Deepest Point Research Articles

Three-dimensional reconstruction study of the displacement of undisplaced femoral neck fractures

To measure the displacement parameters of femoral head in space through three-dimensional reconstruction so as to reunderstand undisplaced femoral neck fractures. The clinical data of 80 undisplaced femoral neck fractures from January 2010 to June 2011 were selected, included Garden I 40 cases (group Garden I) and Garden II 40 cases (group Garden II), bilateral proximal femurs of everyone were scanned by CT and reconstructed by professional software. Registered the normal femur and fracture with mirror model, marked key points in the model and measured the displacement parameters of femoral head. The measurement accuracy of distance and angle were 0.01 mm and 0.01°, respectively. The parameters of femoral head displacement between group Garden I and Garden II were analyzed by independent-sample t-test. Eighty cases on X-ray films were not found rotated displacement. But 24 cases of them (30.0%) showed rotated displacement and rotation direction of the femoral head through three-dimensional reconstruction. Ten cases showed incomplete fractures on X-ray films, but only 3 cases were incomplete fractures with three-dimensional reconstruction. In group Garden I, the femoral head displacement angle was 18° ± 11°, the average displacement distance of femoral head center and deepest point of fovea capitis were (6 ± 3) mm and (10 ± 6) mm respectively. In group Garden II, the femoral head displacement angle was 17° ± 10°, the average displacement distance of femoral head center and deepest point of fovea capitis were (7 ± 5) mm and (13 ± 8) mm respectively. There were not statistical significance of the parameters of femoral head displacement between group Garden I and Garden II (P > 0.05). Three-dimensional reconstruction and digital measurement is a precise, efficient method for the measurement of femoral head displacement parameters in femoral neck fractures, has important clinical significance in the diagnosis and treatment of the femoral neck fractures. There are certain defects and limitations of the classical Garden classification for undisplaced femoral neck fractures.

The Hadal Amphipod Hirondellea gigas Possessing a Unique Cellulase for Digesting Wooden Debris Buried in the Deepest Seafloor

The Challenger Deep in the Mariana Trench is the deepest point in the ocean (10,994 m). Certain deep-sea animals can withstand the extreme pressure at this great depth. The amphipod Hirondellea gigas is a resident of the Challenger Deep. Amphipods are common inhabitants at great depths and serve as scavengers. However, there is relatively little information available regarding the physiology of H. gigas or this organism's ecological interactions in the hadopelagic zone. To understand the feeding behavior of this scavenger in the deepest oligotrophic hadal zone, we analyzed the digestive enzymes in whole-body extracts. We describe the detection of amylase, cellulase, mannanase, xylanase, and α-glycosidase activities that are capable of digesting plant-derived polysaccharides. Our identification of glucose, maltose, and cellobiose in the H. gigas extracts indicated that these enzymes function under great pressure in situ. In fact, the glucose content of H. gigas averaged 0.4% (w/dry-w). The purified H. gigas cellulase (HGcel) converted cellulose to glucose and cellobiose at an exceptional molar ratio of 2∶1 and efficiently produced glucose from dried wood, a natural cellulosic biomass, at 35°C. The enzyme activity increased under a high hydrostatic pressure of 100 MPa at 2°C, conditions equivalent to those found in the Challenger Deep. An analysis of the amino acid sequence of HGcel supported its classification as a family 31 glycosyl hydrolase. However, none of the enzymes of this family had previously been shown to possess cellulase activity. These results strongly suggested that H. gigas adapted to its extreme oligotrophic hadal oceanic environment by evolving digestive enzymes capable of digesting sunken wooden debris.

Papers in This Issue

fatigue category E in the unreinforced configuration to the infinite fatigue life range. Test results also showed that the fatigue strength of the bond layer was drastically improved by introducing breather cloth material within the bond layer. The paper “Advanced Numerical Modeling of Cracked Tubular K-Joints: BEM and FEM Comparison” by Borges et al. investigates a critical aspect in the design of tubular bridges: the fatigue performance of the structural joints. The estimation of a fatigue-crack life using the linear elastic fracture mechanics (LEFM) theory involves the calculation of stress intensity factors (SIF) at a number of discrete crack depths. The most direct way is to carry out modeling by either the finite-element method (FEM) or the boundary-element method (BEM). For tubular joints commonly found in tubular bridges and off-shore structures, because of the complicated geometry resulting from the tubes’ intersection and welding, the construction of the numerical model often becomes a complex process. This paper presents two different model-construction techniques that have been developed independently at the Swiss Federal Institute of Technology (EPFL) and the Nanyang Technological University (NTU), Singapore, which are based on the BEM and the FEM, respectively. The SIF values obtained by these two methods are compared. It is found that so long as consistent geometrical models are employed, compatible SIF values could be obtained by both approaches. The best and the most consistent values are obtained for the deepest point along the crack front. These values should be used for fatigue-life computations. In the paper “Fatigue Reliability Assess

Conservation Concerns in the Deep

In their Perspective “A dive to challenger deep” (20 April, p. [301][1]), R. A. Lutz and P. G. Falkowski highlight the exciting advancements in engineering that allowed director James Cameron to dive to Challenger Deep, the deepest point on Earth. As Lutz and Falkowski point out, ever-improving

Three-dimensional reconstruction study of the displacement of impacted femoral neck fractures

Objective To measure the displacement parameters of the femoral head in space through CT three-dimensional reconstruction so as to re-understand impacted femoral neck fractures.Methods Fifty patients with impacted femoral neck fractures were included in the study.There were 17 males and 33 females.Bilateral proximal femurs of each patient were scanned by spiral CT preoperatively.Then these primitive CT data were reconstructed by Mimics 10.01 software.Registered the normal femur and fracture mirror model,the registered mirror model was generated a new mask in the CT cross-sectional images,marked key points in the masks and measured the displacement parameters of femoral head with three-dimensional measurement technology.Results In the impacted femoral neck fractures,the femoral head displacement angle was 17.17°±10.40°,70％ (35/50) of the patients had femoral head rotation angle was at 10° to 35°,and 30％(15/50) of the patients had femoral head space displacement more than 20°.The average displacement distance of femoral head center and the deepest point of fovea capitis were (6.49±3.60) mm and (10.42±5.92) mm,respectively.A high proportion of the impacted femoral neck fractures had a large of displacement in the three-dimensional space.It is not scientific to equal impacted femoral neck fractures to undisplaced fractures.Conclusion Three-dimensional reconstruction and digital measurement is a precise,efficient and convenient method for the measurement of femoral head displacement parameters in femoral neck fracture patients.The classic Garden classification for impacted femoral neck fractures has certain defects and limitations.Clinicians should re-understand impacted femoral neck fractures and choose more reasonable treatment. Key words: Femoral neck fractures; Imaging, three-dimensional; Classification

Bathymetry and Sediment Geochemistry of Lake Hazen (Quttinirpaaq National Park, Ellesmere Island, Nunavut)

Arctic lakes can provide a long-term perspective on environmental change, including trends in long-range atmospheric transport and deposition of contaminants, inferred from studies of sediment cores. In this study, we conducted the first detailed bathymetric survey of Lake Hazen (Quttinirpaaq National Park, Ellesmere Island, Nunavut), the world’s largest lake north of 74˚ latitude. With these data we were able to determine optimal locations for sediment coring and to collect and analyze profundal sediment cores. A bathymetric map of Lake Hazen was developed on the basis of 362 spot soundings obtained with GPS-coupled sounding equipment placed directly on the ice combined with additional soundings from a small boat. The deepest point in the lake (81˚49.5 ʹ N; 70˚42.8 ʹ W) was found to be 267 m deep. The lake volume was estimated to be 5.14 × 10 10 m 3 , about 10% larger than previous estimates. Using estimates of the discharge of Lake Hazen from the Water Survey of Canada, we estimated the water retention time to be 89 years. Sediment cores were dated using 210 Pb and 137 Cs. Sedimentation rates at the deep point, estimated using the Constant Rate of Supply model for excess 210 Pb, were relatively high (1260 g m -2 yr -1 ) in the period 2005 – 1963 and lower (650 ± 100 g m -2 yr -1 ) in horizons dated to 1950 – 1880. The majority of elements measured in sediment (24 of 29 consistently above detection limits), as well as organic carbon, showed less than 20% variation in concentrations in the top 10 cm (compacted depth), which represent deposition over approximately 140 years. Geochemical characteristics of the sediment suggest that erosional inputs from annual glacial melting are the major source of essentially all elements and that anthropogenic inputs from long-range transport of toxic metals such as mercury and lead are very low.

A Residual Stress Intensity Factor Solution for Knoop Indentation Cracks

The residual stress intensity factors at the surface and at the deepest point of the semi-elliptical Knoop indentation crack is determined from the stresses in the damaged zone below the indenter. For this purpose, the weight function approach by Cruse and Besuner was used and wide-range expressions of the geometric function are given. The solution is then applied to a commercial silicon nitride for which all relevant geometrical data are available.

Gravity inversion of 2D bedrock topography for heterogeneous sedimentary basins based on line integral and maximum difference reduction methods

ABSTRACTBased on the line integral (LI) and maximum difference reduction (MDR) methods, an automated iterative forward modelling scheme (LI‐MDR algorithm) is developed for the inversion of 2D bedrock topography from a gravity anomaly profile for heterogeneous sedimentary basins. The unknown basin topography can be smooth as for intracratonic basins or discontinuous as for rift and strike‐slip basins. In case studies using synthetic data, the new algorithm can invert the sedimentary basins bedrock depth within a mean accuracy better than 5% when the gravity anomaly data have an accuracy of better than 0.5 mGal. The main characteristics of the inversion algorithm include: (1) the density contrast of sedimentary basins can be constant or vary horizontally and/or vertically in a very broad but a priori known manner; (2) three inputs are required: the measured gravity anomaly, accuracy level and the density contrast function, (3) the simplification that each gravity station has only one bedrock depth leads to an approach to perform rapid inversions using the forward modelling calculated by LI. The inversion process stops when the residual anomalies (the observed minus the calculated) falls within an ‘error envelope’ whose amplitude is the input accuracy level. The inversion algorithm offers in many cases the possibility of performing an agile 2D gravity inversion on basins with heterogeneous sediments. Both smooth and discontinuous bedrock topography with steep spatial gradients can be well recovered. Limitations include: (1) for each station position, there is only one corresponding point vertically down at the basement; and (2) the largest error in inverting bedrock topography occurs at the deepest points.

The macrosemiiform fish companion of the Late Jurassic theropod Juravenator from Schamhaupten, Bavaria, Germany

A new neopterygian fish, Voelklichthys comitatus n. gen. n. sp., is described. The fish was found during the preparation of the theropod Juravenator starki Göhlich & Chiappe, 2006 in the same rock. The fish possesses numerous autapomorphies. The combination of autapomorphies is unique among Jurassic fishes and makes its taxonomic assignment difficult. The following characters are few examples demonstrating some of the peculiarities of the fish: The fish is small, oblong-shaped and has a large triangular head that is deeper than long; deepest point is at the level of the postparietal bone [parietal of traditional terminology] and the ventral end of the cleithrum. The skull roof is almost vertically oriented, with a strongly ossified and developed antero-dorsal orbital margin. Premaxilla and dentary possess very small conical teeth. The opercular apparatus is markedly narrow and deep. A clavicle is present. Both dorsal and ventral postcleithra are almost as deep as the maximum depth of the head; the dorsal postcleithrum is two times deeper than the ventral one. The vertebral centra are of arcocentral-type formed mainly by the development of the dorsal arcocentra. Pectoral and pelvic fins possess long rays that extend onto the pelvic and anal fins, respectively, whereas the rays of the dorsal and anal fins extend onto the caudal fin. The fish is interpreted as a macrosemiiform because it presents two of the three synapomorphies of the group (e.g., an incomplete circumorbital ring because the lateral edge of parietal bone [frontal of traditional terminology] makes up part of orbital margin and absence of a supramaxillary bone). The third macrosemiiform synapomorphy cannot be determined in the new fish because the coronoid bones and their dentition are not observed due to condition of preservation. The new fish shares a few characters with members of the families Macrosemiidae and the Uarbryichthyidae but lacks others so that presently, we place it in a family indeterminate within Macrosemiiformes. doi:10.1002/mmng.201200001

Brittle Crack Propagation/Arrest Behavior in T-Joint Structure of Heavy Gauge Steel Plates

Brittle crack arrestability is extremely important in welded joints of heavy gauge steel plates used in large container ships. Recently, much attention has been focused on potential crack propagation along welds using large heat input. This paper examines the application of a T-joint to the strength deck structure of container ships to enhance crack arrestability. The crack arrest toughness, Kca, for crack arrest was varied. The ESSO test of T-joint components showed that brittle crack was arrested at the T-joint if the steel plate used for the flange had a high Kca value in the range from 4900 to 7300N/mm3/2. FE-analysis of the stress intensity factor K indicated that brittle crack propagation was arrested under the condition that the K-value at the running crack tip was less than the Kca of the material. In the T-joint, it was noted that the K-value around the area of the deepest point of the crack decreased and was finally less than the Kca of the flange plate when the brittle crack penetrated suddenly into the flange plate to a 10mm depth. This phenomenon shows the advantage of using a T-joint for brittle crack arrest in the flange plates of strength deck structures.

The macrosemiiform fish companion of the Late Jurassic theropod <i>Juravenator</i> from Schamhaupten, Bavaria, Germany

A new neopterygian fish, <i>Voelklichthys comitatus</i> n. gen. n. sp., is described. The fish was found during the preparation of the theropod <i>Juravenator starki</i> Göhlich & Chiappe, 2006 in the same rock. The fish possesses numerous autapomorphies. The combination of autapomorphies is unique among Jurassic fishes and makes its taxonomic assignment difficult. The following characters are few examples demonstrating some of the peculiarities of the fish: The fish is small, oblong-shaped and has a large triangular head that is deeper than long; deepest point is at the level of the postparietal bone [parietal of traditional terminology] and the ventral end of the cleithrum. The skull roof is almost vertically oriented, with a strongly ossified and developed antero-dorsal orbital margin. Premaxilla and dentary possess very small conical teeth. The opercular apparatus is markedly narrow and deep. A clavicle is present. Both dorsal and ventral postcleithra are almost as deep as the maximum depth of the head; the dorsal postcleithrum is two times deeper than the ventral one. The vertebral centra are of arcocentral-type formed mainly by the development of the dorsal arcocentra. Pectoral and pelvic fins possess long rays that extend onto the pelvic and anal fins, respectively, whereas the rays of the dorsal and anal fins extend onto the caudal fin. The fish is interpreted as a macrosemiiform because it presents two of the three synapomorphies of the group (e.g., an incomplete circumorbital ring because the lateral edge of parietal bone [frontal of traditional terminology] makes up part of orbital margin and absence of a supramaxillary bone). The third macrosemiiform synapomorphy cannot be determined in the new fish because the coronoid bones and their dentition are not observed due to condition of preservation. The new fish shares a few characters with members of the families Macrosemiidae and the Uarbryichthyidae but lacks others so that presently, we place it in a family indeterminate within Macrosemiiformes. <br><br> doi:<a href="http://dx.doi.org/10.1002/mmng.201200001" target="_blank">10.1002/mmng.201200001</a>

Detection of periodontal bone loss using cone beam CT and intraoral radiography

The aim of this study was to compare periapical radiographs with cone beam CT (CBCT) imaging in detecting and localizing alveolar bone loss by comparing linear measurements of the height, depth and width of the defects and identifying combined bone defects in tomographic images. The images were selected from a secondary database containing images of patients referred for periodontal evaluation. The sample consisted of 51 sites showing both horizontal and vertical bone loss, assessed by 3 trained examiners. The results showed that there were no statistically significant differences between the imaging methods in terms of identification of the pattern of bone loss. However, there were differences between the two methods when the distance between the cemento-enamel junction (CEJ) and the alveolar crest (AC) was measured. When the distance between the CEJ and the deepest point and width of the defect were measured, the methods showed no statistically significant difference. In this study, 30.8% of the 39 teeth evaluated had combined bone defects. The two methods differ when detecting the height of the alveolar bone crest but present similar views of the depth and width of bone defects. CBCT was the only method that allowed for an analysis of the buccal and lingual/palatal surfaces and an improved visualization of the morphology of the defect.

Frontal sinus depth at four landmarks in breeds of dog typically affected by sinonasal aspergillosis

The objective of this study was to assess whether the frontal sinuses in dogs with aspergillosis and of breeds typically affected by this condition were deeper at a more caudal...

Fracture assessment for a dissimilar metal weld of low alloy steel and Ni-base alloy

Recently, instances of SCC in Ni-base alloy weld metal of light water reactor components have been reported. Despite the possibility of propagation of SCC crack to the fusion line between low alloy steel (LAS) of pressure vessel and Ni-base alloy of internal structure, a fracture assessment method of dissimilar metal welded joint has not been established. The objective of this study is to investigate a fracture mode of dissimilar metal weld of LAS and Ni-base alloy for development of a fracture assessment method for dissimilar metal weld. Fracture tests were conducted using two types of dissimilar metal weld test plates with semi-elliptical surface crack. In one of the test plates, the fusion line lies around the surface points of the surface crack and the crack tips at the surface points have intruded into LAS. Material ahead of the crack tip at the deepest point is Ni-base alloy. In the other, the fusion line lies around the deepest point of the surface crack and the crack tip at the deepest point has intruded into LAS. Material ahead of the crack tip at the deepest point is LAS. The results of fracture tests using the former type of test plate reveal that the collapse load considering the proportion of ligament area of each material gives a good estimation for fracture load. That is, fracture assessment based on plastic collapse mode is applicable to the former type of test plate. It is also understood that a fracture assessment method based on the elastic-plastic fracture mode is suitable for the latter type of test plate.

The 3D analysis of the sagittal curvature of the femoral trochlea in the Chinese population

An unnatural design of the sagittal geometry of the femoral trochlea may cause abnormal patellofemoral kinematics and complications after knee arthroplasty. Most previous studies examined the sagittal curvature of the femoral trochlea on 2D parasagittal planes, which may not represent the true sagittal curvature of the complex 3D femoral trochlea. The current study evaluated the sagittal geometry of the femoral trochlea of 100 healthy Chinese subjects (50 women and 50 men) with 3D analysis. A close-fit sphere was generated on the surface of the medial and lateral trochlear articular surface, respectively. The radii of the spheres represented the sagittal radii of the femoral trochlear sagittal curvature. A cylinder was then established and its radius was adjusted to allow the deepest points of the curved trochlear groove touching the cylindrical surface. The radius of the cylinder represented the sagittal radius of the trochlear groove. In the men, the average radii of the curvature of the femoral trochlea were 18.8 ± 2.5 mm and 25.5 ± 2.8 mm for the medial and lateral femoral trochleas, respectively. In the women, the average radii of the curvature of the femoral trochlea were 20.2 ± 3.0 mm and 26.6 ± 2.7 mm for the medial and lateral femoral trochleas, respectively. The average radius of the cylinder of the trochlea groove was 19.6 ± 2.0 mm with a circular arc of 123.2° ± 13.0° in the men. In the women, the radius was 20.2 ± 1.7 mm with a circular arc of 127.9° ± 11.7°. The present study provided a reliable and consistent assessment of the sagittal geometry of the femoral trochlea in the Chinese population. The results of the current study may be helpful to improve the understanding of the knee kinematics and develop the physiological knee prostheses.

Creep fracture mechanics parameters for internal axial surface cracks in pressurized cylinders and creep crack growth analysis

In the present study, a low alloy Cr–Mo steel cylinder subjected to internal pressure at high temperature with a semi-elliptical crack located at the inner surface is considered. The creep crack driving force parameter C∗-integrals calculated by finite element (FE) method, are compared with results from previous studies, which indicates that empirical equations may be inaccurate under some conditions. A total of 96 cases for wide practical ranges of geometry and material parameters are performed to obtain systematic FE results of C∗-integral, which are tabulated and formulated in this paper. It is observed that the maximum C∗-integral may occur neither at the deepest point nor at the surface point when the aspect ratio is large enough and the value of C∗-integral is significantly sensitive to the crack depth ratio. Furthermore, based on the proposed equations for estimating C∗-integrals and a step-by-step analysis procedure, crack profile development, crack depth, crack length and remaining life prediction are obtained for surface cracks with various initial aspect ratios. It is found that when the crack depth ratio is increased, there is no obvious convergence of crack aspect ratio observed. The magnitude of half crack length increment is always minor compared with the crack depth increment. In addition, the remaining life is much more dependent on the surface crack depth than on the surface crack length.

The morphological features and developmental changes of the philtral dimple: A guide to surgical intervention in cases of cleft lip

ObjectiveThis study was undertaken to analyse in detail the morphological features of the philtral dimple and the developmental changes of philtral morphology, including a comparison with patients with a cleft lip. Patients and participantsFifty-five normal Japanese adults, seventy-five children and fifteen patients with complete unilateral cleft lip were referred for analysis. Design3D facial data were acquired with a non-contacting laser scanner. We calculated the desired linear and angular components, defining the features of the philtrum with analysing software. ResultsThe philtral dimple was morphologically expressed by the two different deepest points in the horizontal and sagittal sectional view, respectively. These decreased with age and did not show any correlation. In contrast, philtral measurements on the X–Y coordinates increased during the course of development. Most of the linear and angular variables in the patients with the cleft lip had exhibited greater values than the normal subjects, reflecting the deformed philtral morphology. ConclusionsTo obtain an optimally natural philtral construction accompanied by a symmetrical lip in cleft surgery, it is critical to take into consideration both the geometric features of the philtral depth and age-appropriate morphological features of the philtrum as objective criteria.

Quantitative comparison and analysis of sulcal patterns using sulcal graph matching: A twin study

The global pattern of cortical sulci provides important information on brain development and functional compartmentalization. Sulcal patterns are routinely used to determine fetal brain health and detect cerebral malformations. We present a quantitative method for automatically comparing and analyzing the sulcal pattern between individuals using a graph matching approach. White matter surfaces were reconstructed from volumetric T1 MRI data and sulcal pits, the deepest points in local sulci, were identified on this surface. The sulcal pattern was then represented as a graph structure with sulcal pits as nodes. The similarity between graphs was computed with a spectral-based matching algorithm by using the geometric features of nodes (3D position, depth and area) and their relationship. In particular, we exploited the feature of graph topology (the number of edges and the paths between nodes) to highlight the interrelated arrangement and patterning of sulcal folds. We applied this methodology to 48 monozygotic twins and showed that the similarity of the sulcal graphs in twin pairs was significantly higher than in unrelated pairs for all hemispheres and lobar regions, consistent with a genetic influence on sulcal patterning. This novel approach has the potential to provide a quantitative and reliable means to compare sulcal patterns.

Indonesian Fieldwide Application of Intelligent-Well Technology - A Case History

This article, written by Senior Technology Editor Dennis Denney, contains highlights of paper OTC 21063, ’Indonesian Operator's First Fieldwide Application of Intelligent-Well Technology - A Case History,’ by Kim Sam Youl, and Harkomoyo, SPE, Kodeco Energy Company and Doug Finley, SPE, Halliburton, prepared for the 2010 Offshore Technology Conference, Houston, 3-6 May. The paper has not been peer reviewed. A fieldwide application of intelligent-well-completion technology was used in Indonesia to commingle “free energy” from an overlying gas cap to support production from underlying oil reservoirs that typically have a high water cut. Previously, wells in this offshore field were developed with conventional gas lift completions that used gas supplied from outside the platform. The application of an “auto-gas-lift” (AGL) concept, an intelligent-well technology, eliminated the capital equipment associated with conventional gas lift completions along with the conventional downhole gas lift equipment. Introduction The KE-38 field is in the East Java basin, approximately 30 miles off the northern coast of Madura Island, Indonesia (Fig. 1). Water depth averages approximately 190 ft in this block. The oil columns are between 60 and 300 ft thick, with a 500-ft-thick gas cap (on average) and an underlying water zone. True vertical depth of the gas/oil contact is 4,500 to 5,000 ft subsea. Porosity of the oil rim ranges from 18 to 26%, and permeability ranges from 20 to 100 md. The reservoir is normally pressured, and productivity ranges from 5 to 20 bbl/(psi-D). Maximum bottomhole pressure and temperature are 2,200 psi and 195°F, respectively. The oil is a slightly waxy, 35°API crude. Given that the reservoir fluid is nearly saturated, initial production from the wells was with natural flow. However, because the flowline pressure is high (approximately 900 psi), these wells would require artificial lift during the initial stage of operation to begin flow and maintain the gas/liquid ratio to optimize the produced-oil rate. Conventional gas lift completions have a setting-depth limitation relating to the gas lift mandrel. The maximum setting angle is less than 60°. However, an AGL interval-control valve (ICV) is capable of being set in any trajectory angle and can be set at the deepest point in the wellbore to optimize oil production. The AGL completion enables altering the flow characteristics of a zone without mechanical intervention.

The Calculation of Stress Intensity Factors and the Analysis of Propagation Characteristic of Crack at Hole

This paper focusing on the crack at hole of guyed-mast’s ear-plate connecting cables and shaft of guyed-mast, adopting two degree of freedom crack propagation model, track the crack propagation according to the increment of the deepest point and the surface point on the crack front of crack at hole of guyed-mast’s ear-plate. The stress intensity factors of I,II and III type crack with given shape and size have been calculated via finite element method, and a numerical method of calculating stress intensity factors with any shape and size crack has been proposed; furthermore according to modified I, II and III type compound crack propagation velocity formula on the basis of Paris crack propagation velocity formula, we analyzed the changing of crack shape parameter a/c with crack size parameter a/T of crack at hole of ear-plate connecting cable and shaft of guyed-mast by numerical integration method and obtained the propagation characteristic.