Failure Of Strips Research Articles

Experimental study on the flexural behaviors of ECC-reinforced masonry beams with GFRP mesh

This study aims to investigate the flexural behaviors of ECC-reinforced masonry beams with GFRP mesh under various interface treatment methods. Eleven sets of ECC-reinforced masonry beams with GFRP mesh were fabricated and subjected to a four-point bending test. The effects of the fibre volume fraction and thickness of ECC, interface treatment methods, GFRP mesh strength and layers on the flexural behavior of masonry beams were investigated and analyzed, including the failure mode, crack distribution, flexural strength, and load-deflection curves. The test results revealed that a transition in the failure mode of masonry beams from brittle failure to interfacial stripping failure or ductile failure after reinforcement. Increasing the number of GFRP mesh layers, the fibre volume fraction and thickness of ECC improved the flexural performance of the masonry beams, while increasing the GFRP mesh strength had the opposite effect. Among the variables, the interface treatment method exerted the greatest influence on the flexural performance of the masonry beams. The masonry beams treated with a bolt interface exhibited the best flexural performance, with flexural toughness and ultimate deflection increasing by 1.69 times and 0.32 times, respectively. Furthermore, the flexural performance of the masonry beams reinforced with a 15 mm thick ECC and single-layer GFRP mesh demonstrated similar reinforcement effects to the masonry beams reinforced with a 20 mm thick ECC, while reducing costs by 23 %. Based on the existing codes governing the calculation method of flexural strength and considering the influence of various factors, a calculation model for the flexural strength of ECC-reinforced masonry beams with GFRP mesh was established.

Experimental study on debonding and buckling of externally bonded carbon fiber reinforced polymer sheets in compression

Although the compressive strength of Fiber Reinforced Polymer (FRP) sheets is neglected in the design of FRP-retrofitted Reinforced Concrete (RC) elements, they may be subjected to compressive stress in some load combinations. In the present study, an experimental study is conducted to investigate the behavior of externally bonded Carbon Fiber Reinforced Polymer (CFRP) sheets in compression. The experimental program is carried out in two phases. First, the behavior of CFRP strips bonded on concrete cylinders and subjected to pure compressive load is assessed. At this stage, the influence of concrete compressive strength, the dimensions of CFRP strips (thickness, width, and free length), and the type of adhesive used for bonding CFRP strips on the concrete surface, on the behavior of CFRP strips in compression are investigated. According to the test results, the FRP strips bonded with weak resin exhibit debonding failure and simultaneously buckle at a relatively low compressive strain, while CFRP strips bonded with stronger adhesive do not exhibit debonding failure in compression until concrete crushing. The behavior of CFRP strips bonded on reinforced concrete (RC) beams subjected to compressive stress due to bending moment is investigated in the second phase of this study. For this purpose, nine RC beams with the same dimensions and reinforcement detailing are fabricated and retrofitted using CFRP strips with different configurations. Four-point bending test is conducted at this stage of the experimental program. The results of the bending tests show that debonding failure and buckling of CFRP strips are observed in specimens with relatively thick CFRP sheets (3 and 4-layer) and larger free lengths.

Study on simulation of cement plug—formation interface stripping failure and main influencing factors

Among the existing gas storage facilities, salt cavern gas storage has the advantages of high injection production efficiency, low gas cushion volume, safety, flexibility, etc. It is of great significance to speed up the construction of underground gas storage by transforming abandoned salt caverns of salt industry into underground gas storage. However, old salt cavern wells cannot be directly converted into gas storage injection and production wells, so the old wellbore must be plugged to ensure the effectiveness of plugging. Therefore, a set of plugging optimization technology for salt cavern gas storage wells is urgently needed. In this paper, a 3D finite element model of the cement plug-formation system based on cohesive element method is established for the milling and plugging of the old well in the salt cavern gas storage section. The results show that under the condition of constant gas storage pressure, a certain degree of small deformation will occur at the bottom of the cement plug after compression, resulting in the shear direction deformation of the cement plug formation cementation interface, and peeling will occur after accumulation to a certain extent. With the increase of simulation time, the length of stripping section gradually increases and tends to be stable, and reaches the limit of stripping failure length. In the process of research, the factors and laws affecting the stripping failure length were also analyzed. It was found that the stripping failure length of cement plug formation cementation interface was related to the maximum operating pressure of gas storage, cement plug length, cement plug diameter, elastic modulus, Poisson’s ratio and other factors. The research results are helpful to judge whether the milling and plugging length of the old well section is sufficient, and provide theoretical guidance for ensuring the long-term safe operation of the gas storage.

Experimental studies on confined compressive strength of Stainless Steel Wire Mesh (SSWM) wrapped concrete columns

The findings of an experimental evaluation of the axial compressive strength of an M25 grade Plain Cement Concrete (PCC) column confined with locally available Stainless Steel Wire Mesh (SSWM) are presented in this paper. Various types of Fiber Reinforced Polymer (FRP) are usually employed to strengthen the load-bearing components of concrete structures. However, these FRP materials exhibits brittle failure and debonding of FRP strip or wrap. Stainless Steel Wire Mesh (SSWM), on the other hand, is a cost-effective substitute for FRP materials when it comes to strengthening of structural elements. In this study, effectiveness of SSWM for confinement of concrete columns is demonstrated through experimental study. For the research, column specimens with a diameter of 150 mm and a height of 300 mm are used. Test specimens are strengthened with one-layer circumferential wrap of SSWM. Three variants of SSWM i.e. SSWM 30 × 32, SSWM 40 × 32 and SSWM 50 × 34 are considered for the study. After 28 days of moist curing, SSWM is applied to the column surface using epoxy SIKADUR 30LP. Axial compressive load-carrying capacities of strengthened specimen are compared with that of control specimens. From the comparative study it is found that SSWM 40 × 32 performs better compared to other variants of SSWM considered for this study. Compared to the control specimen, the load-carrying capacity of the column strengthened with SSWM 40 × 32 is increased by 29.35%. For all the specimen, failure patterns are observed in addition to the load–displacement and stress–strain behaviour. Results of present experimental investigation establishes the suitability of SSWM for confinement or strengthening of concrete elements subjected to compression.

Investigation Moisture Content Effect on Bearing Capacity Failure of Strip Footing Rested on Silty Sand Soil Based on Crack Characteristics Assessment Using Non-Destructive Test

Investigation Moisture Content Effect on Bearing Capacity Failure of Strip Footing Rested on Silty Sand Soil Based on Crack Characteristics Assessment Using Non-Destructive Test

Dynamic failure of composite strips under reverse ballistic impact

Mesoscale impact experiments on composite strips were conducted in this study to reveal the fundamental failure mechanisms of fiber-reinforced composites (FRCs) under transverse impact by different projectiles. The componential material of composite armor, S-2 glass/SC-15, was manufactured into a single ply and sectioned into strips. The strip specimens were first characterized by X-ray computed tomography and scanning electron microscopy (SEM). The impact experiments were performed using a light-gas gun, shooting the strip specimens to the static wedge-nose projectiles with different nose diameters of 4, 40, and 400 µm. A high-speed camera recorded the strip's failure process from the side. Such a reverse ballistic impact scheme enabled to focus the camera on the projectile nose where the strip was deformed and fractured so that the entire failure process was recorded in real time. These experiments identified three failure modes of the composite strip for each projectile type, defined by no, partial, and complete local failure by the impact loading. The critical velocity region was quantified, showing rising upper and lower boundaries corresponding to the projectile nose diameter. The experimental data were compared with theoretical predictions by Smith's theory. The transverse wave speed deviated from Smith's prediction as the projectile nose diameter decreased, demonstrating a possibly significant error when the pure-tension assumption is employed to model the composite's impact behavior by sharper projectiles. Besides, a sharper projectile was more likely to induce a smaller tent angle, indicating a larger local deformation, considered owing to the stress concentration at the projectile nose.

Bolt stripping failure and ductility of end plate beam-column connections at ambient and elevated temperatures

PurposeThe effect of bolt stripping failure on the ductility of steel end plate beam-column connections has received relatively little investigation to date. The objective with the present work is to establish a validated numerical model of end plate connections at elevated temperatures, which predicts the mechanical behaviour and failure modes observed in the experimental tests including the bolt stripping failure. Furthermore, the validated FE model was used to investigate the effect of stripping failure on both the rotational and load-bearing capacity of end plate connection.Design/methodology/approachThe analysis was conducted on a validated numerical model of end plate connections at elevated temperatures, which predicts the mechanical behaviour and failure modes observed in the experimental tests including the bolt stripping failure. The material was modelled considering ductile damage initiation and evolution featured in ABAQUS/Standard.FindingsThis study demonstrates that thick end plates can prevent stripping failure which significantly improves the rotational capacity of the connection. This failure mode can develop readily with thin end plates; however the effect is often unrealistically mitigated through idealised experimental tests. The rotational capacity of a connection can be 5.0 times higher if stripping failure is avoided, particularly at elevated temperatures. Eurocode 3 part 1.8 does not consider the possibility of stripping failure when discussing the requirements for plastic analysis. It is concluded in the present study that by allowing for the possibility of bolt stripping, the mode of failure can often shift from end plate failure to bolt stripping, this in turn significantly reduces the connection rotational capacity.Originality/valueThe effect of bolt stripping failure on the ductility of steel end plate beam-column connections has received relatively little investigation to date.

Ultralong Lifespan for High-Voltage LiCoO2 Enabled by In Situ Reconstruction of an Atomic Layer Deposition Coating Layer

Although the rapid development of electrical energy storage devices has slowed down environmental pollution, their large-scale application has posed huge challenges to battery-related mineral resources; thus, extending the lifespan of high-voltage lithium cobalt oxide (LCO) is of great importance. Surface oxide coating is considered as the most common low-cost modification method for addressing unstable cycling performance. However, studies have shown that the oxide layer would further react with an electrolyte, while the investigation on the corresponding component evolution is lacking. Herein, a typical example utilizing the above reaction to realize surface reconstruction is presented. Applying atomic layer deposition (ALD), originally, an ultrathin Al2O3 layer is coated on the LCO surface; however, this coating layer has undergone reconstruction after reacting with electrolyte decomposition products during the cycling. Compared with simple coating, the in situ formed Li3AlF6 layer has a tighter binding to the LCO surface while possessing good Li+ conductivity and electrochemical stability. In addition, the unique properties of the ALD technology allow us to achieve ultrathin (1 nm) and conformal coating, which is beneficial for electronic conductivity and cycling stability. Furthermore, the surface phase transition layer stripping failure mechanism has first been revealed to explain the loss of Co and O, while the reconstructed Li3AlF6 effectively suppresses the surface stripping. Thus, excellent high-voltage performance has been realized (an 89% capacity retention after 1000 cycles at 4.5 V and an 88% capacity retention after 200 cycles at 4.6 V). This work casts a new understanding on the surface reconstruction of the oxide coating layer, which is also significant for other electrode materials' modification.

Bending Performance of Epoxy Adhesive Joints of Prefabricated Concrete Elements

The assembly construction of prefabricated UHPC elements can well balance quality reliability and construction convenience, thus it has excellent application prospects in bridge engineering. The joints between prefabricated elements are the key to ensuring the overall force performance of the structure, which directly determine the load-bearing capacity and the life of structure. To clarify the bending behavior of epoxy adhesive joints between prefabricated UHPC elements, four groups of 12 bending tests were carried out with different interface treatment forms as parameters. The failure modes, load-deflection curves, and ultimate bending strength of the interface were investigated. The results reveal that the interfacial failure modes mainly include the interfacial stripping failure of epoxy-UHPC surface, steel fibers and fine aggregates into UHPC surface by pulling out, and tensile damage of UHPC at the root of key teeth on the side of the keyway interface. The load-deflection curves of all specimens exhibit the two-fold lines form. The load tends to rise linearly during the loading phase, and there is no yielding phase before the failure. The load-carrying capacity of the specimen is lost immediately after the failure, and no reliable residual strength is available except for the keyway interface. In addition, the bending strength of rough interface, groove interface, and keyway interface are respectively improved by −24.02, 2.34, and 4.64%, compared with the natural interface. So it is recommended that the joint between prefabricated UHPC elements take the form of keyway interface. Finally, a simplified force model of the keytooth adhesive joint is proposed, and a calculation formula for the flexural bearing capacity is established based on the principal of Mohr’s circle, based on the experimental results and theoretical analysis. The mean ratio of the proposed adhesive joint calculation equation to the experimental results was 0.925 with a standard deviation of 0.065.

Analysis of the Reasons for the Tearing of Strips of High-Strength Electrical Steels in Tandem Cold Rolling.

High-strength non-oriented electro-technical steels with a low thickness possess excellent isotropy of electromagnetic and mechanical properties which is highly required in the production of high-efficiency electric motors. The manufacturing process of this type of steel includes very important and technologically complex routes such as hot rolling, cold rolling, temper rolling, or final heat treatment. The final thickness is responsible for the decrease in eddy-current losses and is effectively achieved during cold rolling by the tandem rolling mill. Industrial production of thin sheets of high-strength silicon steels in high-speed tandem rolling mills is a rather demanding technological operation due to the increased material brittleness that is mainly caused by the intensive solid solution and deformation strengthening processes, making the dislocation motion more complex. The main objective of this work was to investigate the distribution of local mechanical strains through the thickness of high silicon steel hot bands, generated during the cold rolling. The experimental samples were analysed by means of electron back-scattered diffraction and scanning electron microscopy. From the performed analyses, the correlation between the material workability and the nucleation of cracks causing the observed steel strip failure during the tandem cold rolling was characterized. Specifically, the microstructural, textural, misorientation, and fractographic analyses clearly show that the investigated hot band was characterized by a bimodal distribution of ferrite grains and the formation of intergranular cracks took place only between the grains with recrystallized and deformed structures.

Pantograph Sliding Strips Failure-Reliability Assessment and Damage Reduction Method Based on Decision Tree Model.

Damage to the pantograph or sliding strip may cause the blocking of the railway line. This is the main reason for which the prediction of pantographs’ failure is important for railway carriers and researchers. This article presents a sliding strips failure prediction method as a main means of preventing disruptions to the transport chain. To develop the best predictive model based on the decision tree, the complex tree, medium tree and simple tree machine learning methods were tested. Using a decision tree, the categorization of the given technical conditions can be properly realized. The obtained results showed that the presented model can reduce sliding strip failure by up to 50%. Special attention was paid to the current collector (AKP-4E, 5ZL type), measured during periodic reviews of locomotives EU07 and EU09. To assess the reliability of the selected pantograph strips, a non-destructive degradation analysis was carried out. On the basis of the wear measurements of the strips and the critical value of wear, a failure distribution model was developed. Operational data, collected during periodic technical reviews, were provided by one of the biggest railway carriers in Poland. The results of the performed analyses may be used to build a preventive maintenance strategy to protect pantographs. The applied reliability models of wear propagation can be extended by the parameters of the cost and repair time becoming the basis for estimating the costs of operation and maintenance.

Selecting Suitable Bolt Parameters to Achieve Ductility at Elevated Temperatures

AbstractA detailed FE study is presented investigating the factors affecting failure modes of bolt assemblies under tensile force at ambient and elevated temperatures. Axisymmetric FE models incorporating important behavioural aspects including surface interaction and damage modelling were developed. Stripping failure is generally undesirable because it results in premature failure of the bolt, which can deteriorate the rotational capacity of connections and robustness of steel frames. The paper discusses how the thread length in the grip Lt can affect the failure mode of bolt assemblies at elevated temperatures. This paper concludes that at ambient temperature, stripping can occur at certain Lt length dependent upon the nut dimension deviation from the basic profile; this length reduces with temperature.

Fracture simulation of fully and partially threaded bolts under tension

AbstractThe tensile behaviour of bolts has direct effects on the performances of structural bolted joints. Conventional studies mainly focus on the stiffness and strength of bolt assemblies, whereas the deformation and fracture behaviour of fully and partially threaded bolts under tension is rarely investigated. This paper presents a numerical investigation of the fracture behaviour of fully and partially threaded bolts based on the experimental results in literature [5]. Firstly, a combined linear and power stress‐strain relation is used to describe the post‐necking stress‐strain relations of fully and partially threaded bolts. Direct tension tests on fully and partially threaded bolts are modelled using ABAQUS with the explicit solver. The fracture criterion proposed by Bao and Wierzbicki [10] is used to simulate the bolt tensile fracture and thread stripping failure. Numerical results indicate that the large deformation behaviour and the failure mode of fully and partially threaded bolts under tension could be accurately predicted combining the calibrated post‐necking stress‐strain relations and the Bao‐Wierzbicki fracture criterion with suitable parameters.

Impacts of Maltene on the Wettability and Adhesion Properties of Rejuvenated Asphalt Binder

In recent years, the use of reclaimed asphalt pavement (RAP) has gained much attention and is widely accepted. However, the rejuvenating agents which are usually used to reduce the rigidity of the aged asphalt are subjected to diverse climate circumstances. The present work used maltene as a rejuvenator to investigate several measurements regarding stripping failure. The evaluation of wettability and work of adhesion (WA) was assessed using the sessile drop method. Meanwhile, asphalt and asphalt-water aggregate systems were tested for acid and water resistance using chemical and water immersion tests. Next, atomic force microscopy (AFM) was used to evaluate the changes in the microstructures of the asphalt binders. The experimental results revealed that the ideal percentages of maltene which should be added to 30% and 50% aged asphalt were 8% and 16%, respectively. Meanwhile, the wettability, WA and resistance to stripping differed depending on the percentage of aged asphalt in the blend. However, the inclusion of maltene has improved samples containing high percentages of aged asphalt. On the other hand, the resistance to boiling water containing acid decreased slightly with the addition of maltene. Nevertheless, all the rejuvenated samples exhibited better results than virgin asphalt. Moreover, the AFM results were in line with the observations, suggesting the suitability of maltene for the functional application of pavement.

Optimization of kenaf fibre reinforced polymer laminate for shear strengthening of RC beams using embedded connector

Kenaf fibre reinforced polymer (KFRP) laminate has gained its potentiality in shear strengthening of reinforced concrete beams recently, thus, method to obtain the minimal required dimension of KFRP shear strip is the utmost demand. The main aim of this research was to optimize the dimension of KFRP laminate for shear strengthening of RC beam. In experimental programme, high strength KFRP laminate and seven full scale RC beams were fabricated. The beams were shear strengthened using 7.5 mm thick and 20 mm, 30 mm and 35 mm widths of KFRP laminate, the dimensions of those shear strips were based on design strains of 0.007, 0.0045 and 0.004 respectively. Beams were also shear strengthened using CFRP laminates with similar widths of KFRP laminates for comparison. All beams were numerically analysed. Parametric study on design strain based on theoretical model was also conducted. Results showed that shear strengthened beam with 0.007 strain of KFRP laminate failed due to fracture of laminate. However, beams with laminate strains of 0.0045 and 0.004 did not show fracture or debonding of KFRP laminates, both beams had shown ductile flexural mode of failures with higher failure loads. In contrast, all CFRP laminate strengthened beams failed because of cover separation of laminates followed by shear. The failure loads of KFRP laminates strengthened beams were found to be higher as compared to those of CFRP laminates. The KFRP laminates were effectively enhanced shear capacity of strengthened beams without showing any premature failure even with the design strain of 0.0045, while, CFRP laminate showed premature cover separation failure with design strain of 0.002. Theoretical model showed that higher strength of concrete and length of laminate increased debonding or design strain of laminate. The numerical model predicted flexural and shear behaviour of shear strengthened beams. The flexural behaviour of strengthened beams based on numerical analysis were closely comparable with those of experimental findings. However, the model had limitation to predict local debonding failure of shear strip due to cracks and the effects of debonding on shear behaviour of strengthened beams.

Fracture simulation of partially threaded bolts under tensile loading

Failure of bolts exposed to tension is generally avoided in the design of bolted connections due to the smaller deformation capacity of bolts than the connected plates. This is one of the reasons why few studies focus on the tensile failure behaviour of bolts. However, failure behaviour of bolts is essential for the advanced finite element analysis especially relevant to the deformation capacity and failure mode of bolted connections. This paper presents a numerical study on the fracture of partially threaded bolts under tension incorporating damage models, with which the failure mechanism of bolts can be better understood. The post-necking stress–strain relation is firstly calibrated to describe the behaviour of bolt threaded parts at large deformation. Then, direct tension tests on partially threaded bolts with different threaded lengths within the grip are modelled using ABAQUS with the explicit solver. Two criteria for fracture are investigated: the void growth model (VGM) and a model proposed by Bao and Wierzbicki (BW). The former is adopted to simulate the tensile fracture of bolts and the latter is used to predict the thread stripping failure. Results indicate that bolt failure modes of tensile fracture and thread stripping can be well predicted by combining the calibrated post-necking stress–strain relation and a suitable fracture criterion in the analysis. It is revealed that the large plastic strain in the threads introduced by thread rolling process is a major reason for the thread stripping failure.

A numerical investigation into stripping failure of bolt assemblies at elevated temperatures

A detailed finite element (FE) study is presented investigating the factors affecting the failure modes of high strength and stainless steel bolt assemblies under tensile force at ambient and elevated temperatures. Axisymmetric FE models incorporating key behavioural aspects including surface interaction and damage modelling of steel at elevated temperatures were developed. In practice, stripping failure is generally undesired because it results in premature failure of the bolt which can deteriorate rotational capacity of connections and hence compromise the robustness of steel frames. Yet, stripping failure has not been previously investigated in the open literature. In this study, the examined stainless steel bolt assemblies displayed an outstanding ductile response even when stripping failure was observed. Parameters that can govern the failure modes of bolt assemblies at elevated temperatures include the thread length in the grip (Lt), and the relative strength and friction between the mating threads. At ambient temperature, stripping was observed at certain Lt lengths depending on the nut dimension deviation from the basic profile. The Lt stripping failure threshold reduces with temperature for high strength bolt assemblies while the value fluctuates without a discernible pattern for stainless steel types. Increasing the relative strength and friction coefficient can reduce the Lt length threshold, with the former having the greatest influence. It was also found that larger bolt sizes are more vulnerable to thread stripping failure.

Experimental study on high pre-cracked RC beams shear-strengthened with CFRP strips

Experimental studies on shear capacity of eighteen pre-cracked reinforced concrete (RC) beams shear-strengthened with carbon fiber reinforced polymer (CFRP) strips are carried out in this study. The effects of CFRP strips spacing, shear span ratio and pre-cracked degree on the failure mode, shear capacity, load-deflection curve and moment-curvature relationship of strengthened specimens are analyzed. Three failure modes related to the failure of CFRP strips, that is the bonding failure, the debond failure and the fracture failure of CFRP strips, are observed for specimens with different structural parameters. Moreover, with decrease of CFRP strips spacing, the shear capacity, the ultimate deflection and the bending stiffness of specimens increase. With increase of pre-cracked degree, the increment of shear capacity of RC beams shear-strengthened with CFRP strips is lower than that of non-cracked beams. The pre-cracked degree presents slight effect on the stiffness of CFRP strips-strengthened beams. Further, a revised model to determine the shear capacity of CFRP strips is proposed by accounting for the strain distribution of CFRP strips and the pre-cracked degree. Comparison between the experimental results and the calculated values indicates that the proposed formula can versatilely evaluate the shear capacity of CFRP strips strengthened RC beams.

Assessment of aggregate-bitumen coverage using entropy-based image segmentation

Adhesion between bitumen and aggregates has a major impact on the performance of asphalt mixes. In order to avoid stripping and consequent premature failure of a pavement, methods to assess the adhesion have been developed and standardised. These methods, such as the frequently applied rolling bottle test defined in EN 1269-11, are based on visual inspection of specimens and subjective evaluation. This shortcoming can be eliminated by employing image analysis that accurately and consistently identifies the portion of aggregate covered by bitumen. However, the image segmentation procedure cannot be based purely on intensity thresholding because the light reflections on the glossy surface of bitumen merge together with light aggregates, and dark aggregates coincide with diffuse bitumen reflections. In this article, a method based on local entropy calculation is proposed to tackle this issue in the form of an open-source software tool. Its algorithms are thoroughly described here, and their impact is illustrated using a model example. Software outcomes are compared with an advanced, yet more complicated, approach. How the software might be used in other fields is also outlined and discussed.

Чистий згин полоси (балки) з довільно орієнтованою наскрізною тріщиною

The problem of pure bending of strip (beam) with transverse rectilinear crack, edges of which are free from acuter load, is investigated in this paper. Under bending moment its edges may not contact or smoothly contact throughout its area length or part. Dependently on where it is located.Using methods of theory of functions of complex variable and complex potentials the problem at issue has been reduced to the problems of linear conjugation, their analytical solution is found. Explicit expressions on complex potentials is written. Based on the energy criterion of destruction stress intensity factors are determined. Limit value of moment when the crack begins to propagate is found. For the case when crack edges partially contact, area length of contact of her edges is determined. Numerical analysis of critical moment of failure of strip (beams) is performed under various parameters of the problem, which are related to the mechanical state of crack. The corresponding graphic dependencies are constructed.