law with constant conductivity is used as the constitutive theory for heat vector. The mathematical models are derived using conservation and balance laws. Alternate forms of the mathematical models are presented and their usefulness is illustrated in the numerical studies of the model problems with different boundary conditions. Nondimensionalized mathematical models are used in the computations of the numerical solutions of the model problems. All numerical studies are performed using space-time variationally consistent finite element formulations derived using space-time residual functionals in which the second variation of the residuals is neglected in the second variation of the residual functional and the non-linear equations resulting from the first variation of the residual functional are solved using Newton's Linear Method (Newton-Raphson method) with line search. Space-time local approximations are considered in higher order scalar product spaces that permit desired order of global differentiability in space and time. Extensive numerical studies are presented for different boundary conditions. Computed results for non-linear wave propagation, reflection, and interaction are compared with linear wave propagation to demonstrate significant differences between the two, the importance of the nonlinear wave propagation over linear wave propagation as well as to illustrate the meritorious features of the mathematical models and the space-time variationally consistent space-time finite element process with time marching in obtaining the numerical solutions of the evolutions