mohammadreza mohammadaliha

By taking into consideration the consequences and rise in soil alkalinity that is a result of industry growth and reliance on fossil fuels, evaluating the reasons that lead to concrete degradation and deterioration was considered crucial. For this purpose, the mechanical behavior of fiber concrete under unstable environmental conditions was probed. Concrete composites with varying percentages of steel and glass fibers and no fibers were analyzed. Compressive, indirect tensile, and fracture toughness properties were evaluated using the Edge Notched Disc Bend (ENDB) test under freezing-thawing and acidic environments and the results were compared with normal conditions. Steel fibers decreased the strength in the specified cycles, while glass fibers showed a normal strength trend. Samples containing 1% of steel fibers showed a 15% increase in fracture toughness compared to 2% of these fibers in 300 cycles, while the strength of samples containing 1% of these fibers increased by 22% in the non-cycled state.

Pavements that are directly exposed to environmental and traffic conditions are thus exposed to many factors that cause erosion and deterioration. As the road passes through different areas along the route, these destructive factors also change. Factors such as soil, traffic conditions, rain, frost and etc. damage the coating and thus shorten its service life. One of the appropriate ways to study the influence of the aforementioned factors on the crack propagation process in rigid and flexible pavements is the science of fracture mechanics. Fracture mechanics is the science that studies cracked components, including laboratory samples of pavements, and uses its parameters, including toughness and fracture energy, to study the behavior of asphalt and concrete pavements against crack growth and propagation. The aim of this paper is to review studies in different crack growth environments, focusing on new samples, including SCB and ENDB specimens. A review of these studies will help improve future research on pavement damage mechanics. Considering the increasing growth of concrete pavements, especially roller compacted concrete pavements (RCCP), it is recommended that further research be conducted on the crack growth behavior of these pavements. The use of ENDB specimens in dealing with the failure mechanics of different load status has also been recommended in various studies related to pavements due to the ease of performing the tests.

Freeze-thaw cycles are among the most important climatic factors that change the mechanical properties of pavement concrete, and play an important role in creating cracks and also affect the growth mechanism of cracks. Concrete pavement damage caused by environmental factors including daily and seasonal fluctuations in humidity and temperature profiles, changes in groundwater level, precipitation/ infiltration, freeze-thaw cycles and other external factors, are completely modeled in the mechanistic-empirical design method (ME). The effects of melting and freezing are experienced in the substrates, but ultimately cause damage to the pavement surface. In order to analyze the sensitivity of JPCP concrete pavement to freeze-thaw cycles, in this study, the sensitivity of the resilient modulus (Mr) of the base material against these cycles and also against the groundwater level was analyzed using enhanced integrated climate model (EICM). For this purpose, the fluctuations of modulus adjustment factors (F_env) against various variables such as technical characteristics of base materials, number of days elapsed since ice melting, groundwater table level and saturation degree of materials were calculated and then, the sensitivity of the base layer resilient modulus to changing the adjustment factors was evaluated. Then, using the normal sensitivity index (NSI), the change in the damage potential of this type of pavement was analyzed. The results showed the potential for vulnerability of jointed plain concrete pavement (in terms of faulting, cracking and roughness) to freeze-thaw cycles to be "Extremely Sensitive".

The production of parts using 3D printing, which is a type of additive manufacturing, is expanding at a faster rate. This technology can produce complex geometries by depositing melting polymer material layer by layer. Polylactic acid (PLA) is one of the most widely used materials in this technology due to its good properties such as biodegradability and bio-compatibility, and parts manufactured with PLA are being used in various engineering applications. The strength of these layer-by-layer parts depends on the printing parameters such as the infill density, the orientation of the printed fibers, the speed and temperature of the print, the distance between the fibers, etc. Also, the presence of grooves in engineering parts, especially printed polymer layer-by-layer parts, can significantly affect the mechanical behavior of these materials. In this research, the strength of short grooved beam parts with three different geometries (U, V, key hole) printed with PLA material under quasi-static bending loading is investigated experimentally and statistically. The amount of load and fracture energy of the samples are measured and also the sensitivity to the geometry of the groove in the tested parts is evaluated. Fisher's test is used for pairwise comparison of the grooves' strength. The results of this research show that the groove with an angled corner is the weakest, while the circular groove has a higher resistance, and this resistance increases when the radius of the circle is increased.

Recycling and reusing materials have received much attention from researchers in recent decades. Today, environmental issues have become very important due to the limitation of available resources as well as the increase in the cost of new materials. Since most of the existing roads in Iran have flexible pavements, using reclaimed asphalt pavement (RAP) and using fewer new materials can be considered an environmentally friendly solution. In recycling asphalt pavements, there is a major concern related to low-temperature cracking. The purpose of this research is to investigate the low-temperature cracking properties of asphalt mixtures containing RAP along with other additives to introduce a mixture with performance characteristics equivalent to the new asphalt mixture. For this purpose, asphalt mixtures with two different contents of RAP (25% and 50%) were considered. Also, to improve their adhesion properties, the addition of a rejuvenator (10% by weight of RAP binder as the optimal percentage) and to improve the resistance of the mixture against cracking, crumb rubber (10% by weight of new binder) was considered. An indirect tensile strength test and a semi-circular bending test (SCB) were performed to investigate the properties of the mixtures. Also, the crack mouth opening displacement (CMOD) during the SCB test was measured through imaging. According to the SCB test, adding RAP to the base sample reduces the fracture energy. But adding rejuvenator and crumb rubber to the recycled samples improves the properties of the mixture against crack growth. The results showed that the asphalt mixtures containing RAP and additives, according to the tests used in this research, presented equal or even better performance than the new asphalt mixture. Also, the combined index of fracture energy - CMOD can be used as a suitable criterion to investigate the effect of RAP, rejuvenator and crumb rubber in asphalt mixture.

This research examines the vibrations of multi-layer aluminum-metal fiber cylindrical shells with embedded piezoelectric layers that have fluid-structure interaction based on the three-dimensional elasticity theory. Using the state space approach, the equations of motion for simple support boundary conditions were obtained. The natural frequencies of the multi-layer metal fiber cylindrical shell containing the driving fluid were obtained by solving the special frequency equation. The effect of different parameters such as length to radius, fluid velocity, ambient wave number and radius to thickness was investigated for aluminum reinforced with carbon fibers. The volume ratio of composite/metal was considered constant. So far, no research has been done on multi-layered aluminum fiber-metal cylindrical shells with embedded piezoelectric layers that have fluid-structure interaction. It is a very new topic. The consistency and convergence of the results of this research was confirmed by comparing the results of natural frequencies reported in the literature, and the high accuracy of the results of this research is expressed.

The durability of asphalt mixtures depends to a large extent on the asphalt film thickness. Stripping is the separation of the asphalt binder film from the aggregate surface due to the action and penetration of water. In this study, a gradation was prepared from basalt crushed aggregates. Then, by applying upper and lower allowable deviation tolerances to the fine aggregates of it, two gradations were produced. Nano-Organosilane Zycotherm was used as a liquid antistripping additive.  The guidelines of the MS-2 Journal of the Asphalt Institute, NCHRP 567 report, Austroads and VicRoads reports were used to calculate the asphalt film thickness. Scanning Electronic Microscopy (SEM) was also used to show the asphalt film thickness of the three asphalt mixtures. The Marshall Stability Ratio and Indirect Tensile Strength Ratio tests according to AASHTO T283 were used to evaluate the moisture durability of asphalt mixtures. The results showed that the gradation changes in the fine aggregates caused a 12.9% decrease in asphalt film thickness in asphalt mixtures with upper allowable deviation tolerances and a 17.7% increase in asphalt film thickness in asphalt mixtures with lower allowable deviation tolerances, and these changes necessitate durability tests.  Also, in the evaluation of moisture durability, all three asphalt mixtures were able to strip according to MSR and TSR indexes. Although Zycotherm had a positive effect on the MSR index of all three asphalt mixtures, according to the TSR index, the asphalt mixture with the lower allowable deviation tolerances was still able to stripe. Therefore, the moisture damage due to the gradation changes in this asphalt mixture is not improved by the Zycotherm additive.

This article examines the effect of layer arrangement and fiber angles on the vibration behavior of cylindrical shell (FML) in GLARE and ARALL samples and on Pasternak elastic bed with different boundary conditions using 3D elasticity theory (composite/metal volume ratio is fixed in taken). The governing equations are obtained using the potential energy minimization principle. In order to ensure the accuracy and convergence of the results of this study, the numerical solution was done using the Finite Element Method (FEM). The results show that the layering has a great influence on the vibration behavior of the FML cylindrical shell. The results are in good agreement with other literature. The use of three-dimensional elasticity theory along with the analysis of different samples for the vibrations of reinforced FML shells, which is presented for the first time in this research, is one of the most important innovations of the current research, and these results can be used as a suitable criterion for analyzing and optimizing FML shells. It can be used with any number of metal and composite layers, any fiber placement angle and under any boundary conditions.

Manufacturing polymer concrete (PC) with suitable performance against cracking is an important issue for using these composite materials in practical applications. Fracture toughness and fracture energy of such randomly distributed aggregates inside the matrix of polymeric resin is affected by the mix design and percentages of PC ingredients. In this research, the optimum composition of epoxy base PC mixture made of four ingredients (epoxy resin, fine and coarse silica aggregate) was obtained using a L8 Taguchi design of experiment method. Some fracture toughness tests under mode I were conducted on Single edge notched bending specimen according to design of experiment suggested by Taguchi method. The initial range for each PC ingredient was selected as: 25-31% fine aggregate, 21-23% epoxy resin, and 46-54% coarse aggregate, and it was found that the mixture containing maximum resin (23%), maximum fine filler, minimum percentages of fiber and coarse aggregate can provide the highest fracture energy and fracture toughness values.

The use of resin based cement is a common method for strengthening and retaliation the damaged bones material. However due to lack of sufficient adhesion in the interface of two materials (i.e. bone and injected cement) a crack can be initiated in the interface and consequently it can be fractured due to application of external loads to the repaired bone part. In order to investigate the load carrying capacity and reliability of bi-material joint of bone's soft tissue-hydroxyl apatite cement, a number of bi-material bone-cement specimens in the shape of circular disc containing a center crack in the interface of disc and subjected to diametral compression were tested. The bi-material specimens were load under different inclination angles of crack related to the loading direction. This results in application of different mixed mode I+II (i.e. tensile-shear deformation) in the interface of center crack. The results showed that the fracture load and fracture energy becomes more by increasing the crack inclination angle (i.e. increasing the contribution of shear mode deformation relative to mode I component). In addition the overall strength of bi-material bone-cement system was higher than the neat one material bone material. The fracture of all tested bi-material samples was extended along the interface line of Brazilian disc specimen with no kinking into any of two bone or cement materials.

The use of Edge Notched Disc Beam (ENDB) sample has been proposed as a suitable geometry in performing fracture tests in different loading modes. The most important features of the ENDB samples include easy making, quick and easy sampling, simple testing, and the ability to examine a wide range of pure and combined loading modes. Using a wide range of fracture tests, a statistical model is proposed to predict the stress intensity factors of asphalt mixtures in terms of the pure torsion mode (mode III) loading in this study. To this end, the experiments were carried out at different temperature conditions (-5, -15 and -25 °C), different loading conditions (0.5, 1 and 5 mm/min), and on control and modified asphalt mixtures with different percentages of polyolefin-aramid fibers. The results showed that, with increasing the fiber content and loading rate, the fracture strength increased with average 25%, while an increase in fracture toughness due to lower temperature had an effect of less than 5%.  Using the Response Surface Method (RSM), the prediction model of stress intensity coefficients of asphalt mixtures was presented in the pure torsion mode. The results of the proposed models had a good correlation with the results of the conducted fracture tests.

Cracking of asphalt layers and pavements is one of the most common modes of failure in roads and highways, which can significantly increase the costof repair and rehabilitation. Since asphalt mixtures can behave as brittle materials at low temperature,brittle fracture and crack growth in pavements is usually observed at the surface of roads located in cold regions. Traffic loading (due to the weight of moving vehicles) and thermal stress (induced by daily or seasonal variations of field temperature), are two major parameters affecting nucleation and propagation of cracks inside the pavements. Reflective cracking is often observed in the overlays, and the growth of such cracks is an important problem in field. In this paper, a multi-layer asphalt pavement containing a reflective crack is analyzed and fatigue life, crack path and effective stress intensity factor are determined. Using extensive two-dimensional finite element analyses, the effect of modulus and thickness of overlay and existing asphalt layer on fatigue life of asphalt pavement were investigated. The results demonstrate that exceeding the thickness of overlay from a special amount causes abrupt increase in the fatigue life of asphalt pavement and also the HMA stiffness were the most influencing factors on the pavement fatigue life. Among the mechanical and geometrical properties of asphalt layers, overlay thinness has the most impact on the crack growth path. By increasing overlay thickness the crack grow path will have a smaller deviation from vertical direction.

Innovation governance refers to the active role of the government in the innovation system where it should pave the way for innovations via participatory decision-making, cooperation between those in power, as well as developing and proposing clear goals and targets that make it possible to design appropriate policies for innovation. Most of the problems and challenges that counties, especially less developed ones, encounter in terms of innovation are related to innovation governance. Furthermore, the first step in promoting and enhancing innovation governance is to know countries’ current status. Therefore, the purpose of this research was to identify and prioritize indicators for evaluation of innovation governance at macro level. To that end, first, the available literature was reviewed and experts were consulted to extract the indictors for evaluation of innovation governance at macro level. Then, these indicators were weighed and prioritized using fuzzy SWARA.finally, using the main indicators of innovation governance at the Macro Level As well as analyzing the policies applied in science, technology and innovation, the status of Turkey's innovation governance as a developing country whose experiences in science and technology policy making could be useful to the Islamic Republic of Iran was examined.

In this paper, an inventory model for deterioration items in a two-echelon supply chain including one retailer and one manufacturer is proposed by considering the stock and price dependent demand and capacity constraint for holding inventories. First, the model is presented as a leader-follower game in which the manufacturer announces wholesale prices. Second, the retailer decides for the order quantity and price of the items based on the wholesale prices. Then, by introducing the integrated model of the supply chain, a cost-sharing contract is applied to coordinate the manufacturer and the retailer. On the other hand, by using the convergence properties of the model and proving non-concavity of the problem, a meta-heuristic algorithm, namely iterative local search (ILS) is proposed to solve the models. The results show the determinant role of the capacity constraint on the optimal decisions and the ability of the proposed contract to coordinate the supply chain. Moreover, it is shown that the proposed algorithm outperforms the well-known interior point algorithm as the results of the initiations embedded in it for the special problem.

Concrete is one of the most widely used building materials for fragile behavior. The addition of fiber to concrete affects the behavior of tensile strength, tensile strength, flexural strength, modulus of elasticity, impact resistance and some other mechanical properties of concrete. For this purpose, an experimental research was carried out to provide an experimental model of the flexural fatigue life of reinforced concrete with macrosynthetic fibers by constructing concrete joists with three different thicknesses of 80, 100 and 150 mm. SN models (stress-loading) and HN (thickness-loading) was presented. The results showed that increasing the thickness of concrete samples and adding fibers to concrete mixture increases the fatigue life. Also, the addition of fibers to concrete samples measured the thickness of the sample for the stress level of 0.7 final stresses at 12.45-8.24%, for the stress level of 0.8, the final stress was 22.15-5.45%, and for the stress level of 0.9, the final stress decreased to 22.15% -10.18% Finds. Fiber-reinforced concrete is a type of concrete that is mixed with fiber. Various types of fibers are used to produce fiber-reinforced concrete, which include glass, polymer, carbon and steel. In the present research, macro-synthetic polymer fibers were used. Some of the consequences of applying macro-synthetic fibers in concrete include reduced shrinkage of fresh and hardened concrete, increased ductility, increased strength against fatigue stresses, increased durability and lifetime of concrete, improved concrete mechanical properties (tensile strength, flexural strength, etc.), control of secondary/thermal cracks of concrete, preventing the in-depth propagation of cracks, post-cracking chargeability and reduced permeability against chloride and sulfate ions .In most of the studies, the concrete sample's thickness is increased along with the increase in the beam's length; however, in the present work, only thickness of the beam samples with and without fibers was changed and other dimensions of the samples were kept constant in order to investigate merely the effect of increased thickness. Accordingly, effect of the size of macro-synthetic fiber-reinforced concrete sample at different thicknesses was assessed via fatigue life variations. The intertwisted fibers were added to the concrete mixture by 0.4 vol.%. Then, from each sample, three specimens were made. The obtained results were averaged and, then, recorded in the relevant tables. The following cases were considered as the research - Effect of sample size on fatigue life of concrete samples - Effect of adding macro-synthetic fibers on fatigue life In order to determine flexural fatigue of the concrete samples with the above-mentioned geometric properties, UTM device was used. The test was performed with constant sinusoidal loading at the frequency of 10 Hz. The input information for the test included loading curve shape, minimum and maximum loading values, loading frequency, and maximum number of loadings, all of which were defined as the input. To measure the values of stress levels in order for measuring the loading values, first, the average of the samples' flexural strength had to be determined; then, the stress levels could be calculated from the obtained results. also A cross sectional analysis of the broken sample showed that most of the sample failure was from aggregate and the mixture design was suitable.

By the research on the behavior of fracture toughness in asphalt mixtures, it has been suggested that several components have been proposed to test the mode III (KIIIc) fracture toughness of asphalt mixtures. But until now, a standard piece not been provided for testing fracture toughness (KIIIc) of asphalt. Such specimen should have appropriate geometric and loading conditions. In addition, it could be compatibility with the most common features in the inherent of tested materials and provide repeatable, reliable and integrity data of fracture resistance in asphalt mixture. ENDB is one of the specimens that could provide these items for calculating KIIIC of asphalt materials. It seems to be a good choice in comparing with other samples due to advantages such as ease of construction, cracks creation and simulation facilities of mode I loading for investigating of asphalt fracture behavior. The aim of this study was to investigate the effect of geometry and characteristics of asphalt mixtures on the behavior of ENDB fracture toughness. Using the finite element software (ABAQUS), geometry and meshing of the desired part have been performed. The result of this research can help in selecting and introducing the appropriate standard specimen and appropriate specifications of asphalt mixtures to determine the amount of KIIIC of asphalt mixtures to researchers. The important results of this research can be mentioned as the effect of thickness on the degree of fracture toughness in loading mode III. So the fracture toughness in the specimen with a higher thickness increases, and with the decrease in the percentage of air void and the test temperature, the degree of toughness of the fracture also increases.

This paper describes an evaluation of low temperature cracking of asphalt pavement and its propagation agents. Low temperature cracking is one of the noticeable deterioration of asphalt pavement in cold climate regions. This work employed a repeatable semi circular bending (SCB) fracture test to evaluate the low temperature fracture resistance of asphalt mixtures, additionally a large number of edge cracked semi circular bend specimens containing 4% and 7% air voids are used and subjected to symmetric three-point bending load at -10 °c to measure fracture toughness. The effect of air voids on pure mode I asphalt fracture are investigated experimentally and Linear Elastic Fracture Mechanics, its assumptions and effective crack tip parameters introduced, which is used in asphalt fracture mechanics. Then fracture toughness as a main parameter of fracture in the asphalt mixtures is calculated and various methods with different specimen types for determining the fracture toughness of asphalt has been viewed and Asshto suggested method has been discussed, which applied to the experimental part of this work. According to the statistical principle, the experimental results were analyzed by Weibull statistical distribution model in order to present the prediction models for each asphalt mixture with different air voids. The two-parameter and the three-parameter Weibull distribution function was applied to air voids data, Thus compared these two functions. Within the statistical analysis, the probability function for brittle fracture suggested by Wallin using a Weibull analysis that have the three parameters, Kmin, m and K0 ,all of which predicted in this study.
The analysis of the results also revealed that Weibull distribution model is one of the most appropriate function for disscussing the volumetric properties of asphalt mixtures.Furthermore, a statistical analysis illustrated that Weibull model is also able to predict the statistical parameters for each set of test data, By preliminary data from the tests and also a well- defined Transfer Coefficient from the previous experimental data that the other researchers obtained through their studies, can be predicted the three-parameter and the two-parameter of Weibull statistical model such as Kmin and K0 which have significant role for asphalt fracture mechanics. In addition to the parameters of Weibull distribution, the average fracture toughness or the average stress intensify factor for asphalt specimens can be predicted from this type of the statistical analysis.
In conclusion, this paper emphasises on the statistical and the experimental aspect of asphalt fracture mechanics that has investigated Weibull distribution model and the ability of this model to predict the important fracture parameters and the average stress intensify factor from a determined experimental data based on volumetric properties such as air voids. Finally, by investigating the errors for different models that suggested in this paper, indicatin the suitability of this model to predict the actual values of asphalt fracture.

Longitudinally seam welded pipes are frequently used in the oil and gas industries. Failure of such pipes may be occurred due to the crack growth initiated in the weld zone. At service conditions, cracks existing in these pipes usually experience complex tensile-shear deformations. For estimating the onset of fracture in the cracked pipes during their service life it is necessary to obtain the stress intensity factors. Hence in this paper, several 3D semi elliptical cracks initiated longitudinally along the weld line in the outer and inner wall of a welded pipe with different aspect ratios ranging from 0.5 to 1 are analyzed using ABAQUS software. It is shown that the contribution of all three modes (KI, KII and KIII) may affect significantly the onset of fracture in the investigated pipes. However, the effect of mode I deformation (KI) is more pronounced than the shear mode deformations (KII and KIII). It was also shown that the value of equivalent stress intensity factor in the inner wall is greater than the outer wall of cracked pipe.

Asphalt cracking is one of the major distress and deterioration modes of pavements of roads especially in the cold regions. Different types of cracks such as top-down، reflecting and alligator cracks are usually observed in the asphalt pavements. These cracks may be initiated due to improper construction and implementation of paving process، daily or seasonal cyclic thermal loads and mechanical traffic loading induced by moving vehicles. Consequently، the investigation of crack growth behavior in the asphalt overlays is an important issue for design، construction and maintenance of roads and highways. Due to the applied thermal and mechanical stresses، the cracks initiated in the asphalt layers may often experience different deformations including mode I (tensile or opening)، mode II (shear or sliding) and any combinations of opening-shearing deformations (i. e. mixed mode I/II). Fracture toughness is a key fundamental parameter for investigating the crack growth behavior of cracked bodies. From the other hand، since asphalt mixtures are composite materials composed of aggregate، binder and air void، their fracture behavior might be affected by the asphalt characteristics specifications. Hence in this research the influences of asphalt characteristic specifications (including the type and size of aggregates، bitumen type، air void content and the mixture composition) is investigated experimentally on the mixed mode fracture toughness of different asphalt mixtures. For conducting the fracture toughness experiments، semi circular bend (SCB) specimens containing a vertical edge crack and subjected to asymmetric three-point bend loading was used. In order to study the influence of mixture characteristic specifications on the value of fracture toughness، two aggregate types (i. e. limestone and siliceous)، two aggregate sizes (with nominal maximum aggregate sizes 19 mm and 4. 75 mm)، two binders (60/70 and 85/100) and two air void percentages (i. e. 4% and 6%) were considered for manufacturing asphalt mixtures. The SCB specimens were then tested under two different loading mode mixities (i. e. Me = 0. 8 (mixed mode condition with dominantly tensile deformation) and Me = 0. 38 (mixed mode condition with dominantly shear deformation) at -15oC. The load-displacement curves for the whole samples were linear which revealed the linear and elastic behavior of asphalt mixtures at the tested low temperature. Thus، the corresponding values of fracture toughness (KI، KII and Keff) were determined using the obtained fracture loads and the available formula. The experimental result showed that the mixed mode cracking resistance of asphalt mixtures is significantly affected by their properties. Analysis of results indicated that the specimens containing 4% air void (i. e. with the more compacted mixtures) show greater resistant against cracking than the asphalt specimens containing 6% air void. Meanwhile by increasing the maximum aggregate size the fracture toughness is also increased. Mixtures made of limestone aggregates and softer binders had more fracture toughness. Analysis of results also showed that when the contribution of mode II deformation is increased، the influence of air void and aggregate size on the fracture toughness of tested asphalt mixtures becomes negligible.

In the first part of this paper، the gas tungsten-arc welding process of a thin cylinder made of Al6061-T6 alloy is simulated using 3-D finite element model in the ABAQUS code and the distribution of residual stress is obtained. Temperature dependent thermo-mechanical properties are considered for the aluminum alloy and for simulating the heat source of tungsten arc welding، Goldak''s double ellipsoid model is also employed. Based on the finite element results، the value of residual stress is considerably positive around the weld line and HAZ area which can increase the risk of crack initiation and propagation in the weldment zone. Hence، in the second part of the numerical analyses of this research a longitudinal semi elliptical crack is considered in the wall of internally pressurized aluminum cylinder and its mode I stress intensity factor (KI) is determined numerically for different crack geometries. Finally the influence of both residual stress field and internal pressure is taken into account on the value of KI. It is observed that the effects of combined internal pressure and tensile residual stresses around the crack can facilitate required conditions for crack propagation in the analyzed cracked thin cylinder.