• Title, Summary, Keyword: Fracture

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Size-effect of fracture parameters for crack propagation in concrete: a comparative study

  • Kumar, Shailendra;Barai, S.V.
    • Computers and Concrete
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    • v.9 no.1
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    • pp.1-19
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    • 2012
  • The size-effect study of various fracture parameters obtained from two parameter fracture model, effective crack model, double-K fracture model and double-G fracture model is presented in the paper. Fictitious crack model (FCM) for three-point bend test geometry for cracked concrete beam of laboratory size range 100-400 mm is developed and the different fracture parameters from size effect model, effective crack model, double-K fracture model and double-G fracture model are evaluated using the input data obtained from FCM. In addition, the fracture parameters of two parameter fracture model are obtained using the mathematical coefficients available in literature. From the study it is concluded that the fracture parameters obtained from various nonlinear fracture models including the double-K and double-G fracture models are influenced by the specimen size. These fracture parameters maintain some definite interrelationship depending upon the specimen size and relative size of initial notch length.

Prediction of Fracture Strains for DP980 Steel Sheets for a Wide Range of Loading Paths (다양한 하중경로에서의 DP980 강판의 파단변형률 예측에 관한 연구)

  • Park, N.;Huh, H.
    • Transactions of Materials Processing
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    • v.24 no.3
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    • pp.176-180
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    • 2015
  • The current study is concerned with the prediction of fracture strains for DP980 steel sheets over a wide range of loading paths. The use of DP980 steel is increasing significantly in automotive industries for enhanced safety and higher fuel efficiency. The material behavior of advanced high-strength steels (AHSSs) sheets sometimes show unpredictable and sudden fracture during sheet metal forming. A modified Lou-Huh ductile fracture criterion is utilized to predict the formability of AHSSs because the conventional forming limit diagram (FLD) constructed based on necking is unable to evaluate the formability of AHSSs sheets. Fracture loci were extracted from three dimensional fracture envelopes by assuming the plane-stress condition to evaluate equivalent plastic strains at the onset of fracture for a wide range of loading paths. Three different types of specimens -- pure shear, dog-bone and plane strain grooved -- were utilized for tensile testing to calibrate the fracture model of DP980 steel sheets. Fracture strains of each loading path were evaluated such that there shows little deviation between fracture strains predicted from the fracture model and the experimental measurements. From the comparison, it is clearly shown that the three dimensional fracture envelopes can accurately predict the onset of the fracture of DP980 steel sheets for complicated loading conditions from compressive loading to shear loading and to equibiaxial tensile loading.

Influence of Hip Fracture on Knee Pain During Postoperative Rehabilitation

  • Kim, Hee-Ju;Lee, Seong Jae;Hyun, Jung Keun;Kim, Seo-Young;Kim, Tae Uk
    • Annals of Rehabilitation Medicine
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    • v.42 no.5
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    • pp.682-689
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    • 2018
  • Objective To investigate whether fracture type, surgical procedure, or fracture grade affect knee pain during postoperative rehabilitation after a hip fracture. Methods We conducted a retrospective case-controlled study of 139 patients during postoperative rehabilitation after surgery for hip fractures. Patients were divided into two groups: patients experiencing knee pain during the first week of postoperative rehabilitation, and patients without knee pain. We compared the types of fracture, surgical procedure, and fracture grade between the two groups. Results We enrolled 52 patients (37.4%) with knee pain during the first weeks of postoperative rehabilitation. For type of fracture, knee pain was more common with intertrochanteric fracture than with femur neck fracture (48.8% vs. 21.1%, respectively; p=0.001). For the surgical procedure, there was no significant difference between the groups. For the fracture grade, the grades classified as unstable fractures were more common in the group of intertrochanteric fracture patients with knee pain than in those without knee pain (74.1% vs. 36.4%, respectively; p=0.002). Conclusion Intertrochanteric fracture affected knee pain after hip fracture surgery more than did femur neck fracture, particularly in unstable fractures. Furthermore, there was no difference in each fracture type according to the surgical procedure. Careful examination and management for knee pain is needed in patients with hip fracture surgery.

Evaluation of Critical Notch radius using Notch/Crack Critical Average Stress Fracture Model (노치/균열 임계평균응력 파손모델을 이용한 임계노치반경 평가)

  • 김재훈;김덕회;김기수;안병욱
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.1358-1361
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    • 2003
  • In this study, intrinsic static/dynamic fracture toughness of Al 7175-T74 are evaluated from the apparent static/dynamic toughness of notched specimen. The notch/crack critical average stress fracture model is suggested to establish the relationship to predict the intrinsic fracture toughness from the apparent fracture toughness of a notched specimen. The notch/crack critical average stress fracture model is established using the relation between the notch root radius and the effective distance calculated by finite element analysis. It is conclude that the true fracture toughness can be estimated from test results of apparent fracture toughness measured by using a notched specimen. Also, critical notch root radius can be predicted by notch/crack critical average stress fracture model.

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Tillaux Fracture in an Adolescent with a Trimalleolar Ankle Fracture (족관절 삼과 골절과 동반된 청소년기 Tillaux 골절)

  • Park, Seok Kyun;Chae, Soo Uk
    • Journal of Trauma and Injury
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    • v.28 no.4
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    • pp.280-283
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    • 2015
  • The adolescent Tillaux fracture is an avulsion fracture of the anterolateral corner of the distal tibial epiphysis caused by external rotation of the foot. This type of fracture occurs during epiphyseal fusion in adolescence. A difficult to detect Tillaux fracture was discovered on a preoperative radiograph, such fractures have rarely been reported to accompany a predominantly adult-type ankle fracture. Especially, to the best of our knowledge, no case of a trimalleolar ankle fracture in an adolescent with a Tillaux fracture has been reported. Thus, we present a case of a trimalleolar ankle fracture in a 15-year-old adolescent with a Tillaux fracture who was successfully treated surgically.

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Fractures of the dog in Taegu area (대구지방에서 발생한 개의 골절)

  • 김대영;장인호
    • Journal of Veterinary Clinics
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    • v.15 no.1
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    • pp.222-227
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    • 1998
  • This survey was based on the data of one hundred four dogs with 108 case,T of fracture admitted to the veterinary teaching hospital, College of Veterinary Medicine, Kyungpook National University and 24 private small animal hospitals from January, 1995 to Decemberi 1996. The results were analyzed as following criteria; the distribution of fractures causes of fractured age and sexual distributions month of the most frequencel total body weights presence of communicating external wound, extent of damaged direction of fracture line, location of fracture liner fracture managements fixations methods, fixations methods according to location of fracture. The results of survey were as follow: 1. Main distribution of fracture; radius . ulna (23.1%).2. Causes of fracture; road toraffic accident (39.4 T,). 3. Age; over 24 months (27.9%). 4. Sex; male (53.89)), female (46.2%). 5. Month of the most frequence; July (14.4%) 6. Total body weight: 2-5 kg (45.27)). 7. Presence of communicating external wound; closed fracture (94.2%). 8. Extent of damage; complete fracture (92.6%). 9. Direction of fracture line: comminuted fracture (27.8 To). 10. Location of fracture line; diaphysis (62.0%). 11. Fracture management; open reduction (58.3% ). 12. Fixation methods; not treat (22.2%). 13. Fixation methods according to location of fracture; radius ulna-Kirschner wire fixation (45.5%), femur. shaft-intramedullary pinning (71.4%), pelvis-bone plate (53.3%), metacarpus-not treat, Kirschner wire fixation (each 30.8%).

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THE PROGNOSIS OF THE TEETH IN THE MANDIBULAR FRACTURE LINES (하악골 골절선상에 위치한 치아의 예후에 관한 연구)

  • Song, Jae-Chul;Chang, Ic-Jun;Chin, Byung-Rho
    • Journal of the Korean Association of Oral and Maxillofacial Surgeons
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    • v.26 no.5
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    • pp.507-513
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    • 2000
  • Objective : The purpose of this study is to evaluate the vitality of the teeth in and adjacent to the mandibular fracture line according to variable conditions of fracture and to establish the protocol of treatment of fracture line teeth. Materials and Methods : The vitality of 97 teeth in fracture line and 104 teeth adjacent to fracture line of 52 patients were invested preoperatively. Of these, 66 teeth in fracture line and 72 teeth adjacent to fracture line were monitored at least 6 months after operation. An electric pulp tester was used to measure pulpal response. The relationships between the vitality of teeth in variable time(preoperation, immediate post-operation; within 1 week after operation, and 6 months after operation) and variable conditions of fracture(horizontal, vertical gap of fracture line, the number of fracture line)were evaluated statistically. Result : The vitality of fracture line teeth in the 6 months after operation statistically differed by the vertical gap of fracture line and the number of fracture line. The vitality of fracture line adjacent teeth in the immediate post-operation only statistically differed by the vertical gap of fracture line. There were statistically differences between preoperative EPT value and vitality of fracture line teeth on 6 months after operation. There were 5 cases of complications including periapical and periodontal abscess. Of these, only one tooth was extracted and the others were well treated with endodontic treatment and subgingival curettage. Conclusion : It is recommended to retain teeth and to monitor the vitality of teeth in and adjacent to fracture line, unless there is an absolute indication for extraction.

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Modeling of Multi-Stage Hydraulic Fracture Propagation (다단계 수압파쇄균열 전파 모델링 연구)

  • Jang, Youngho;Sung, Wonmo
    • Journal of the Korean Institute of Gas
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    • v.19 no.5
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    • pp.13-19
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    • 2015
  • This paper presents a hydraulic fracture propagation model to describe propagation more realistically. In propagating the hydraulic fractures, we have used two criteria: maximum tangential stress to determine the fracture initiation angle and whether a hydraulic fracture intersects a natural fracture. The model was validated for the parameters relevant to fracture propagation, such as initiation angle and crossing ability through natural fracture. In order to check whether a hydraulic fracture crosses a natural fracture, the model results on crossing state excellently matched with the experimental data. In the sensitivity analysis for direction of maximum horizontal stress, frictional coefficient of fracture interface, and natural fracture orientation, the results show that hydraulic fracture intersects natural fracture, and then, propagated suitably with theoretical results according to fracture interaction criterion. In comparison of this model against vertical fracture approach, it was ascertained that there are discrepancies in fracture connectivity and stimulated reservoir volume.

Clinical Analysis for the Correlation of Intra-abdominal Organ Injury in the Patients with Rib Fracture

  • Park, Seong-Sik
    • The Korean Journal of Thoracic and Cardiovascular Surgery
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    • v.45 no.4
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    • pp.246-250
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    • 2012
  • Background: Although it is rare for the fracture itself to become a life threatening injury in patients suffering from rib fracture, the lives of these patients are occasionally threatened by other associated injuries. Especially, early discovery of patients with rib fracture and intra-abdominal organ injury is extremely important to the prognosis. This study analyzed the link between rib fracture and intra-abdominal injury to achieve improved treatment. Materials and Methods: Among trauma patients that had visited the hospital emergency room from January 2007 to December 2009, a retrospective study was conducted on 453 patients suffering from rib fracture due to blunt trauma. Rib fracture was classified according to location (left, right, and bilateral), and according to level (upper rib fracture [1-2nd rib], middle rib fracture [3-8th rib], and lower rib fracture [9-12th rib]). The researched data was statistically compared and analyzed to investigate the correlation between the location, level, and number of rib fracture and intra-abdominal organ injury. Results: Motor vehicle injury was found to be the most common mechanism of injury with 208 cases (46%). Associated injuries accompanied with rib fracture were generated in 276 cases (61%). Intra-abdominal organ injury was discovered in 97 cases (21%). Liver injury was the most common intra-abdominal injury associated with rib fracture with 39 cases (40%), followed by spleen injury, with 23 cases (23%). Intra-abdominal injury according to level of rib fracture was presented as upper rib fracture in 11 cases (11%), middle rib fracture in 31 cases (32%), and lower rib fracture in 55 cases (57%), thus verifying that intra-abdominal injuries were commonly accompanied in lower rib fractures (p=0.03). In particular, significant increase of intra-abdominal injury was presented in fractures below the 8th rib (p=0.03). The number of intra-abdominal injuries requiring emergency operations was significantly higher in patients with more than 6 rib fractures (p=0.04). Conclusion: Intra-abdominal organ injury is more common in patients with lower rib fracture, especially fractures below the 8th rib. Intra-abdominal organ injuries generated in multiple rib fracture patients with more than 6 fractures significantly higher severity. These cases must be thoroughly inspected and carefully observed as there is possibility of emergency operation.

Influence of softening curves on the residual fracture toughness of post-fire normal-strength concrete

  • Yu, Kequan;Lu, Zhoudao
    • Computers and Concrete
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    • v.15 no.2
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    • pp.199-213
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    • 2015
  • The residual fracture toughness of post-fire normal-strength concrete subjected up to $600^{\circ}C$ is considered by the wedge splitting test. The initial fracture toughness $K_I^{ini}$ and the critical fracture toughness $K_I^{un}$ could be calculated experimentally. Their difference is donated as the cohesive fracture toughness $K_I^c$ which is caused by the distribution of cohesive stress on the fracture process zone. A comparative study on determining the residual fracture toughness associated with three bi-linear functions of the cohesive stress distribution, i.e. Peterson's softening curve, CEB-FIP Model 1990 softening curve and Xu's softening curve, using an analytical method is presented. It shows that different softening curves have no significant influence on the fracture toughness. Meanwhile, comparisons between the experimental and the analytical calculated critical fracture toughness values further prove the validation of the double-K fracture model to the post-fire concrete specimens.