• Proceedings of the Korean Geotechical Society Conference
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• 2003.03a
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• pp.681-688
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• 2003

Rock damage induced by blasting can not be avoided during tunnel construction and may affect tunnel stability. But the mutual interaction between tunnel blasting design and tunnel stability design is generally not considered. Therefore this study propose a methodology to take into considration the results of the blasting damage in tunnel stability design. Rock damage is evaluated by dynamic numerical analysis for the most common blasting pattern adopted in road tunnel. Damage zone is determined by using the continuum damage model which is expressed as a function of volumetric strain. And the damage effect is taken into account by the damaged rock stiffness and the damaged failure criteria in tunnel stability assessment. The extend of plastic zone and deformation increase compared to the case of not considering blast-induced rock damage.

• Journal of Korea Society of Digital Industry and Information Management
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• v.9 no.4
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• pp.95-101
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• 2013

MANET has an advantage that can build a network quickly and easily in difficult environment to build network. In particular, routing protocol that uses in existing mobile environment cannot be applied literally because it consists of only mobile node. Thus, routing protocol considering this characteristic is necessary. Malicious nodes do extensive damage to the whole network because each mobile node has to act as a router. In this paper, we propose technique that can detect accurately the suspected node which causes severely damage to the performance of the network. The proposed technique divides the whole network to zone of constant size and is performed simultaneously detection technique based zone and detection technique by collaboration between nodes. Detection based zone translates the information when member node finishes packet reception or transmission to master node managing zone and detects using this. The collaborative detection technique uses the information of zone table managing in master node which manages each zone. The proposed technique can reduce errors by performing detection which is a reflection of whole traffic of network.

• Structural Engineering and Mechanics
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• v.59 no.1
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• pp.123-132
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• 2016

Many military and commercial aging aircrafts flying beyond their design life may experience severe crack and corrosion damage, and thus lead to catastrophic failures. In this paper, were used in a finite element model to evaluate the effect of corrosion on the adhesive damage in bonded composite repair of aircraft structures. The damage zone theory was implemented in the finite element code in order to achieve this objective. In addition, the effect of the corrosion, on the repair efficiency. Four different patch shapes were chosen to analyze the adhesive damage: rectangular, trapezoidal, circular and elliptical. The modified damage zone theory was implemented in the FE code to evaluate the adhesive damage. The obtained results show that the adhesive damage localized on the level of corrosion and in the sides of patch, and the rectangular patch offers high safety it reduces considerably the risk of the adhesive failure.

• Journal of the Korean Geotechnical Society
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• v.35 no.1
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• pp.43-53
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• 2019

This paper described a result of finite element analysis considering sewerage damage scale and soil depth, in order to analyze quantitatively for cavity and relaxation zone of underground due to sewerage damage. The mechanical model, which was verified by previous studies, was applied to the finite element analysis. In addition, the mechanical behavior of the soil around the sewerage damage due to the soil loss was simulated by using the forced displacement. Based on finite element analysis results, characteristics of the void ratio distribution, ground subsidence, and shear stress distribution according to sewerage damage scale and soil depth were analyzed. And then, The boundaries of the underground cavity and relaxation zone were determined by using the shear stress reduction characteristics of the ground. Also, an occurrence scope of the cavity and relaxation zone was quantitatively evaluated by the change of sewerage damage scale and soil depth.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.4
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• pp.1194-1201
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• 1996

For the case of creep-fatigue interaction, the damage zone developed in front of the growing crack-tip during creep regime is important because it can affect the damage mechanism to be occured by the following fatigue load. These are studied in theis paper through proper consideration of the cavitiy-size dependent sintering stress which is approximated by polynomials. It is shown that the inclination of reversed damage zone size with respect to the applied load parameter can be explained by considering realistic sintering stress distribution. However, the resultant stress field has $r^{1/2+\theta}$ singularity, regardliss of the profile of variable sintering stress, which is the same to that case solved for constant sintering stress.

• Composites Research
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• v.21 no.4
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• pp.22-28
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• 2008

The composite joint has become an important research area because the structural efficiency of a structure with a joint is determined by its joints rather than by its basic structure since the joints are often the weakest areas in composite structures. In this paper, the strengths of adhesive joints consisting of metal and composites were predicted and tested by the maximum strain theory and damage zone theory. Nonlinear finite element analyses of adhesive Joints considering the material nonlinearity of the adhesive layer were performed. From the tests and analyses, the strengths of the adhesive joints could be predicted to within 22.2% using the damage zone ratio.

• Earthquakes and Structures
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• v.25 no.4
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• pp.235-247
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• 2023

Bingöl, a city in eastern Türkiye, is located at a very close distance to the Karlıova Region which is a junction point of the North Anatolian Fault Zone and Eastern Anatolian Fault Zone. By bilateral step over of North Anatolian Fault Zone and Eastern Anatolian Fault Zone each other there occurred NorthWest-SouthEast extended right-lateral and NorthEast-SouthWest extended left-lateral fault zones. In this paper, a typical school building located in Bingöl Çeltiksuyu was selected as the case study. Information on the school building and Bingöl Earthquake (2003) have been given in the paper. This study aimed to determine the fragility curves of the school building according to HAZUS 2022, Turkish Seismic Codes 1998, 2007 and 2018. These codes have been introduced in terms of damage limits. Incremental dynamic analysis is a parametric analysis method that has recently emerged in several different forms to estimate more thoroughly structural performance under seismic loads. Fragility analysis is commonly using to estimate the damage probability of buildings. Incremental Dynamic Analysis have performed, and 1295 Incremental Dynamic Analysis output was evaluated to obtain fragility curves. 20 different ground motion records have been selected with magnitudes between 5.6M and 7.6M. Scaling factors of these ground motions were selected between 0.1g and 2g. Comparison has been made between HAZUS 2022 and Turkish Seismic Codes 1998, 2007 and 2018 in terms of damage states and how they affected fragility curves. TSC 1998 has more conservative strictions along with TSC 2018 than TSC2007 and HAZUS moderate and extensive damage limits.

• Interaction and multiscale mechanics
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• v.1 no.2
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• pp.279-301
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• 2008

This paper develops a 3D homogenization based continuum damage mechanics (HCDM) model for fiber reinforced composites undergoing micromechanical damage under monotonic and cyclic loading. Micromechanical damage in a representative volume element (RVE) of the material occurs by fiber-matrix interfacial debonding, which is incorporated in the model through a hysteretic bilinear cohesive zone model. The proposed model expresses a damage evolution surface in the strain space in the principal damage coordinate system or PDCS. PDCS enables the model to account for the effect of non-proportional load history. The loading/unloading criterion during cyclic loading is based on the scalar product of the strain increment and the normal to the damage surface in strain space. The material constitutive law involves a fourth order orthotropic tensor with stiffness characterized as a macroscopic internal variable. Three dimensional damage in composites is accounted for through functional forms of the fourth order damage tensor in terms of components of macroscopic strain and elastic stiffness tensors. The HCDM model parameters are calibrated from homogenization of micromechanical solutions of the RVE for a few representative strain histories. The proposed model is validated by comparing results of the HCDM model with pure micromechanical analysis results followed by homogenization. Finally, the potential of HCDM model as a design tool is demonstrated through macro-micro analysis of monotonic and cyclic damage progression in composite structures.

• Geomechanics and Engineering
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• v.21 no.3
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• pp.289-300
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• 2020

Estimating the damage induced by an explosion around a blast hole has always been a challenging issue in geotechnical engineering. It is difficult to determine an exact dimension for damage zone since many parameters are involved in the formation of failures, and there are some uncertainties lying in these parameters. Thus, the present study adopted a probabilistic approach towards this problem. First, a reliability model of the problem was established and the failure probability of induced damage was calculated. Then, the corresponding exceedance risk curve was developed indicating the relation between the failure probability and the cracked zone radius. The obtained risk curve indicated that the failure probability drops dramatically by increasing the cracked zone radius so that the probability of exceedance for any crack length greater than 4.5 m is less than 5%. Moreover, the effect of each parameter involved in the probability of failure, including blast hole radius, explosive density, detonation velocity, and tensile strength of the rock, was evaluated by using a sensitivity analysis. Finally, the impact of the decoupling ratio on the reduction of failures was investigated and the location of its maximum influence was demonstrated around the blast point.

• Structural Engineering and Mechanics
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• v.75 no.1
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• pp.101-108
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• 2020

The present study intends to analyze damage in thin-walled steel cylinders undergoing constant internal pressure and thermal cycles through use of anisotropic continuum damage mechanics (CDM) model coupled with nonlinear kinematic hardening rule of Chaboche. Materials damage in each direction was defined based on plastic strain and its direction. Stress and strain distribution over wall-thickness was described based on the CDM model and the return mapping algorithm was employed based on the consistency condition. Plastic zone expansion across the wall thickness of cylinders was noticeably affected with change in internal pressure and temperature gradients. Expansion of plastic zone over wall-thickness at inner and outer surfaces and their boundaries demarking elastic and plastic regions was attributed to the magnitude of damage induced over thermomechanical cycles on the thin-walled samples tested at various pressure stresses.