Heat and Moisture Modelling of Vacuum Insulated Retrofits with Experimental Validation

Vacuum insulation panels (VIPs) offer 8-10 times the thermal resistance of fiberglass insulation and would fit the need for a low conductivity exterior insulation. A composite insulation panel using VIPs encased in rigid foam was developed, built, and tested. Two different sizes of VIPs were used for that stage of the project, and after monitoring and evaluation, they showed contrasting results. A simulation study was performed to find the optimal VIP solution that maximized the effective thermal conductivity and minimized the mould growth potential. In total, 5 wall assemblies with VIPs used as the exterior insulation were simulated using WUFI and WUFI2D. The simulations showed that the humidity levels at the inside face of the OSB inboard of the VIPs decreased when 200 mm by 300 mm VIPs were used, but they did not reach the thermal performance thresholds of R5.28 m2K/W. The hygrothermal analysis showed that under similar conditions, a VIP insulated wall assembly would have a lower relative humidity at the sheathing surface compared to EPS and XPS. The one-and two-dimensional simulations were compared and found that WUFI Pro was capable to evaluate a VIP-insulated wall assembly.

Annular Post-Compression by FRP inside Mortar Joints and Vertical Post-Compression by Stainless Steel, for Seismic and Wind Retrofitting of Historical Masonry Chimney

This paper shows the efficiency of the vertical and annular post-compression for wind and seismic structural behavior improvement of slender masonry chimney. For this aim a case study approach regarding an old masonry chimney is used. The paper shows the safety analysis and the safety improvement obtained applying at the same time a vertical and an annular masonry post-compression. The vertical post-compression is obtained through the post-tensioning of twenty-four vertical stainless-steel thin bars. These bars are connected to the chimney masonry only at the basement and at the top. They are placed inside the central void and horizontally distributed along a circumference near the inside face of the masonry, but without to touch it. The annular post-compression is obtained post-tensioning forty-five annular aramidica “not twisted” cables, placed and glued (after the post-tensioning) inside horizontal mortar joints of the more external masonry brick layer.

La aplicación del arco de herradura en el Panteón (Roma) y su proyección simbólica en la estela de Valens (León, NW Hispania)

Horseshoe arches samples in funerary steles from north-western Hispania are usually identified as simple geometric decorative motifs. This opinion has also been associated with what is represented in the stele of Valens (León, NW Spain), despite the fact that the artistic quality of the bas-relief allows to link it better with an architectural element. Likewise, it is very remarkable the practical absence of references in specialized historiography to another significant sample of horseshoe arch, despite being part of one of the most important classical monuments: the Pantheon of Rome. Located on the inside face of the door, the prominence of this majestic arch in the construction design of the Pantheon explains the symbolic meaning of what is represented in the stele of Valens.

Numerical analysis of the effect of the change in the ride height on the aerodynamic front wing–wheel interactions of a racing car

An investigation into the influence of the ground clearance on the aerodynamic interactions between the inverted front wing and the wheel of a racing car was conducted using computational fluid dynamics. Height-to-chord ratios h/ c from 0.075 to 0.27 were assessed for a single-element wing with a fixed angle of 4° and for two wing spans, one of which completely overlapped the wheel and the other which had its endplate coincident with the inside face of the wheel. With a narrower span, a lower peak downforce was achieved at a higher ground clearance owing to changes in the lower endplate vortex strength whereas, with a wider span, no downforce loss was observed, with decreasing clearance for those tested. This contrasted distinctly with the performance of the wing in isolation. The wheel lift was scarcely affected with decreasing wing ground clearance for the narrower span but decreased significantly for the wide-span wing at low ground clearances. The vortex paths changed considerably with the ground clearance, with a strong coupling to the wing span; a state in which the main vortex was destroyed in the contact patch of the wheel was identified.

Mechanical and Thermal Simulation of a Multi-Functional Hybrid Composite

Hybrid composites are increasingly concerned by the investigators and widely used in many areas, especially aerospace industry, for its multi-functional properties. In the present study, the mechanical properties and thermal properties of a structural component manufactured by a new hybrid composite consisting of quartz fiber, carbon fiber and cyanate ester resin has been investigated by finite element numerical simulation. The results show that the mechanical properties of the structural component are very good. And the temperature of inside face is 43.8 °C. The thermal strain is lower than 0.15%.

Optimal Analysis and Application in the Design of Ultra-Light Truss-Core Structures

A novel method for characterizing a high actuating capability light-weight actuator is described and analyzed. The actuator comprises a truss core and smart face-sheets which result in bending. The deformation of this beam actuator is obtained by changing voltage inside face-sheets made from smart material. Materials selections are discussed for practice, and then optimization is designed to ascertain minimum weight or maximum achievable displacement subject to two types of constrains. Results show the composite trusses have higher stiffness and strength than metal trusses. Comparisons with two corrugated core actuators, the truss-core design has better actuating capability at specified weight.

Application of Adomian’s Decomposition Procedure to the Analysis of Convective-Radiative Fins

This paper presents a method which may be used to determine the temperature distribution within a convective-radiative longitudinal fin of variable thermal conductivity, subject to convection heat transfer from a fluid of known temperature Tf through the inside face of the primary surface, and which experiences convection-radiation heat dissipation into the environment at its tip. The paper demonstrates the use of the Adomian decomposition method in generating an analytical solution of the resulting nonlinear energy balance equation with nonlinear boundary conditions.

Rotordynamics Involving Axial Rubbing Against a Disk

Test results are presented involving axial rubbing of a test rotor with an overhung disk to investigate test results cited by Den Hartog [1]. Point rubbing was introduced via a rod on the inside (motor-drive side) and outside faces of the overhung disk for multiple operating conditions (running speeds below and above the critical speed) and multiple shaft configurations. For supercritical running speeds, no change in the response spectrum was observed. For subcritical running speeds, a slight increase of response at twice running speed was observed. “Face” axial rubbing was introduced by forcing a contact between the outside face of the disk and a flat surface. Rubbing at running speeds below the critical speed produced: (i) a small backwards component at the running speed frequency, (ii) a large backward-whirl component at twice running speed, and (iii) a very large, twice-running-speed, forward-whirl component. Rubbing at running speeds well above the critical speed produced a subsynchronous forward component near the critical speed. The large twice-running-speed results due to rubbing at the outside face were comparable to Den Hartog’s. However, point rubbing on the inside face did not produce the subsynchronous backward-whirl response cited by Den Hartog. Analysis of a nonslipping kinematic whirl condition (comparable to classical dry friction whipping) for the face of an overhung disk against a stationary surface predicts reverse asynchronous whirl; however, testing over a wide range of parameters failed to produce this response. None of the present test results produced the types of very high vibration levels and grave consequences that have been produced in test rigs for conventional, radial dry-friction whirl and whip.