In this paper, the MIXED-MODE dynamic fracture analysis of a FGM plate is performed using MLPG method also the effect of changes in value and angle of material gradation on the dynamic Stress Intensity Fctor (SIF) of MODE I, II, and effective are investigated. To solve time dependent equations that discretized by MLPG method, the Central Difference Method (CDM) and the Newmark method are used. Although the J integral is one of the most common methods to calculate the SIF, but in general, it is not applicable for FGMs. So, in this paper the path independent integral, J*, which is formulated for the nonhomogeneous material is used to calculate stress intensity factor. Results show that the present method has good agreement with the exact and other existent solutions. Results also, show the maximum and minimum values of effective stress intensity factor for E2/E1>1 are occurred at material gradation angle equal to 0o and 90o respectively, and for E2/E1<1, vice versa.

Automatic crack propagation and stable fatigue crack growth as complicate problems in fracture mechanics are studied. In this study The Extended Finite Element Method (XFEM) is utilized because of several drawbacks in standard finite element method in crack propagation MODEling. Estimated Crack paths are obtained by using Level Set Method (LSM) in coupling with XFEM for 2D MIXED MODE crack propagation problems. Stress intensity factors for MIXED MODE crack problems are numerically calculated by using interaction integral method completely based on familiar path independent J-integral method. Different crack path growths are shown for different types of boundary conditions. Also, stable fatigue crack growth due to numerous cycles of loading using Paris law is presented. Finally, some experimental results and analytical solutions for stress intensity factors are concerned to guarantee the numerical estimated crack path growths and stress intensity factors respectively.

In inclined U-notches, the MIXED MODE (I+II) loading occurs and the MODE ratio can be increased by varying the notch angle. In this paper, the effect of the inclined U-notch geometry, i.e. the notch depth, the notch angle, the notch root radius, and the position of the notch with respect to supports, on the MODE ratio (KII/KI) have been studied. Three-point bending and plane strain condition have been considered in this study. Finite element results using ANSYS have shown that the MODE ratio increases by increasing the notch root radius. Also, it has been found that the MODE ratio decreases by increasing the distance of the notch from the supports, and by increasing the notch angle. However, it is seen that the notch depth has complicated effect on the MODE ratio. The variation of the MODE ratio with respect to the notch depth has a relative maximum and a relative minimum.

In this paper, the equivalent layup method to estimate the delamination initiation of asymmetric double cantilever beam (ADCB) is presented. A relation for critical strain energy release rates (SERR) of unidirectional (UD) and multidirectional (MD) laminates, as a criterion for crack growth initiation, was presented. For finite element analyses, the ADCB specimens were MODEled in ABAQUS/Standard software and SERR is determined using the virtual crack closure technique (VCCT). According to this method, the ability of estimating delamination initiation without using experimental tests and finite element MODEling of MD specimens is provided. This method reduces the volume of calculations FEM and experimental tests significantly. Accuracy of the proposed method has been verified by experimental data. Also, the total strain energy release rate analyzed by this method is compared with the FEM and theoretical results. Results show that SERR of MD lay-ups can be predicted by measuring SERR of the unidirectional specimens using FEM method with an error less than 10%.

An interaction integral method for evaluating MIXED-MODE stress intensity factors (SIFs) for two dimensional crack problems using NURBS-based isogeometric analysis method is investigated. The interaction integral method is based on the path independent J-integral. By introducing a known auxiliary field solution, the MIXED-MODE SIFs are calculated simultaneously. Among features of B-spline basis functions, the possibility of enhancing a B-spline basis with discontinuities by means of knot insertion makes isogeometric analysis method a suitable candidate for MODElling discrete cracks. Moreover, the repetition of two different control points between two patches can create a discontinuity and also demonstrates a singularity in the stiffness matrix. In the case of a pre-defined interface, non-uniform rational B-splines are used to obtain an efficient discretization. Various numerical simulations for edge and center cracks demonstrate the suitability of the isogeometric analysis approach to fracture mechanics.

Based on preliminary investigations under controlled condition of drying experiments, a MIXED-MODE solar dryer with forced convection using smooth and rough plate solar collector was constructed. This paper describes the development of dryer considerations followed by the results of experiments to compare the performance of the smooth and the roughed plate collector. The thermal performance of solar collector was found to be poorer because of low convective heat transfer from the absorber plate to air. Artificial rib roughness on the underside of the absorber plate has been found to considerably enhance the heat transfer coefficient. The absorber plate of the dryer attained a temperature of 69.2oC when it was studied under no-load conditions. The maximum air temperature in the dryer, under this condition, was 64.1oC. The dryer was loaded with 3 kg of grapes having an initial moisture content of 81.4%, and the final desired moisture content of 18.6% was achieved within 4 days while it was 8 days for open sun drying. This prototype dryer was designed and constructed to have a maximum collector area of 1.03 m2. This solar dryer been be used in experimental drying tests under various loading conditions.

ABSTRACT: Modal split MODEls, as the third step in the four-step transportation MODEling framework, determine the share of different travel MODEs. Choice MODEls as probability MODEls have been used in recent decades and have faced significant progress. The MIXED logit MODEl has been known for many years, but has only become fully applicable since the advent of computer and simulation technology. This MODEl can approximate various random utility MODEls according to the accuracy required, through adopting appropriate distributions for attributes coefficients in the utility function. The purpose of this research is to present a MIXED logit MODEl structure for MODE choice, in order to describe the taste variation among individuals and the source of the variation in response to the various attributes that influence the MODE choice. The required data is from Mashhad O-D survey in 1387 and MODEl calibration is executed in Biogeme software. Results of MIXED logit MODEl indicates among passengers a taste variation in choosing between a personal car and motorcycle, based on car and motorcycle ownership. The source of this taste variation is MODEled and captured through random coefficient analysis. Finally, it is shown that MIXED logit MODEls are superior to multinomial logit MODEl with a confidence level of 99 percent. The superiority is however small, partly due to the inadequacy of the aggregate data.

Present study deals with the prediction of crack initiation angle for MIXED MODE (I/II) fracture using finite element techniques and J-Integral based approach. The FE code ANSYS is used to estimate the stress intensity factor numerically. The estimated values of SIF were incorporated into six different crack initiation angle criteria to predict the crack initiation angle. Single edge crack specimens of Araldite-Hardener were used for the present analysis. Load was applied up to critical limit of the specimens containing crack at different angles of inclination. The crack initiation angle obtained using stress intensity factor and J-integral based approach were found close to each other and also found to be in good agreement with the available experimental results in literature. It is also investigated that as crack inclination angle increases material was found to behave in a brittle manner.