Article history: Received 6 January, 2015 Accepted 2 June 2015 Available online 4 June 2015 The aim of this research is to investigate the impact of crumb rubber and Styrene-ButadieneStyrene (SBS) on rutting potential of porous asphalt mixtures. Optimal binder content of control mix, 5% SBS, and mixtures containing 10%, 15%, and 20% of crumb rubber were determined using Cantabro Loss test. Dynamic creep, wheel tracking, draindown, and fallinghead permeability tests were then carried out on specimens to examine rutting resistance, resistant to draindown, and permeability. SBS modified and 10% rubberized asphalt satisfied all the requirements of porous asphalt design criteria. They also have similar rutting performance, permeability. Except for rutting performance, 10% rubberized asphalt has the best performance. Instead, asphalt mixture containing 20% crumb rubber was the most mixture against rutting resistance. © 2015 Growing Science Ltd. All rights reserved.

In the present paper, the differential transformation method is employed to develop a semianalytical solution for free transverse vibration of single-walled carbon nanotube (SWCNT) with arbitrary boundary conditions.The small scale effect is taken into consideration via Eringen's nonlocal elasticity theory while the transverse shear deformation effects and rotary inertia are taken into account in presented Timoshenko beam theory.Through variational formulation and the Hamilton's principle the governing differential equations and the boundary conditions are derived and then solved by a semi-analytical method called differential transformation method (DTM) for various frequency modes of beams and different edge conditions.Comparisons made between the present results and results reported by well-known references for special cases treated before, have confirmed accuracy and efficiency of the presented approach.The effects of several parameters such as transverse shear deformation effects, slenderness ratios, boundary conditions and small scale on vibration characteristics of SWCNT are examined.The present study illustrates that the vibration characteristics of an SWCNT are strongly dependent on the small scale parameters.

Article history: Received September 6, 2014 Accepted 12 November 2014 Available online 12 December 2014 In this paper, a volume criterion based on a simple scalar quantity, the mean value of the strain energy (SED), has been used to assess the static strength of notched components made of Polymethylmethacrylate (PMMA). The local-strain-energy based approach has been applied to a well-documented set of experimental data recently reported in the literature. Data refer to blunt U-notched cylindrical specimens of commercial PMMA subjected to static loads and characterised by a large variability of notch tip radius (from 0.67 mm to 2.20 mm). Critical loads obtained experimentally have been compared with the theoretical ones, estimated by keeping constant the mean value of the strain energy in a well-defined small size volume. In addition, some new tests dealing with V-notched specimens with end holes have been carried out to investigate the effect of the notch opening angle. © 2015 Growing Science Ltd. All rights reserved.

Zirconia/ veneer bi-layered components are extensively used in dental restoration technology to improve resistance of tooth's surface from decay.The direction of the fracture propagation at the interface of zirconia and veneer is investigated in this paper.Finite element analysis is performed on a bi-material four point bend specimen in different geometries, and the fracture initiation angle is obtained using maximum tangential stress (MTS) criterion.The effect of specimen geometry on the fracture initiation angle is discussed.Because an interface crack may propagate through interface or kink into one of the materials, some comments are given to determine under which condition "interface de-bounding" will be happened.

In this paper, the effects of specimen size and crack length on the fracture toughness of polycrystalline graphite are studied. The experimental results reported in the previous studies showed that the fracture toughness of graphite increase in bigger specimen. It has been also demonstrated that the fracture toughness of graphite is nearly identical in specimens with crack length ratio less than 0.7 but decreases for grater crack length ratios. To justify the size and crack length dependency of fracture toughness, the modified form of maximum tangential stress (MMTS) criterion, which makes the use of higher order terms in calculating the stress field around the crack tip is employed. It is shown that the MMTS criterion can provide good estimates for the fracture toughness of graphite obtained from specimen with different sizes. It is also indicated that the MMTS criterion can predict very good the reported experimental fracture toughness data for samples with the crack length ratios less than 0.7.

The fatigue failure around rail-end-bolt holes is particularly dangerous since it leads to derailment of trains and consequently to inevitable accidents.It is well-known that the fatigue life of structural holed components, subjected to cyclic load, can be increased by generating compressive hoop stresses around the holes.These beneficial residual compressive stresses significantly reduce the maximum values of the operating tensile stresses arising at the critical points of the components and thus impede the formation of first mode cracks.A new approach to enhancement of fatigue life of rail-end-bolt holes has been developed.The approach involves sequential drilling and reaming through a new combined tool and then slide diamond burnishing by a new device.The technology implementation was carried out on machine tool.The process of creating residual stresses has been studied both experimentally and numerically.The experimental study was conducted by means of a modified split ring method.A reliable finite element modeling approach to the slide diamond burnishing process was developed.On this basis, the process was optimized by means of a genetic algorithm.As a result, the optimal combination of the governing process parameters is established, which ensures both maximum depth of the compressive zone and maximum absolute values of the residual stresses.

Article history: Received January 20, 2014 Received in Revised form April, 10, 2014 Accepted 15 April 2014 Available online 17 April 2014 Lightweight concrete is a suitable constructional material, which can decrease the weight of buildings and the hazards of earthquake loads. Hence, a large number of research studies have been focused on designing and manufacturing high strength lightweight concretes. In this research using the natural and industrial lightweight aggregates frequently found in the south-east region of Iran (Kerman province), high strength and low cost light weight concretes were manufactured. The effects of aggregate type, aggregate size, and concrete mixture were studied experimentally on the compressive strength of concretes and the density and cost of manufactured samples. © 2014 Growing Science Ltd. All rights reserved.

Beams are the constituent elements of several machine parts and sophisticated structures. In this paper, efforts are made to develop suitable methods that can serve as the basis to detect crack location and to crack size from measured axial vibration data. This method is used to address the inverse problem of assessing the crack location and crack size in various beam structure. The method is based on measurement of axial natural frequencies, which are global parameter and can be easily measured from any point on the structure. In theoretical analysis, the relationship between the natural frequencies, crack location, and crack size has been developed. For identification of crack location and crack size, it was shown that data on the variation of the first two natural frequencies is sufficient. The experimental analysis is done to verify the practical applicability of the theoretical method developed.

Article history: Received January 20, 2014 Received in Revised form April, 10, 2014 Accepted 7 May 2014 Available online 9 May 2014 Stroke is one of the main causes of disability. It affects millions of people worldwide. One symptom of stroke is disabled arm function. Restoration of arm function is necessary to resuming activities of daily living (ADL). Along with traditional rehabilitation techniques, robot-aided therapy has emerged recently. The control schemes of rehabilitation robots are designed for two reasons. First they are designed for passive rehabilitation in which the robot guides the patient's limb through a predefined path and second for active rehabilitation in which the patient initiates the movement and is partially assisted or resisted by the robotic device. This paper introduces a new robot for shoulder rehabilitation. The Shoulder Rehabilitation System (SRS) has three degrees of freedom (DOFs) for three rotational DOFs of the shoulder but additional translational DOFs of the shoulder are also allowed to avoid discomfort to the patient. A new open circular mechanism is proposed for the third joint that solves the known issues for rehabilitation robots such as long wiring and discomfort associated with closed mechanisms. Lyapunov-based controller with integral action is proposed to guide the robot through a predefined trajectory. Simulation results proved that the proposed controller can track the desired trajectory; reject constant bounded disturbance to the system and is robust due to its nonlinear nature. The proposed controller is designed to be used in passive rehabilitation. © 2014 Growing Science Ltd. All rights reserved.

A B S T R A C T In this paper, a differential quadrature element method (DQEM) is developed for free transverse vibration analysis of a non-uniform cantilever Timoshenko beam with multiple concentrated masses. Governing equations, compatibility and boundary conditions are formulated according to the differential quadrature rules. The compatibility conditions at the position of each concentrated mass are assumed as the continuity in the vertical displacement, rotation and bending moment and discontinuity in the transverse force due to acceleration of the concentrated mass. The effects of number, magnitude and position of the masses on the value of the natural frequencies are investigated. The accuracy, convergence and efficiency of the proposed method are confirmed by comparing the obtained numerical results with the analytical solutions of other researchers. The two main advantages of the proposed method in comparison with the exact solutions available in the literature are: 1) it is less time-consuming and subsequently moreefficient; 2) it is able to analyze the free vibration of the beams whose section varies as an arbitrary function which is difficult or sometimes impossible to solve with analytical methods. }}