Bitumen plays a significant role in our daily lives, primarily used in road construction. The main source of bitumen is oil refineries, and bitumen from Qayyarah is considered an important resource in Mosul. The oil from Qayyarah is a heavy crude with an aromatic origin, and the high-productivity bitumen can be extracted from it, reaching up to 48% and more than a thousand tons daily. However, it fails the indirect Tensile strength Tests of the asphalt mixtures used in road paving. We attempted to improve its engineering properties, particularly by increasing the indirect Tensile strength, using three treatment methods for Qayyarah bitumen, so it remains competitive in the Iraqi market by utilizing cheap and readily available materials like elemental sulfur, low-density polyethylene waste, and C9 petroleum resin, each mixed in two different ratios for processing to reduce industrial operation costs. Our goal was to help Qayyarah bitumen succeed in the engineering mixtures, with the added ratios being 1% and 2% for elemental sulfur, low-density polyethylene, and petroleum resin C9. The results were excellent, showing a clear improvement in the indirect Tensile strength Test of the asphalt mixtures, an increase in their load-bearing capacity (Marshall Test), and homogeneity in Scanning Electron Microscope (SEM) images. The prepared samples did not suffer from phase separation and were within the allowable range.

Introduction Determination of the mechanical properties of rock materials has been remained as a challenge for engineering geologists. In-situ Tests are rarely used to determine the mechanical properties of rocks due to difficulties in sample preparation, performing and interpretation of the results, high costs as well as the required long time for doing the experiments. The common approach to determine the mechanical properties of rock materials is through conducting laboratory experiments and estimation the in-situ properties based on these laboratory results. This approximation, which is called scale effect, has been remained as a challenge for engineering geologists and practical rock engineers for decades...

In the present work, hot Tensile behavior of Haynes 25 Co-base alloy was investigated in the temperature range of 950-1200 ˚ C and 0. 1 s-1. Thermodynamic calculations showed that M23C6 and M6C carbides were stable below 1000 ˚ C and above 1050 ˚ C, respectively. Stress-strain curves also indicated an unusual trend of strain fracture. It was observed that with increasing temperature from 950 to 1050 ˚ C, the fracture strain was decreased, while it was raised above 1050 ˚ C again. Increasing the volume fraction of M6C carbide rich in Tungsten resulted in the loss of ductility. Also, microstructural evaluations showed dynamic recrystallization (DRX) grains were nucleated and growth was around carbides and the initial grains at 1150 ˚ C. Occurrence of DRX led to the improvement of ductility via grain refinement mechanism, so this alloy had the highest level of ductility at 1150 ˚ C

In this paper, the nonlinear elastic behavior of pericardium of human, canine, calf and ostrich was studied. For this purpose, the mechanical behavior was investigated from two viewpoints of the Cauchy and Green elastic materials. Firstly, the experimental data were fitted by Cauchy elastic stress equation. The results showed that the response of Cauchy elastic materials was not fitted with the experimental data appropriately. Secondly, the Green elastic materials were studied by assuming strain energy functions for the mechanical response of the samples. For this purpose, the exponential-exponential, power law-power law, and exponential-power law energy functions were investigated by mathematical programming. It was observed that all energy functions were fitted with the experimental data accurately, especially the power law-power law function. Finally, it was observed that the Green elastic materials theory was more appropriate for studying the mechanical behavior of pericardium by comparing the experimental and theoretical results.

Rutting is one of the most important deteriorations in flexible pavements and a significant amount of annual maintenance and rehabilitation funds are spent for its repair. Permanent deformations increases, which leads to increasing rut depth, can cause irrepairable problems in asphalt pavements. On the other hand, in Marshall method, which is known as the main method of asphalt mixtures mix design in Iran, the lack of a simple Test to determine specimen resistance to permanent deformation is sensible. Although there are many devices to measure the rutting nowadays, but none of them have the ability to be used at site level. In addition, prevalent methods of evaluating rutting potential of asphalt mixtures are usually expensive and time consuming. The abovementioned factors necessitate development of a simple laboratory method that not only enjoys an acceptable precision but also is able to predict specimens rutting performance with low cost within the short time. In this research, one type of aggregate, one type of gradation, two types of bitumen, one type of filler, and three bitumen contents were used to prepare Marshall asphalt mixture specimens. After performing the main Tests on specimens, IDT Test results and Marshall parameters were used to develop a mathematical model to estimate specimen Wheel Track apparatus rut depth. The presented model measures rutting resistance using a combination of indirect Tensile strength Test results and Marshall parameters. The model is validated using artificial neural network, which makes it possible to evaluate rutting potential while OBC is being determined in a laboratory. Therefore, not only is there no need for expensive instruments of rutting Test, but also a remarkable time saving in mix design procedure is achievable.

Nowadays, the need to enhance the exploitation of hydrocarbon resources due to importance and increase in the rate of consumption of this material is more crucial than ever. On the other hand, the rock formations with low effective porosity, which are considered as hydrocarbon reservoirs prevented to have a suitable productivity of these reservoirs. Hydraulic fracturing is known as a process of initiation and propagation of fractures caused by fluid injection into the part of the boreholes in rock formations, which has an important role in increasing of the exploitation of hydrocarbon reservoirs with low efficiency. Initiation and propagation fractures have a high dependency to the parameters and properties of reservoir rocks. Among these parameters can mention, such as rock material, rock Tensile strength, pore pressure and etc. Importance Tensile strength of rock for predicting the breakdown pressure of hydraulic fracturing Test is remarkable and this parameter is a function of lithology of reservoir rock. Hence, in this study with sampling at typical section of Asmari formation, evaluation of breakdown pressure parameter as a function of rock Tensile strength and lithology parameters has been paid. The ratio of hydraulic fracturing Tensile strength to Brazilian Test Tensile strength and Point load Test allows prediction of the Tensile strength and is an important parameter for simulation of hydraulic fracturing Test results. Comparison of these ratios shows that the Tensile strength parameter is dependent on the Test method. Rock Tensile strength that obtained from hydraulic fracturing Test is 20.08 MPa and proportion between Tensile strength of hydraulic fracturing Test to Brazilian Test is equal to 2.35. Slight differences in the distribution of data and regression coefficient 0.9 are due to the small karst cavities, relatively low porosity and intragranular voids because of fossils in the rock structure. All evidences, including the results of physical and mechanical properties reveal the influence of lithology on the results of Tensile strength obtained from hydraulic fracturing Test.

Background & Aim: Mechanical properties of cerebral arteries are relevant to cer ebrovascular diseases.Methods & Materials/Patients: To acquire these properties, eight samples were obtained from the middle cerebral arteries of human cadavers, whose deaths were not as a result of injuries or cerebrovascular diseases, and were Tested within twelve hours after resection, by using a precise biaxial Tensile Test device specially developed for this study. The dimensions, sensitivity and anisotropic nature of samples were considered. The resultant stress stretch curve was plotted and, subsequently, fitted to a hyper elastic three-parameter Fung model.Results: It was found out that the arteries were noticeably stiffer in circumferential direction than in axial direction. It was also demonstrated that the use of multi-parameter hyper elastic constitutive models was useful for mathematical description of behavior of cerebral vessel tissue.Conclusion: The reported material properties were a proper reference for numerical modeling of cerebral arteries and computational analysis of healthy or diseased intracranial arteries.

ABSTRACTThe Tensile strength of high-strength bolts is determined by two Test methods. In the first method, the Tensile strength of the bolt is determined using a nut. The second method uses the device introduced in ISO instead of the nut. In the Tested bolts, two failure patterns are observed,the bolt thread stripping and fracture in the threaded length of bolt. In this research, in addition to the experiment, the elastic-plastic numerical simulation of the bolt failure pattern was also performed in Finite element software. The results of the study show that the frequency of the thread stripping failure pattern is 4% in the bolt tension Test with the ISO device and 90% in the bolt tension Test with the nut. In addition, the Tensile strength obtained from the bolt tension Test with a nut is lower than the bolt tension Test method with the ISO device. According to the frequency of the failure pattern in each method, the bolt tension Test with the ISO device leads to the determination of the Tensile strength of the bolt material, and the bolt tension Test with the nut leads to the evaluation of the Tensile strength of the bolt and nut assembly. Due to the compatibility of bolt and nut performance in steel structure, this research suggests performing Tensile Test of bolt and nut, in addition to other Tests.Keywords:Bolt Failure Pattern, Thread Stripping, High-Strength Bolt, Bolt Tensile Test, Tensile Strength.Introductionbolts are one of the most important components of a bolted connections, and its failure will be more destructive than the failure of other components, and even the failure caused by the weakness of the bolts in the connections can be progressive. Therefore, the importance of bolt inspection reveals the need for more accuracy and study in this field. In case of inaccuracy in the selection of bolts, contrary to expectation, a lower level of safety will be achieved. Therefore, not paying attention to any part of the inspection process of bolts will cause errors in the Test results, and ultimately this will cause wrong approval to be issued for the use of rejected bolts in the structure. The Tensile strength Test of bolts is done in two common ways in laboratories. In this study, while performing both common methods of Testing the Tensile strength of Bolts, the frequency of failure patterns in each method was investigated. In this regard, the previous related studies and the statistics and frequency of each pattern were examined in the Test methods. Numerical simulation was also performed for both Tensile Test methods.2. Methodology2.1. Prerequisite Tests for Testing the Tensile strength of boltsIn this study, before performing the Tensile Test, Decarbonization Test (ISO 898-1, 2013), Charpy impact Test at -20 degrees Celsius (EN ISO 148-1, 2016), Proof load on the nut (ISO 898-2, 2012), was conducted on both specimens. The reason for conducting these three Tests was that the results of the experimental failure pattern belonged to the bolts according to the standard, and possibly the results of the non-standard bolts should not be relied upon, and thus the health of the bolt and nut threads was examined as much as possible. In all three mentioned Tests, all the specimens confirmed the standard conditions.2.2. Common Tests to determine the Tensile strength of boltsThe Tensile strength of high-strength Bolts is determined by two Test methods. At first method, the Tensile Test is doing with bolt and nut and but by second method, ISO 898-1 (2013) device fastended instead of nut on the bolt. On the Bolts fracture, observed two damage Pattern, the thread striping and fracture in the threaded length of bolt (Fig 1).3. Results and discussionTo evaluate the frequency of the failure pattern in the two Test methods, the statistics of the failure pattern in the two Test methods were collected and analyzed from several laboratories (fig 2).4. ConclusionIn this research, according to the results obtained from the laboratory investigation, the frequency of the failure pattern and the numerical simulation, we obtain the following important results:• Bolt performance in joints is more conformity with bolt-to-nut Tensile Testing.• The Tensile strength of the bolt with nut is lower than the Tensile strength of the bolt with the ISO 898-1 device, and it will not be correct to refer to the number obtained from the Tensile Test with the ISO 898-1 device as the Tensile strength of the bolt and nut set.• Pre-tensioning or over-tightening will cause the thread stripping and the strength of the bolt to decrease significantly. This defect does not have any visible symptoms and therefore it can be frequent.• The shortness of the bolt length can reduce the Tensile strength of the bolt and nut and thread stripping when pre-tensioning the bolt.Based on the results of this research, the Tensile Test of bolt with nut is suggested, in addition to other Test methods.5. ReferencesISO 898-1: 2013 (E), 2013. Mechanical Properties of Fasteners Made of Carbon Steel and Alloy Steel.ISO 148-1: 2016 (E), 2016. Metallic materials — Charpy pendulum impact Test —ISO 898-2: 2012 (E), 2012. Part 2: Nuts with specified property classes —Coarse thread and fine pitch thread.

The rapid growth of traffic, especially heavy vehicles passing by repeated loading, poor quality asphalt mix and not reaching different the required density of asphalt pavement can cause asphalt damage. One of the most important types of flexible pavement failures, is permanent deformation, which are known by the name rutting. Rutting is done by aggregation of Permanent deformation and irreversible through the pavement layers under traffic loading repeated. Through the all different layers involved in rutting, permanent deformation in the surface layer of pavement is allocated to the main contribution of rutting, thus Provide an appropriate mix design, attention to the potential risk of permanent deformation asphalt mixtures that weakness indication shear resistance in the asphalt is essential to be considered. On the other hand the specified flow number is beginning marker for Shear deformation in asphalt mixtures is known as a marker for evaluation of asphalt mixtures rutting. In this study, we have tried to build the asphalt samples with Marshall method, that including range of the aggregates, asphalt, aggregate, filer and bitumen percentage with the development of a relationship between obtained flow number from the dynamic creep Test, Tensile strength from indirect Tensile Test and the parameters of the Marshall mix design while providency administrative costs, predicted the mixture rutting status, without spending extra time. The accuracy of this model was confirmed by the artificial neural network, makes it possible to prevented produce concrete with low shear resistance in the laboratory and before factory manufacture. Thus, considerable savings in future time and costs there would be in mix design.

This paper puts forward a novel numerical-experimental method for calculation of constants of advanced anisotropic yield criterion BBC2003. Calculation of the eight constants of this yield criterion demands experimental determination of eight mechanical properties of the material. These properties include: axial-yield stresses in 0, 45 and 90o with respect to the rolling direction, anisotropic parameters in the directions mentioned and plane strain yield stresses for 0o and 90o orientations. However, determination of the equi-biaxial yield stresses and anisotropic coefficients is relatively expensive. In the method presented in this paper, using a simple technique, the constants of the yield criterion are calculated based on plane strain yield stresses in 0o and 90o to the rolling direction. The system of equations involving the conTestants of the yield function is solved numerically through defining an error function and minimizing it using steepest descent method. In two case studies, the constants of BBC2003 yield criterion for anisotropic sheets of aluminum alloys AA3105 and AA6061-O, were calculated using this method. Subsequently, the accuracy of perdiction of axial-yield stress and anisotropic coefficient in different directions as well as the coincidence of yield surface with experimental results for BBC2003 and Hill48 yield criteria have been investigated. The results show that the proposed method has good accuracy and stability in calculation of advanced yield criterion constants and consequently the mechanical properties of anisotropic sheets in different directions.