Papers by Keyword: R-Value

Abstract: In recent years, the whole world has been ailed by the change in climate with global warming and its negative effects on Earth’s climate system. Increased emissions and amplified energy consumption have resulted in a remarkable rise across the various climatic regions of Egypt, intensifying the thermal stresses on building facades. So to address this matter through a quantitative study, how climate change influences energy consumption rates will be analysed by referring back to the ECEEE records and Egypt's weather data files. The weather data files follow the seven climate regions and the different cities, starting with Alexandria, then Cairo, Minya, Asyut, Hurghada, Kharga, and finally Aswan. Based on the ECEEE records, each climate region has a particular thermal resistance (R-value) regulated by its zone location and weather conditions, thereby regulating consumption and reducing energy consumption. The simulations will also compare the most recent weather data files for 2021 with the original from 2006 in order to determine whether they are still applicable to today's energy depletion rates. The DesignBuilder program will be used to examine and compare R-values for an air-conditioned office space (6x4) m with a southwest orientation between 2006 and 2021. The results show an increase in Delta and Cairo Regions (2) by 50% , South Upper Egypt Regions (4) by 57% , and East Coast Regions (5) by 43% that were treated with XPS Extruded Polystyrene - CO2 Blowing as an insulation material addition, with its thickness adjusted according to the different regions. Keywords Climate Change, Energy Consumption, R-Value, Energy Code, Climatic Regions, Office Space, Orientation, Software Simulation, Envelope

Abstract: Aluminium 8011 cast plates subjected to cold rolling to reduce thickness from 12 mm to 3.5 sheets. As rolled aluminium sheet was subjected to annealing treatment after rolling. This work deals with the study of planar and normal anisotropy parameters of as rolled aluminium and rolled with annealed aluminium sheets. The tensile test samples were cut at 0°, 30°, 45°, 60° and 90° with respect to the rolling direction of as rolled Al sheet and rolled with annealed Al sheet. Tensile properties were measured at different orientations to the rolling directions. The wide variation in tensile strength was found in case of as rolled Al samples at different orientation to rolling direction of sheet (208 to 243 MPa). On the other hand nearly uniform tensile strength (128 MPa to 132 MPa) was measured for rolled and annealed Al samples at different orientations. As rolled Al samples shows anisotropic tensile properties where as isotropic tensile properties were measured for rolled with annealed Al samples. Al grains are more elongated along the rolling directions where as rolled and annealed Al sample shows more equiaxed grains which is attributed to isotropic behaviour of Al sheets. The normal anisotropy parameter or average r_m value is higher (1.24) in case of rolled and annealed sheet sample as compared to as rolled Al sheet r_m value (1.06). This is attributed to isotropic behaviour of rolled and annealed samples. Toughness and ductility properties are improved more than 3 times in case of rolled and annealed Al sheet samples. Annealing treatment of rolled Al sheet samples shows elongated grain morphology changes to equiaxed grains of aluminum which tends to improved formability and isotropic mechanical properties Al sheet. For determination of normal anisotropy (r_m) value, tensile results R values are required at angles of 0 degrees, 45 degrees, and 90 degrees. However in this study additional R values are estimated at 30 degree and 60 degree in order to understand trend of R value at every 30 degree from 0 to 90 degree.

Abstract: Sheet metal forming forms in numerous industries like vehicle depend on the yielding of the sheet metals when strained. Yielding is portrayed by plastic flow of the materials when strained. The yield point if there should be an occurrence of uniaxial tension can be effectively decided from the pressure strain diagram, yet if there should arise an occurrence of multi axial Stresses it gets complicated. A connection between the principal stresses is required determining the conditions under which plastic flow occurs. This intricacy is tended to by the anisotropic yield capacities. Likewise, the tests used to acquire yield loci might be costly and time taking in such case these yield capacities end up being exceptionally viable. The yield criteria additionally help in deciding planar distribution of yield stresses and anisotropic coefficients, which gives a decent gauge of these mechanical parameters without having to through the pain of trial assurance. This project aims at using Hill 1948 criterion to obtain the Yield surface Diagrams for SS304 in annealed and original state and subsequently obtain the planar distribution of the uniaxial yield stress and anisotropic coefficient. Also, the performance evaluation of both the distributions will be done using accuracy index.

Abstract: Footfall induced vibrations can occur in elevated walking surfaces in structures due to normal human activities such as walking and running. If the vibrations are too high, they can cause occupant discomfort. Being able to reliably estimate the dynamic properties of the supporting structural system is a key part of designing a structure to limit such vibrations. However, currently, methods to assess the floor vibration response in realistic structures is not well known. This paper describes walking tests at an office building in the Christchurch CBD designed for earthquake both before and after fitout to determine properties and response. Sensitivity of floors to vibration response parameters such as the individual’s weight, the walking frequency and the presence of non-structural elements is considered. The results are then compared to numerical analyses which were conducted using OASYS, a commercial footfall analysis package, and SeismoStruct, a frame analysis software package. It was found from experimental tests dimensionless response factors (R-values) were generally less than 5 even for pre fit-out indicating that the floor considered is likely to be comfortable for occupants. The effect of fit-out tended to decrease the R-value by a factor of 1.2, but there was considerable scatter. The numerical OASYS and SeismoStruct models had similar stiffness and damping. However, they tended to estimate R-values greater about 1.0 larger than that found from walking field tests, which could be due to the fact that a larger damping value of the actual floor were calculated. These were 7 % and 10 % for pre fit-out and post fit-out respectively. In addition, in the field walking tests, the frequency range of 1.8-2.2 Hz had a negligible effect on the response. There was generally positive correlation between walker mass and R-value.

Abstract: In the previous papers, the author discussed the role of r-value (anisotropic parameter in plasticity) on the surface roughening after plastic deformation. In the present paper, discussion is made on the effects of mutual constraint of deformation between neighboring grains at the grain boundary on the surface roughening. A characteristic parameter called constraint ratio is introduced to express the degree of the mutual restriction between grains. The well-known Coffin-Manson relation in low cycle fatigue is deduced considering to the surface roughening after cyclic deformation.

Abstract: During processing of age-hardenable AA 6xxx series alloys for automotive applications the sheets may experience significant time spans between solution heat treatment at the aluminium supplier and age hardening upon the final paint bake cycle at the carmaker. Natural ageing during these pause times is known to greatly affect materials properties of autobody sheet. In the present study we explore the impact of natural ageing on the tensile properties and the in-plane anisotropy of alloy AA 6005C. Materials properties at various degrees of natural ageing are modelled with the help of a nanoscale material model NaMo, which consists of a precipitation model simulating the formation of clusters and phases upon natural ageing as input to a mechanical model simulating the evolution of yield strength and work hardening. Plastic anisotropy is modelled from the materials crystallographic texture by a visco-plastic self-consistent polycrystal-plasticity code VPSC.

Abstract: In the current work, the recently proposed homogeneous anisotropic hardening (HAH) model, featuring a distorted yield surface, is applied to commercially pure aluminium. A dislocation-based hardening rule is incorporated into the HAH model to describe the transient stagnation of the hardening rate during strain reversal. A cast and homogenized material with random texture previously investigated by Mánik et al. [1] is selected. The material is prestrained either by compression or rolling, and then tested in uniaxial tension to acquire either reverse softening or orthogonal hardening. The Bauschinger effect, the permanent softening during reverse loading and the hardening in the course of orthogonal loading are captured by the model. However, the permanent softening during orthogonal loading cannot be predicted, and the transient variations of the R-value predicted by the HAH model are neither in qualitative nor quantitative agreement with the experimental data.

Abstract: Anisotropy of the plastic properties is an index of sheet’s ability to stamping. In this work the transverse deformation coefficient and r-value were used. Uniaxial test was made for annealed pieces of 1 mm thickness from aluminum alloy AA2024, steel X10CrNiTi18-9, Titanium Grade 2 and titanium alloy Ti-2Al-1Mn. Pieces were cut at angle of 0, 22.5, 45, 67.5 and 90O to the rolling direction. Steel pieces have anisotropy coefficients practically independent from angle between it’s’ axis and the rolling direction. Pieces made of AA2024 cut at angle 45О to the rolling direction have largest anisotropy coefficients. Titanium alloys have the largest coefficients for angle 67,5О between axis of piece and the rolling direction. Both indexes of anisotropy are higher for titanium alloys, which is property of HCP-metals.

Abstract: The continuous annealing process was simulated on the heat treatment system for thin steel sheet (CCT-AY-II). As the recrystallization was known, the annealing temperature and holding time were taken into account to study the influence on microstructure and mechanical properties of 0.08mm ultrathin cold-rolled SPCC steel. Combined with transmission electron microscope (TEM), the precipitation behavior was analyzed. The optical micrographs show that the microstructure of the samples are more similar to batch-annealing steel rather than general specification SPCC steel through continuous annealing. With 5°C/s heating rate and annealed at 860°C for 80s, the sample performs best: the yield strength is 161MPa, the elongation is 29% and the r-value is 1.51. AlN and MnS precipitations are observed in the inner grain and at grain boundary. The annealed textures mostly composed of {111} texture. The highest intensity is centered around the {111}<110> orientation.

Abstract: Insulation is considered one of the effective solutions to achieve energy savings in buidings. Better insulation having low thermal conductivity contributes significantly to new construction and retrofitting existing buildings. The Energy Conservation Building Code and National Building Code of India define the prescriptive and mandatory requirements for the U-factor and R-values for different climates but the way to achieve these values is left to the designers. As none of the walling and roofing assemblies in buildings fulfill the criteria for overall thermal transmittance, the study deals with determining the thermal conductivity of sustainable walling materials and prefab roofing technologies as well as insulating materials using Guarded Hot-Plate Apparatus. The MATLAB program is developed for computing the U-values and for predicting the desired retrofit insulation thicknesses to make different materials and roofing assembly combinations comply the Code requirements in different climatic regions of India. The results of the study are used for computing the performance with and without insulation using DesgnBuilder software for improving energy efficinecy of the buildings in composite climate in India.