An investigation into the MIXED MODE fracture of steel fiber reinforced concrete (SFRC) beams with one percent volume fraction of steel fiber is presented. A series of notched beams with different notch depths and locations are tested under three-point bending. The test results for apparent fracture toughness, crack trajectories, and fracture energy are presented. The crack paths for SFRC and plain concrete beams are compared. The apparent fracture toughness values were more scattered for SFRC than for plain concrete. The load-deflection curves were used to obtain the fracture energy.To this end, two methods were utilized for center notched beams, and the results were comparable to each other. It is observed that fracture energy is a more reliable material property than apparent fracture toughness, and its scatter is less.

In this article, stress analysis of an isotropic infinite cylinder weakened by multiple concentric cylindrical cracks subjected to shear and radial loadings on the lateral surface of the cylinder is accomplished. First, relations for stress and displacement components are given in terms of the Galerkin biharmonic vector potential. Next, using these relations, the dislocation solutions for both Somigliana and Volterra dislocation are derived. Using the distributed dislocation technique, integral equations for the infinite cylinder with arbitrary number of the cylindrical cracks are constructed. The numerical solution of resulting integral equations which are of the Cauchy type singular equations leads to evaluation of Somiglianaand Volterra dislocation densities on the crack surfaces. Using related dislocation densities, the stress intensity factors of crack tips for some examples are attained and variations of them with lengths of cracks are discussed. For some special cases, validation of the results of this study with others available in the literature is done.

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.

Fracture of MIXED MODE I/II in beech wood and its wood polymers has been investigated experimentally in this study. Hence, two crack systems of TL and RL were selected in which the crack planes extend along the wood fibers. This investigation has demonstrated that onset of MIXED MODE cracking can be predicted with a very simple fracture criterion in these crack systems. Results indicated that fracture critical loading is affected by furfurylation and also load-displacement curves of specimens were changed. Variations in fracture toughness values of MIXED MODE I/II can be occurred following variations of fracture critical forces. In the both crack systems, KIC/KIIC distribution trend is changed by furfurylation that indicates changing of material nature by furfurylation. Results of scanning electron microscopy (SEM) analyses indicated that micro cracks occurrence in wood polymer structure may be one of the factors caused to change in fracture toughness, these changes occur simultaneously with material nature modification followed by increasing of shear strength parallel to the grain due to polymerization.

A millimeter wave H-plane duplexer with E-plane filters has been designed. The channel filters are connected via a T-junction which is compensated by a cylindrical post and analyzed by integral contour method.Moreover, the junction discontinuity effects have been taken into account. The combination of filters and compensated T-junction allows for low-cost manufacturing. The E-plane filters are analyzed separately, by the MODE matching method. The scattering parameters of the combination of filters and T-junction are obtained. The diameter and position of the compensating post and the length of the T-junction arms are optimized in order to achieve the desired performance. This procedure saves computational time and memory. The duplexer has been built for 38GHz and the theory was verified by measurements.

Elliptical subsurface cracks are one of the probable types of cracks that occur in engineering structures. Due to the non-symmetrical geometry with respect to the crack surface, coupling of the fracture MODEs occurs in an elliptical subsurface crack and so, the crack under normal loading will experience all fracture MODEs. MODE III caused by the coupling effect under normal loading is negligible whereas MODE II is significant. In this paper, MIXED MODE two dimensional weight functions of the elliptical subsurface cracks parallel to the surface are derived for aspect ratios of a=0.2, 0.4, 0.6, 0.8, 1.0 and ratios of crack depth to crack length of =0.05, 0.06, 0.08, 0.1, 0.14, 0.2, 0.3, 0.5, 1.0. MIXED MODE stress intensity factors under uniform normal loading are used as reference stress intensity factors. By curve fitting on the calculated weight functions coefficients, the derived weight functions are able to be used for any α and. To verify the weight functions, the stress intensity factors of all points of the crack front are calculated under linear, elliptic paraboloid and trigonometric paraboloid stress distributions and compared to the finite element results. Comparison of the results shows high accuracy with mean relative error less than 7%. Using derived weight functions, MIXED MODE stress intensity factors of the subsurface elliptical crack can be determined for any α and  and under any normal stress distributions.  

In this work, a cabinet solar dryer for thin layer drying of Cuminum cyminum was evaluated in two conditions (Indirect and MIXED). Four levels of drying air flow rates (three active and one passive) were adopted. The experiments were performed in a completely randomized Block design pattern in three replications. Drying durations were kept constant (90 min) for all the experiments. Average initial moisture content of Cuminum cyminum was 43.5% (db) and the product was set to be dried for 90min in the solar dryer (average 8%d.b). The effects of the drying air flow rates and MODEs of drying were highly significant in final moisture content of Cuminum cyminum. Duncan test was selected to evaluate the effects of different factors on average moisture content of the samples. The results showed that the passive air flow system in MIXED MODE drying conditions for drying the Cuminum cyminum was best. The drying duration for the mentioned condition was 55min to dry the product from 43.5% to 8% (db). The experiments were conducted each sunny day of August-September 2007 from 11.30 till 13.The average solar irradiance was recorded 750 W/m2; average ambient air temperature was 32oC; and average ambient relative humidity was 20%. Using the dryer in the best selected conditions reduced the moisture content of the product from 43.5% to 4.95% after 90 min.

In the present research, the MIXED-MODE fracture mechanics analysis in a plate with central hole under tensile loading is considered. It is assumed that a plate containing two symmetrical hole-edge cracks is bonded with two dissimilar planes. The stress intensity factors at the crack tips are calculated. The problem is MODEled in Casca software and this MODEl is analyzed with Franc software. The effects of various factors such as hole diameter, crack length, angle of crack and material properties of plates have been investigated on stress intensity factors. The stress intensity factors increases with increasing crack length. Also, the stress intensity factors increases with the increase of hole diameter. For a certain amount of for small crack lengths the effect of cracks length on variation of stress intensity factors is more than the hole diameter but for large crack lengths the effect of hole diameter on variation of stress intensity factors is more than the cracks length.

This paper has been presented according to the importance of crack bridging in MIXED MODE I/II delamination of laminated composites and it is aimed to understand the physics of crack bridging. Firstly, the most important micro-mechanisms involved during fiber bridging are introduced. To do this, interlaminar fracture tests have been performed on composite specimens. Also, the fracture surfaces and the damage zone on the edge of the specimens have been observed using a scanning electron microscope (SEM). In the following, due to the complexity of the existing bridging MODEls and the difficulty of determining their various parameters, a novel approximate method has been presented. In this method, which is based on a more complex physics-based MODEl, the bridging laws are extracted by preserving the physics of the problem and considering simple approximations. The main advantage of the proposed method is the achievement of bridging laws using simpler relationships with fewer required parameters. Finally, the validity of the method has been evaluated through a comparison of the traction-separation behavior predicted by the proposed approximate bridging laws with the experimental traction-separation curves in different MODE mixities.

Thin reinforced plates are utilized widely in many fields of engineering industries. Existence of crack is an important factor of failure in such structures, which can lead to structural damage in less time than its real function without the crack. In this paper, stress intensity factors for MODE one and MODE two of fracture are studied in isogrid thin plate reinforced with diamond lattice and stiffeners with T-shaped cross section under uniaxial and biaxial loading conditions to find the difference with simple plates. The rectangular reinforced plate has 12 stiffener ribs with angle of 60 degrees regarding to transverse axis. In order to MODEl the reinforced sheet, plates and stiffeners are assembled together uniformly. MODEling and analysis are performed using Abaqus finite element software; and the effect of various parameters such as length and angle of the crack and also, the different loading conditions on stress intensity factors in reinforced lattice plane are investigated. The results show that each of the investigated variables has a significant impact on stress intensity factors. Also, by changing the angle of crack or at different loading conditions, the stress intensity factors can have negative values in lattice reinforced thin plate.