Tooth root crack is considered as one of the crucial causes of failure in the gearing system and it occurs at the tooth root due to an excessive bending stress developed in the root region. The modern power transmission gear drives demand high bending load capacity, increased contact load capacity, low weight, reduced noise and longer life. These subsequent conditions are satisfied by the aid of precisely designed asymmetric tooth profile which turns out to be a suitable alternate for symmetric spur gears in applications like aerospace, automotive, gear pump and wind turbine industries. In all step up and step down gear drives (gear ratio > 1), the pinion (smaller in size) is treated as a vulnerable one than gear (larger in size) which is primarily due to the development of maximum root stress in the pinion tooth. This paper presents an idea to improve the bending load capacity of asymmetric spur gear drive system by achieving the same stresses between the asymmetric pinion and gear fillet regions which can be accomplished by providing an appropriate addendum modification. For this modified addendum the pinion and gear teeth proportion equations have been derived. In addition, the addendum modification factors required for a balanced maximum fillet stress condition has been determined through FEM for different parameters like drive side pressure angle, number of teeth and gear ratio. The bending load capacity of the simulated addendum modified asymmetric spur gear drives were observed to be prevalent (very nearly 7%) to that of uncorrected asymmetric gear drives.

The thermal residual stresses generated during curing process of laminated polymer composites can negatively affect their mechanical strength and performance. Premature failure, delamination, out-of-plane deformation and matrix cracking are negative effects of residual stresses. In order to predict the residual stresses effects on the performance of composite components, it is important to develop techniques to measure those stresses. The slitting method is one of the most conventional methods of residual stress measurement. In this method, a slit is created incrementally through the thickness of the stressed part and the released strains in each incremental depth are then measured by a strain gauge. A major assumption of this method is that the measured strains during the slitting experiment are only caused by the residual stress component perpendicular to the slit face. However, slitting process will also release two shear stress components in the slit plane, which may influence the values of the measured strains. This paper investigates the effect of the released in-plane and out-of-plane residual shear stresses in the slitting process on the measured strains for a carbon/epoxy laminate as well as a steel specimen. The results of the finite element simulations show that both components of the residual shear stress may significantly affect the measured strains during the slitting experiment. For simultaneous determination of residual normal and shear stresses, a new method using two strain gauges attached in both sides of the slit is presented. Finally, the validity of the simulation results was demonstrated by carrying out the slitting experiments on two carbon/epoxy composite specimens.

Forming limit Curves are one of the common tools to predict the necking in various forming processes. In this study, the Marciniak-Kuczynski instability theory by applying the Gotoh yield function is utilized to estimate the forming limit curves for the AA6016-T4 aluminum sheet in plane stress conditions. Also, the effect of three different hardening models including Swift, Voce, and a linear combination of the Swift and Voce models to determine the limit curves are investigated. The comparison between the theoretical forming limit curves and experimental results from the Nakajima test determines the accuracy of the hardening models in predicting the limit strains. Since in many new forming processes such as hydroforming and incremental sheet forming processes, investigation of the process in plane stress state is not an exact assumption, Therefore, in continuation of the paper, generalized forming limit curves are plotted based on the developed Marciniak-Kuczynski model by extending the Gotoh yield function, and the effect of compressive normal stress and through-thickness shear stress on forming limits of the sheet are investigated. The results indicated that by applying the compressive normal stress and through-thickness shear stresses, the limit strains increase, and the formability is improved, in contrast, limit stresses move down in the diagram.

The present work tries to obtain a simple means of simultaneous measurement of steady shear viscosity and normal stress difference in polymer melts and high concentrated solutions. The task is performed by using a rotating rod viscometer. In the experiments the steady shear viscosity is obtained by the measurement of the torque and the normal stress difference obtained by measuring the free surface height developed due to the rod climbing (Weissenberg Effect).A one dimensional unsteady modeling of the nonlinear viscoelastic flow using Leonov model will enable us to obtain the time dependent torque and the free surface height at various shear rates for a given fluid. Hence, the device is calibrated for a known fluid, and by using the calibration curves and reading the torque and free surface height, the steady shear viscosity and the normal stress di1terence could be obtained for any fluid by using the obtained numerical simulation data.

An investigation was carried out to assess the subsurface suitability of the River Nzoia floodplain in Budalangi Division of western Kenya for supporting shallow foundation structures. An analysis of the conditions in the area during flood seasons was conducted using soil mass characterisation, geotechnical testing, slope stability analyses, terrain evaluation and analysis of ground conditions in buildings in the area. The analyses reveal that significant slope failure occurs when the percentage of water exceeds 50% in slopes cut at angles greater that 24°. The suitability of the ground for supporting shallow foundation structures has been established from the results of fieldwork and from laboratory studies.

Analysis methods proper to the level of design and the type and configuration of the dam are used for evaluating the concrete dam response under static and dynamic loadings. The amount of tensile stresses that occur inside the dam body has been very important to assess the safety of suchlike structures during earthquake. In this study, two- dimensional finite element model of the tallest monolith of Javeh RCC dam was provided for the purpose of analysis. The hydrodynamic effect of the reservoir was applied by solving the wave equation. The assumptions of water compressibility and structure deformation were used in the analysis. The foundation rock underlying the dam and reservoir bottom was modeled as a homogeneous, isotropic and viscoelastic half- plane. Static analysis results show that the compressive stresses exist in the whole of the dam body. In the dynamic analysis subject to maximum credible earthquakes, principal tensile stresses of some elements at the downstream face of the dam are greater than allowable tensile stress of RCC. Normal tensile stresses are less than the tensile strength of RCC layers.

Title: Proteomics Studies in Abiotic StressesIntroduction: The increase in the world's population, along with climate change, which reduces the efficiency of agricultural products, is a major challenge for food security. Abiotic stresses such as drought, salinity, heat and cold cause many changes in the physiological, biochemical and molecular processes of plants. By knowing the role of proteins expressed in response to stress, the mechanisms and processes of stress tolerance can be accurately and comprehensively analyzed and evaluated. Also, by discovering new stress-resistant proteins, it is possible to improve stress resistance in transgenic plants with genetic engineering and genome editing methods and increase yield performance. The study of proteomics as a powerful tool for the separation and detection of stress-responsive proteins will help us in this way.Materials & Methods: This article is a review paper that was obtained by searching related articles on reliable sites (Google Scholar, Web of Science, PubMed, Scopus, SID). Research findings: Proteomics studies have led to the identification of several biological and physiological pathways responsible for tolerance to abiotic stresses in different plant species. In this regard, the identification of genes encoding the proteins involved in these processes as well as the transfer and overexpression of these candidate genes in plants is an effective strategy to improve stress resistance in economic agricultural products. In addition, the differential expression of genes in response to different stresses showed that some proteins have the same morphological and physiological manifestations in response to multiple stresses applied to them.