An analysis of the two concepts the failure and crack propagation in various materials has always been of interest to researchers. Thus, it is of necessity to investigate the failure of constru(CT)ion steel as one of the most widely used materials in the industry. Numerical modeling is always a compliment to the analysis of laboratory samples. One important issue, particularly in failure problems, is to study the behavior of laboratory samples according to their dimensions. In the current research, the effe(CT) of sample thickness size on crack tip behavior is numerically examined. A standard (CT) SPECIMEN is commonly used to evaluate the failure of du(CT)ile materials. The crack tip behavior along the thicknesses of the laboratory samples is a combination of plane stress and plane strain behavior. Accordingly, in the present study, the effe(CT) of thickness on the numerical samples was investigated via the numerical result validation. The validated results then were used as a complement to the experimental results. Modeling and analysis of the numerical samples of varying thicknesses indicated that, with progression from the sample thickness center towards the free edges, the behavior shifts from plane strain to plane stress. In the case of the standard (CT) SPECIMEN with 25 mm crack length, the samples with greater than 15 mm thickness have an almost plane strain behavior, and the results are proved to be reliable. Then, with further analysis and taking into account the parameters dependent on sample size, loading value, and stress-strain values perpendicular to the equation plane, an equation was presented which can be used to realize to what extent the behavior in the free edge of the (CT) SPECIMEN operates in the form of plane stress or plane strain.

Mode I fra(CT)ure toughness (KIC) is one of the most important parameters in the fra(CT)ure mechanics of brittle material. Several laboratory methods have been suggested to determine the mode I fra(CT)ure toughness. However, many of these methods deal with the lengthy sample preparation procedure, premature failure of samples, and difficulties in obtaining the precise value of the fra(CT)ure toughness property. In this paper, a recently proposed pseudo-COMPA(CT) TENSION method is used to evaluate mode I fra(CT)ure toughness of a middle-grain granite benefiting the advantages of this method including; simplicity of the test, high level of test control, and high accuracy of the KIC value. For this purpose, granite samples in four different diameters and with six test repeats per diameter have been prepared and tested using the pseudo-COMPA(CT) TENSION method. For each sample, in addition to recording the load and displacement data, the acoustic events during the loading process were also recorded simultaneously by an acoustic emission equipment. First, the resulting fra(CT)ure toughness value for each sample has been determined, then the size effe(CT) has been evaluated and analyzed. Finally, the results of the acoustic emission method, as the monitoring tool in the fra(CT)uring process of tested samples, have been analyzed. The qualitative evolution of acoustic emission parameters well illustrates the mechanical process occurring in the tested samples with well-matched coinciding with the mechanical transitions observed in samples during the loading process. Experimental results show that mode I fra(CT)ure toughness is positively related to the SPECIMEN size and there is a noticeable size effe(CT) in KIC value up to a certain diameter.

In this paper the critical strain energy release rate for T300/913 carbon-epoxy laminated composites has been studied using ANSYS finite element software based on virtual crack closure technique (VC(CT)). COMPA(CT) TENSION ((CT)) SPECIMEN has been used for numerical analyses and the geometrical dimensions have been extra(CT)ed from the existing references. The results obtained from the finite element analysis are compared with the existing experimental results in literature. There is good agreement between the critical energy release rate obtained from finite element analysis and the experimental results. Accuracy and simplicity of presented model make it appropriate for predi(CT)ing the experimental results and improving experimental techniques. The innovation of the present research is the simplicity of the model for simulation of the critical strain energy release rate of the laminated composites.

Mode I fra(CT)ure toughness (KIC) is one of the most important parameters in fra(CT)ure mechanics, which represents the ability of a material containing a pre-existing defe(CT) to resist tensile failure. In this paper, the crack length effe(CT) on the mode I fra(CT)ure toughness of an isotropic homogeneous material was investigated. For this purpose, several disc shaped PPMA samples were loaded in pure TENSION by performing pseudo-COMPA(CT) TENSION (p(CT)) tests. Digital image correlation (DIC) method was utilized to assess and monitor the distribution of the deformation field during the tests. DIC results were also used to compare the effe(CT) of crack length on the deformation field variation in samples. Very good agreement was found between the KIC values estimated in this study and those reported in the past for the similar material,indicating that the p(CT) method is convenient for the assessment of KIC. The experimental results also show that the initial crack length has a tangible impa(CT) on KIC, although the magnitude of its influence is closely related to material stru(CT)ure and type. According to the tests results, an increase in the initial crack length leads to increase the ultimate displacement at failure point, decrease the maximum load and the amount of absorbed energy until the moment of failure, and finally decrease the mode I fra(CT)ure toughness of the material. Results of this study show that the p(CT) method configuration is useful for testing PMMA and may be useful for testing other materials suitable amenable of molding such as mortar, concrete and ceramics. According to the comparison of the results, in the optimum range of sample diameter, about 50 mm, the initial crack length is suggested between 11. 5 to 15. 5 mm for the PMMA.

This research work presents the study on fra(CT)ure behavior of Al6061 with graphite particulate composite produced by the stir casting technique. The materials sele(CT)ed for the proposed work is Al6061 and graphite particles. COMPA(CT) TENSION ((CT)) SPECIMENs were utilized to determine fra(CT)ure toughness for different thickness of composite. In the present work, optimizing the parameters of the COMPA(CT) TENSION SPECIMENs is carried out using Taguchi method. Four parameters and two fa(CT)ors are considered to optimize the parameters. Fa(CT)ors considered are material composition and a/W ratio. From the Taguchi analysis, on COMPA(CT) TENSION SPECIMENs, Al6061-9%graphite is the optimized composition and fra(CT)ure toughness is maximum for a/W ratio = 0. 45. All the COMPA(CT) TENSION SPECIMENs of different thickness (B = 4, 5, 7, 10, 12, 15, 18 and 20mm) of a/W=0. 45 were tested to find the fra(CT)ure toughness. From the results, it was observed that the Kq reduces with increment in thickness to width (B/W) proportions and found to stay consistent for B/W≥ 0. 3. This consistent estimation of Kq for B/W≥ 0. 3 prevail the plane strain fra(CT)ure toughness (KIc) of the composite.

Background and Aim: This study was condu(CT)ed to evaluate the safety and efficacy of TENSION-free Tape for the surgical treatment of female stress urinary incontinence.Materials and Methods: In a prospe(CT)ive open study for pre and post operative, we followed 36 patients at least 1.5 years after surgery (18-28 months); all patients underwent the operation under local anesthesia, allowing the surgeon to check intra-operatively that continence has been obtained.Results: Mean operation time was 36 minutes (range 20-45 minutes). 32(89%) of the patients was cured according to the protocol, another 3(8.3%) were significantly improved and there was 1 (2.7%) failure. Mast of patients (about 91%) were operated on a one day-care basis, which implies that they were released from the hospital the day after the procedure, and no post operative catheterization, defe(CT) healing and tape reje(CT)ion occurred. Pain free recovery time without any analgesic was another benefit.Five patients needed an indwelling catheter for 3 days and two uncomplicated hematoma occurred.Conclusion: Based on the results, we conclude that TENSION-free Vaginal Tape is a safe and effe(CT)ive ambulatory procedure for surgical treatment of genuine stress urinary incontinence, which allows the majority of the women to be discharged from the clinic the day after the procedure and start their works in the second week.