• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.12
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• pp.3892-3898
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• 1996

In this study, the prediction of the fatigue life as well as the extimation of the characteristics of fatigue cumulative damage on GFRP under random loading were performed. The constant amplitude tests and the ramdom loading test were carried on notched GFRP specimens with a circular hole. Random waves were generated with a micro-computer and had wide band spectra. Since it is useful that the prediction of fatigue life ot the given load sequences is based on S-N curves under constant amplitude loading, the estimation of equivalent stress is done on every random waves. The equivalent stress wasat first estimated by Miner's rule and then by the proposed model which was based on Hashin-Rotem's comulative damage theory regarding nonlinear fatigue cumulative damage behavior. The fatigue lives were predicted from each equivalent stress evaluated. And each predicted fatigue llife was compared with experimental results. The number of cycles of random loads were counted by mean-cross counting method. The reuslts showed that the fatigue life predicted by proposed model was correlated well with the experimental results in comparison with Miner's model.

• Computers and Concrete
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• v.27 no.2
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• pp.153-162
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• 2021

This paper aims to simulate the isotropic elastic damage theory of Liu Jun (2012) using the self-programmed UMAT subroutine in the interface of ABAQUS. Liu Jun (2012)'s method based on the mechanic theory can not be used interactively with the currently commonly used finite element software ABAQUS. The advantage of this method in the paper is that it can interact with ABAQUS and provide a constitutive program framework that can be modified according to user need. The model retains the two scalar damage variables and the corresponding two energy dissipation mechanisms and damage criteria for considering the tensile and compressive asymmetry of concrete. Taking C45 concrete as an example, the relevant damage evolution parameters of its tensile and compressive constitutive model are given. The study demonstrates that the uniaxial tensile stress calculated by the subroutine is almost the same as the Chinese Concrete Design Specification (GB50010) before the peak stress, but ends soon after the peak stress. The stress-strain curve of uniaxial compression calculated by the subroutine is in good agreement with the peak stress in Chinese Concrete Design Specification (GB50010), but there is a certain deviation in the descending stage. In addition, this paper uses the newly compiled subroutine to simulate the shear bearing capacity of the shear key in a new structural system, namely the open-web sandwich slab. The results show that the damage constitutive subroutine has certain reliability.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.6 no.4
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• pp.79-88
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• 1986

A nonlinear cumulative damage theory, which can model the effects of the magnitude and sequence of variable amplitude fatigue loadings, is proposed. The concrete beam specimens are prepared and tested in four-point flexural loading conditions. The variable-amplitude fatigue loadings in two and three stages are considered. The present experimental study indicates that the fatigue failure of concrete is greatly influenced by the magnitude and sequence of applied, variable-amplitude fatigue loadings. It is seen that the linear damage theory proposed by Palmgren and Miner is not directly applicable to the concrete under such loading cases. The sum of the cumulative damage is found to be greater than 1 when the magnitude of fatigue loading is gradually increased and less than 1 when the magnitude of fatigue loading is gradually decreased. The proposed nonlinear damage theory, which includes the effects of the magnitude and sequence of applied fatigue loadings, allows more realistic fatigue analysis of concrete structures.

• Journal of Physiology & Pathology in Korean Medicine
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• v.22 no.4
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• pp.733-739
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• 2008

It was said that the epigastric region was the outbreak region of chest bind on Shanghanlon. But successive medical men annotated the epigastric region as the chest, which caused the misunderstanding that chest bind was a chest trouble. However Youzaijing, a medical man in Qing dynasty, presented that the epigastric region meant stomach and the middle of stomach did intestines, comparing Dachengqi-tang with Daxianxiong-tang. This view agreed with Huatuo's six-region-transmutation theory. Taojiean and Zhangjingyue also criticized on the six-meridian-transmutation theory, proposing that the change of cold damage didn't go by the fixed rules. This reflected the oriental medical pathologic view that pathogen invaded and advanced to the weak region by the relations between healthy qi and pathogen, and it criticized on the doctrinarian interpretation of Shanghanlon as Neijing. Huatuo insisted that stomach was the final stage of cold damage by presenting that theory. And this theory became a philological basis on Youzaijing's pathologic view.

• Journal of Physiology & Pathology in Korean Medicine
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• v.24 no.1
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• pp.1-8
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• 2010

They have brought many inconsistencies by making much of Wang Sukhwa's six-meridian-transmutation-theory based on Yeollon, Somun in Oriental traditional medicine. On this many medical men such like Hwa Ta have raised objections to that or insisted on its repeal. Wang Geungdang and Yang Soi posed the problem of editing tables of contents, Bang Yujip and Ga Geum etc. gave explanations of fields of six-meridian, Un Cheolcho and Jang Gyeongak etc. presented cause and direction of transmutation. And Gilik Dongdong insisted on its repeal. Sanghannon was the theory that was arranged various experiences of acute epidemic diseases. But they didn't recognize the differences between analogous epidemic diseases, regarded as the same things in Oriental traditional medicine, and this made many inconsistencies. This is the reason why many medical men raised objections to Wang Sukhwa's six-meridian-transmutation-theory.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.857-860
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• 2006

In the present study, the method and procedure for analysis of impact damage behavior for concrete under penetration and perforation of projectile is investigated. Conservation law, equation of motion, initial and boundary conditions, and FEM formulation are introduced and derived respectively. Specially, the constitutive equation which rate-dependent damage combined with rate-dependent plasticity within the appropriate framework of theory of thermodynamics is examined. This paper aimed at the review with respect to impact damage models for concrete to develop that model. This paper is a basis research for the development of impact damage model for concrete.

• Journal of Korean Medical classics
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• v.22 no.1
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• pp.87-91
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• 2009

"Treatise on cold damage and miscellaneous disease" is a ancient formula records on keeping in good health, provided "Internal classic" is a ancient codes on keep in good health. It can be inferred that Zhang Zhongjing was a first inheritor of academic ideology from "formula followed by establishment of the therapeutic principles". Before writing and compiling the "Treatise on cold damage and miscellaneous disease", Zhang zhongjing got the essence of "Internal classic" after composing and utilizing "Plain Questions", "Miraculous pivot and classic of difficult issues", so all the theory foundations of "Treatise on cold damage and miscellaneous disease" came from "Internal classic". The keynote of internal classic lies in obeying the Yin and Yang in natural world and preserving and maintaining the yang-qi of human body to attain the longest life-span. Zhang assimilated the essence of "Internal classic" and then generated a new ideological system - "Treatise on cold damage and miscellaneous disease" when studying it. This article is to expound ideology inheritance of keeping in good health by protecting Yang in "Internal classic" from analyzing the usage of Guizhi in "treatise on cold damage diseases".

• Journal of the Korean Society of Hazard Mitigation
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• v.1 no.2 s.2
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• pp.63-74
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• 2001

In this paper the feasibility of Nondestructive Damage Detection (NDD) in large structures is demonstrated via simulating vibration monitoring of such structures. The theory of NDD for truss type structures is formulated. To examine the feasibility of the theory, a finite element model of a 3-D truss structure, which consists of sixteen bays and includes 246 elements, is developed to simulate damage. Four damage cases are simulated numerically and the cases range from the structure being damaged in one location to the structure being damaged in three locations. For the given modal parameters, this study reveals very good results for small amounts of damage as well as large damage.

• Smart Structures and Systems
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• v.3 no.4
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• pp.439-454
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• 2007

In this paper a damage imaging technique using pre-stack migration is developed using Lamb (guided) wave propagation in composite structures for imaging multi damages by both numerical simulations and experimental studies. In particular, the paper focuses on the experimental study using a finite number of sensors for future practical applications. A composite laminate with a surface-mounted linear piezoelectric ceramic (PZT) disk array is illustrated as an example. Two types of damages, one straight-crack damage and two simulated circular-shaped delamination damage, have been studied. First, Mindlin plate theory is used to model Lamb waves propagating in laminates. The group velocities of flexural waves in the composite laminate are also derived from dispersion relations and validated by experiments. Then the pre-stack migration technique is performed by using a two-dimensional explicit finite difference algorithm to back-propagate the scattered energy to the damages and damages are imaged together with the excitation-time imaging conditions. Stacking these images together deduces the resulting image of damages. Both simulations and experimental results show that the pre-stack migration method is a promising method for damage identification in composite structures.

• Geomechanics and Engineering
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• v.15 no.1
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• pp.677-686
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• 2018

Aimed at serious casing damage problem during the process of oilfield development by injecting water, based on seepage mechanics, fluid mechanics and the theory of rock mechanics, the multi-physics coupling theory was also taken into account, the mathematical model for production of petroleum with water flooding was established, and the method to solve the coupling model was presented by combination of Abaqus and Eclipse software. The Q9G3 block in Jibei oilfield was taken for instance, the well log data and geological survey data were employed to build the numerical model of Q9G3 block, the method established above was applied to simulate the evolution of seepage and stress. The production data was imported into the model to conduct the history match work of the model, and the fitting accuracy of the model was quite good. The main mechanism of casing damage of the block was analyzed, and some wells with probable casing damage problem were pointed out, the displacement of the well wall matched very well with testing data of the filed. Finally, according to the simulation results, some useful measures for preventing casing damage in Jibei oilfield was proposed.