• 터널과지하공간
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• 제7권1호
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• pp.31-38
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• 1997

Residual shear strength should be taken into consideration as well as peak one when analysing stability of slopes constituted by weathered rock or overconsolidated soils since such materials could be subjected to progressive failure mechanism. When landslide of a slope is related to progressive failure phenomenon, the failure might occur even though shear strength of the slope materials does not reach their residual shear strength over the whole slip surface. Therefore, stability of the slope concerned may be overstimated or underestimated when using only its peak or residual shear srength parameters. Mechanical description for progressive failure phenomenon is given by Bjerrum(1967). In parameters. Mechanical description for progressive failure phenomenon is given by Bjerrum(1967). In this study, his theory has been extended to estimate the distance of failed zone for a plane slope and the results calculated by this extended equatio has been compared with that obtained by numerical modelling using FLAC. In addition, stress state on the slip surface has been, in detail, analysed to understand failure mechanism when a limited progressive failure occurs. Effects of mechanical and hydraulic factors on progressive failure have also been analysed.

• 대한조선학회논문집
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• 제52권1호
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• pp.52-60
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• 2015

In the present study, an evaluation method for progressive failure of composite laminates has been proposed based on Puck's failure criterion and damage mechanics. The initial failure (or initiation of crack/delamination) has been assessed using Puck's failure criterion, and the progressive failure (or growth of crack/delamination) has been evaluated using fiber- and matrix-dependent damage variables. Based on Puck's failure criterion-damage mechanics coupling theories, the ABAQUS user-defined subroutine UMAT has been developed in order to analyze the progressive failure of glass/carbon fiber-reinforced composite laminates efficiently. In addition, the developed subroutine has been applied to progressive failure problem of industrial composite laminates, and the analysis results has been compared to experimental results which have been already reported in publications. It was confirmed that the simulation results were coincided well with the reported composite failure results.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2017년도 제48회 춘계학술대회논문집
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• pp.936-938
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• 2017

본 논문에서는 발사체 및 무기체계의 연소관 등에 적용되고 있는 복합재의 볼트체결부에 대한 점진적 파손 해석을 수행하였다. 해석에 사용된 Hashin 파손 판정식은 복합재 파손모드에 따라 섬유 인장 파손 모드(Fiber tensile failure mode), 섬유 압축 파손 모드(Fiber compressive failure mode), 기지 인장 파손 모드(Matrix tensile failure mode), 기지 압축 파손 모드(Matrix compressive failure mode)의 4가지 모드로 고려되었으며, 이를 이용해 user subroutine인 UMAT을 개발하였다. 점진적 파손 해석을 통해 복합재 볼트체결부에 대한 파손강도를 예측 하였으며, 이를 시편 시험 결과와 비교하였다.

• Communications for Statistical Applications and Methods
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• 제23권1호
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• pp.57-70
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• 2016

Type-II progressive censoring is one of the censoring methods frequently used in clinical studies, reliability trials, quality control of products and industrial experiments. Sometimes in Type-II progressive censoring experiments, the failure rate is low so the waiting time to observe the $m^{th}$ failure will be very long; however, the experimenter may have to terminate the experiment before a predetermined time. In this article, if two generalized types of Type-II progressive censoring are reminded, we then make some changes in the removal method of Type-II progressive censoring such that without reducing the deduction quality, the termination time of the experiment decreases. This can be done with decreasing withdraws throughout the steps of the experiment with a special reasonable method. A simulation study is done and the results are tabulated at the end of this article for a comparison between introduced method and Type-II progressive censoring.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1994년도 가을 학술발표회 논문집
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• pp.231-234
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• 1994

Concentrated stresses due to the tunnel excavation easily cause failure around opening in the soft rock mass layer. Thus, while excavatng tunnel in the soft rock mass layerm it is very important to predict the possibility of failure or yielding zones around tunnel boundary. There are two typical methods to predict these; 1) the analysis of field monioring data and 2) numerical analysis. In this study, it was attempted to describe the time-dependent or progressive rock mass manner due to the continuous failure and fracturing caused by surrounding underground openings using the second method. In order to apply the effects of progressive failure underground, an iterative technique was used with the Hoek and Brown rock mass failure theory. By developing and simulating, three different shapes of twin tunnels, this research simulated and estimated the proper size of critical pillar width between tunnels, distributed stresses on the tunnel sides, and convergences of tunnel crowns. Moreover, results out progressive failure technique based on the Hoek and Brown theory were compared with the results out of Mohr-Coulomb theory.

• 한국지반공학회지:지반
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• 제13권6호
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• pp.139-146
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• 1997

기초파괴는 일반적으로 변형이 집중되어 하나 또는 그 이상의 파괴면이 발생되어, 기초의 관입과 더불어 파괴면은 점진적으로 형성된다. 본 논문의 목적은 수치적으로 기초의 극한지지력 및 진행성 파괴거동을 파악할 수 있는가 하는 가능성을 검토하는데 있다. 대변형이론과 변형률 연화이론을 사용하여 비배수 상태인 점토지반의 기초에 대한 진행성 파괴거동에 대하여 분석하였다. 본 논문에서는 기초의 진행성 파괴과정과 완전한 하중 변위곡선을 해석하기 위한 수치해석 방법에 대하여 논하였다. 해석결과, 띠기초의 피크 이후의 지반파괴거동 및 진행성 파괴과정에 대한 명확한 수치적 해석가능성을 보여주었다.

• International Journal of Aeronautical and Space Sciences
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• 제18권3호
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• pp.436-449
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• 2017

In this paper, the damage and failure behavior of triaxially braided textile composites was studied using progressive failure analysis. The analysis was performed at both micro and meso-scales through iterative cycles. Stress based failure criteria were used to define the failure states at both micro- and meso-scale models. The stress-strain curve under uniaxial tensile loading was drawn based on the load-displacement curve from the progressive failure analysis and compared to those by test and computational results from reference for verification. Then, the detailed failure initiation and propagation was studied using the verified model for both tensile and compression loading cases. The failure modes of each part of the model were assessed at different stages of failure. Effect of ply stacking and number of unit cells considered were then investigated using the resulting stress-strain curves and damage patterns. Finally, the effect of matrix plasticity was examined for the compressive failure behavior of the same model using elastic, elastic - perfectly plastic and multi-linear elastic-plastic matrix properties.

• Composites Research
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• 제34권2호
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• pp.101-107
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• 2021

복합재료를 활용하여 설계되는 구조물은 각 부품들의 조립, 체결부를 갖게 된다. 이러한 연결 또는 조인트는 구조에서 잠재적으로 취약 부분이 될 수 있다. 복합재료 볼트 조인트의 파손모드는 구조 안전성을 위해 베어링 파손모드로 설계된다. 베어링 파손모드로 파괴되는 복합재료 볼트 조인트의 하중-변위 관계는 초기 파손 발생 후 비선형 거동을 보이며, 점진적인 파손을 보인다. 이러한 비선형적이고 점진적인 복합재료 볼트 조인트의 파손거동을 정확히 예측하기 위해 본 연구에서는 기존의 파손해석 모델에서 전단 손상변수 계산 과정에 수정을 수행하였다. 수정된 파손해석 모델을 이용하여 복합재료 볼트 조인트의 베어링 응력-베어링 변형률 결과를 예측하였으며, 기존 수정되지 않은 해석모델과 비교를 통해 수정된 모델의 유효성을 입증하였다.

• 콘크리트학회논문집
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• 제11권3호
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• pp.181-192
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• 1999

The progressive failure following strain localization in concrete can be analyzed effectively using finite element modeling of fracture process zone of concrete with a finite element embedded discontinuity. In this study, a finite element with embedded discontinuous line is utilized for the analysis of progressive failure in concrete. The finite element with embedded discontinuity is a kind of discrete crack element, but the difficulties in discrete crack approach such as remeshing or adding new nodes along with crack growth can be avoided. Using a discontinuous shape function for this element, the displacement discontinuity is embedded within an element and its constitutive equation is modeled from the modeling of fracture process zone. The element stiffness matrix is derived and its dual mapping technique for numerical integration is employed. Then, a finite element analysis program with employed algorithms is developed and failure analysis results using developed finite element program are verified through the comparison with experimental data and other analysis results.

• Computers and Concrete
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• 제12권3호
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• pp.351-375
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• 2013

Post-punching resistance of a flat slab can help redistribute the gravity loads and resist progressive collapse of a structure following initial damage. One important difficulty with accounting for the post-punching strength of a slab is the discontinuity that develops following punching shear. A numerical simulation technique is proposed here to model and evaluate post-punching resistance of flat slabs. It is demonstrated that the simulation results of punching shear and post-punching response of the model of a slab on a single column are in good agreement with corresponding experimental data. It is also shown that progressive collapse due to a column removal (explosion) can lead to punching failure over an adjacent column. Such failure can propagate throughout the structure leading to the progressive collapse of the structure. Through post-punching modeling of the slab and accounting for the associated discontinuity, it is also demonstrated that the presence of an adequate amount of integrity reinforcement can provide an alternative load path and help resist progressive collapse.