Advanced Engineering Forum Vol. 31

Abstract: Solids show the feature of internal friction and the feature of fatigue. As a cause for the both features we assume the migration of atomic items. The driving forces for the migration of the atomic items can be mechanical stress gradients and temperature gradients. In an earlier publication formulas have been derived for the internal friction and for the fatigue. From these formulas follows a relation between internal friction and fatigue. The mechanical stress gradients are the cause of the background of internal friction which shows a monotonous rise with temperature. Temperature gradients in the solid can be produced by total internal friction. In contrast to the background of internal friction the temperature dependence of the total internal friction shows maxima and minima. Because of the relations between internal friction and fatigue the temperature dependence of fatigue shows that the fatigue is caused by temperature gradients. The relation between internal friction and fatigue also shows the influence of the internal friction on the fatigue curve.

Abstract: The following study involves designing of a go-kart chassis using CAD and CAE tools. The chassis is the supporting base for every automobile and chassis is subjected to various loads due to self-weight, acceleration, braking, bumps and cornering. CATIA Software was used for designing the CAD model of the chassis and ANSYS software was used for the FEA analysis of the chassis under different loading conditions. The calculations of these forces due to impacts are required to design a functional chassis for go-kart and having an adequate stiffness to avoid any vibration or resulting resonance. Ten mode shapes and natural frequencies are studied for vibration characteristics using Modal analysis in ANSYS. For impact analysis the loads in terms of gravitational acceleration are applied for the front, side and rear impact as 4g, 2g and 2g respectively and the results are compared to get the best material among the four selected materials AISI 4130, AISI 1080, AISI 1020 and AISI 1026.

Abstract: Mortar is a workable paste essential in civil and building construction. Mortar works as binding material extensively use for masonry unit in construction. The global consumption of natural sand is very high, due to the extensive use of concrete or mortar. Natural sand deposits are being depleted and causing a serious threat to the environment as well as the society. Sandy clay has been widely use in preparing the mortar for masonry work. The aim of this research was to study the bending strength of built-up masonry prism using sandy clay mortar. There were two series of mortar containing 0% and 100% of sandy clay had been prepared. The sandy clay was used to replace natural fine aggregate. Mortar with 0% sandy clay was the control mix containing 100% natural fine aggregate. Three types of masonry unit consist of clay brick, cement brick and lightweight brick were used in this study. The masonry units were combined together using the mortar joints to form the masonry prisms. 100% natural fine sand and 100% sandy clay mortar were prepared and used for the joints. Built-up masonry prisms with single and double joints of mortar. Also, the masonry prisms contained from a length ranging from 390 mm to 610 mm were prepared using the mortar joints. The thickness of the mortar joint which was used in this study was 10 mm, 20 mm and 30 mm. the prisms had been tested for the determination of bending strength at 28 days. The experimental results were analyzed to investigate the effect of sandy clay and thickness of mortar on the bending strength of built-up masonry prism. Results had shown that masonry prism built with sandy clay mortar has higher bending strength compare to the fine sand mortar. Clay brick exhibited highest bending strength with sandy clay mortar which was 38.28 N/mm² and cement brick had the lowest bending strength which was 18.8 N/mm², while cement brick achieved optimum bending strength. In addition, the highest collapse and deflection achieved by clay brick and cement brick whereas the lowest value of collapse and deflection was by lightweight brick. The highest percentage of increment in terms of collapse load was determined to be 13.73% for sandy clay mortar prism. Hence, 100% sandy clay mortar is suitable to be used in masonry works.

Abstract: In this study, geopolymer samples were prepared by mixing metakaolin (MA) with activator solution made of potassium alkali silicate solution, potassium hydroxide flakes, and additional water. The aim of the experiment is to evaluate the mechanical strength of hardened samples based on four test variables including the SiO₂/K₂O molar ratios, K₂O concentration, H₂O/MA water coefficient, and curing temperature. The results reveal that K₂O concentration and H₂O/MA water coefficient impact strongly on the compressive strength, whereas varying of SiO₂/K₂O molar ratios in the range from 1.0 – 1.4 does not significantly change the compressive strength of geopolymer samples. On the other hand, high-temperature curing leads to higher mechanical strength of the samples in the early-age compared to curing at room temperature, due to the faster establishment of hard structure in the early-age of geo-polymerization process. However, curing at a temperature range of 80°C – 100°C contributes the non-linear strength development of the samples over the time.

Abstract: Clever decision making in the selection of building materials is a topic that focuses on important aspects of the building industry.‏ The materials used in the facade of the building not only affect the appearance of the building and the city but also affect the environmental, social, economic, energy efficiency and other kinds of aspects. Considering the importance of this issue, in this research, the city of Tehran‏ was studied in terms of building materials and tried to solve the problems of Tehran by identifying and analyzing the current situation. Statistical analysis was performed using R software packages version 3.5.0 and Microsoft Excel. The most important result of the data is that travertine has been identified as the most commonly used material in Tehran since the past 10 years. In this research, after examining the various types of materials used in the facade of the buildings in Tehran, we seek to discover the relationship between the type of building materials and the building age. In addition, after examining sample buildings, several common types of combinations of materials have been presented in the facades of Tehran's buildings. Keywords: building materials, building facade, travertine

Abstract: It was investigated the effect of die channel angles and their combination on plastic deformation of pure copper during ECAP under friction and frictionless conditions using 2-D elastic-plastic finite element modelling. A sound knowledge obtained for the plastic deformation (material flow) and understood the relationships between plastic deformations. The modelling results suggested that strain inhomogeneity was lesser in channel angle 120^o than channel angle 90^o and pressing load as well as strain decrease with increasing die channel angle. The friction influence in case of combination of channel angles was negligible as compare to individual channel angles. The strain generation and distribution was more uniform in case of combination of channel angles as compare to individual channel angles.

Abstract: In this study, a novel fuzzy behavioral TOPSIS model was proposed. Sensitivity analysis is conducted according to the behavioral TOPSIS model parameter (λ) for the different case studies taken from the literature. The ranking results are slightly different according to different λ values. The results of the study can be used in material and manufacturing method selection problems.