• Title/Summary/Keyword: True Stress

Search Result 232, Processing Time 0.04 seconds

Deductive Argument and Inductive Argument (연역논증과 귀납논증)

  • Jeon, Jae-won
    • Journal of Korean Philosophical Society
    • /
    • v.141
    • /
    • pp.187-202
    • /
    • 2017
  • The aim of this paper is to clarify the difference between the concept of deduction-induction and Aristotle's concept of syllogismos-epagoge. First, Aristotle does not use the expression 'invalid syllogismos'. But a valid deduction is distinguished from a invalid deduction in modern logic. Second, from Aristotle's point of view syllogismos is paralleled by epagoge. Because syllogismos is equivalent to epagoge in logical form. But a disturbing lack of parallelism exists between deduction and induction by which the standards for establishing inductive conclusions are more demanding than those for deductive ones. Third, instructors in introductory logic courses ordinarily stress the need to evaluate arguments first in terms of the strength of the conclusion relative to the premises. Accordingly, students may be told to assume that premises are true. But Aristotle does not assume that premises are true. A syllogismos start from the conceptually true premise and a epagoge start from the empirically true premise.

Fracture Simulation of Low-Temperature High-Strength Steel (EH36) using User-Subroutine of Commercial Finite Element Code (상용 유한요소코드 사용자-서브루틴을 이용한 저온용 고장력강 (EH36)의 파단 시뮬레이션)

  • Choung, Joonmo;Nam, Woongshik;Kim, Younghun
    • Journal of Ocean Engineering and Technology
    • /
    • v.28 no.1
    • /
    • pp.34-46
    • /
    • 2014
  • This paper discusses a new formulation for the failure strain in the average stress triaxiaility domain for a low-temperature high-strength steel (EH36). The new formula available at a low average stress triaxiality zone is proposed based on the comparison of two results from tensile tests of flat type specimens and their numerical simulations. In order to confirm the validity of the failure strain formulation, a user-subroutine was developed using Abaqus/Explicit, which is known to be one of the most popular commercial finite element analysis codes. Numerical fracture simulations with the user-subroutine were conducted for all the tensile tests. A comparison of the engineering stress-strain curves and engineering failure strain obtained from the numerical simulation with the user-subroutine for the tensile tests revealed that the newly developed user-subroutine effectively predicts the initiation of failure.

Sodium nitroprusside mediates seedling development and attenuation of oxidative stresses in Chinese cabbage

  • Sung, Chang-Hyun;Hong, Jeum-Kyu
    • Plant Biotechnology Reports
    • /
    • v.4 no.4
    • /
    • pp.243-251
    • /
    • 2010
  • Nitric oxide (NO) has been shown to be involved in diverse physiological processes in microbes, animals and plants. In this study, the involvement of NO in the development and possible roles in oxidative stress protection of Chinese cabbage (Brassica rapa subsp. pekinensis cv. Samrack-ulgari) seedlings were investigated. Exogenous application of sodium nitroprusside (SNP) retarded root elongation, while increasing lateral root formation of Chinese cabbage. Plants showed no signs of external stress due to SNP application in true leaves. Cotyledons of 3-week-old Chinese cabbage plants were found to be highly sensitive to SNP application. Treated cotyledons displayed rapid tissue collapse and associated cell death. Although SNP application reduced root growth under normal growth conditions, it also enhanced methyl viologen (MV)-mediated oxidative stress tolerance. Analysis of SNP application to Chinese cabbage leaf disks, revealed SNP-induced tolerance against oxidative stresses by MV and $H_2O_2$, and evidence includes prevention of chlorophyll loss, superoxide anion (${O_2}^-$) accumulation and lipid peroxidation. This report supports a role for nitric oxide in modulating early seedling development, programmed cell death and stress tolerance in Chinese cabbage.

Investigation of the changes in texture of soybean sprout depending on the heating conditions in sous-vide and conventional hot water cooking (Sous-vide가열과 열탕가열 조건에 따른 콩나물 머리와 줄기의 조직감 변화에 관한 연구)

  • Lee, Yun Ju;Jung, Hwabin;Yoon, Won Byong
    • Journal of Applied Biological Chemistry
    • /
    • v.61 no.3
    • /
    • pp.219-226
    • /
    • 2018
  • The purpose of this study was to investigate the effect of thermal treatments, such as a sous-vide and a conventional hot water cooking, on the texture changes of soybean sprout. A novel method to measure texture properties of soybean sprout have been determined because of the irregular geometry of soybean sprout. The shape of cotyledon of bean spout was accurately analyzed using an image processing and a geometry model. To minimize the effect of the contact area on the texture measurement, a blade type of probe was selected for the measurement. True stress was evaluated to reflect the shape changes during deformation, and demonstrated that the measurement accurately distinguished the effect of thermal treatment on the texture. Different heating time (i.e., 0, 10, 20, and 30 min) was applied for both sous-vide and conventional cooking. Thermal processing caused hardening of textures for both cotyledon and hypocotyl of soybean sprout. The conventional cooking method showed higher stress values than those of sous-vide cooking. Sprouts cooked by sous-vide released the moisture after thermal processing while sprout cooked by a conventional water bath method could hold the moisture content during thermal processing. The soybean sprouts treated by conventional cooking method showed a higher score in sensory evaluation.

FINITE ELEMENT ANALYSIS OF STRESS DISTRIBUTION ACCORDING TO THE METHOD OF RESTORATION AFTER ROOT CANAL THERAPY (상악 소구치 근관치료후 수복방법에 따른 응력 분포의 유한 요소 분석)

  • Lee, Chung-Sik;Lee, Jae-Young;Cho, Hyo-Sun
    • Restorative Dentistry and Endodontics
    • /
    • v.21 no.1
    • /
    • pp.339-352
    • /
    • 1996
  • Many dentists have been taken an interest in restoration of severly damaged teeth after endodontic treatment and it is a true that there are lots of studies about it. In these days, although we have used Para-Post, pins, threaded steel post, cast gold post and core, and so on, as a method of restoration frequently, it has been in controversy with the effects of them on the teeth and surrounding periodontal tissue. In this study, we assume that the crown of the upper 1st premolar was severly damaged, and after the root canal therapy, two most common types of restoration were carried out ; 1) coronal-radicular amalgam restoration, 2) after setting up the Para-Post, restore with amalgam core and gold crown. After restoration, in order to present the concentration of stress at internal portion of the tooth and the surrounding periodontal tissue, we doveloped a 2-dimensional finite element model of labiopalatal section, then loaded forces from 2 long perpendicular to the lingual incline of buccal ridge an the middle point, parallel to the long direction axis of tooth at the fossa-were applied. The analyzed results were as follows : 1. Stress of the normal first premolar was concentrated on the most weakest anatomical structure, that is, cervical area, and no stress on the bifurcated area of the canal. 2. Crown restoration after root canal therapy causes large stress concentration on the bifurcated area of the canal. This stress concentration has larger value in case of lateral movement of mandible, and there are decrease in the stress concentration compared with natural tooth. 3. Coronal-radicular amalgam restoration method transports more stress to the tooth structure than restoration using Para-Post. 4. There are more stress concentration around Para-Post in the case of lateral movement, and we have more favo rable result when restored with Para-Post. 5. Generally, stress in the lateral movement is larger than stress in the perpendicular load.

  • PDF

Minimum Mean Squared Error Accelerated Life Test Plans for Exponential Lifetime Distribution

  • Joong Yang Park
    • Communications for Statistical Applications and Methods
    • /
    • v.2 no.2
    • /
    • pp.13-19
    • /
    • 1995
  • This paper considers model robust accelerated life test plans for estimating the logmean or percentile of product lige which is exponentially distributed. A linear relationship between the log mean life and the stress is assumed as usual, while the true relationship is quadratic. Optimum plans are then obtained by minimizing asymptotic mean squared error of maximum likelihood estimator of the log mean life.

  • PDF

Deformation Behaviour of Ti-8Ta-3Nb During Hot Forging

  • Lee Kyung Won;Ban Jae Sam;Kim Sun Jin;Cho Kyu Zong
    • Journal of Mechanical Science and Technology
    • /
    • v.20 no.1
    • /
    • pp.13-18
    • /
    • 2006
  • Ti-8Ta-3Nb, as a new biomaterial, was prepared by cast and swaging process. Their deformation behavior of Ti-8Ta-3Nb alloy has been characterized on the basis of its flow stress variation obtained from the true strain rate compression testing in the temperature of $700-900^{\circ}C$ and strain rate of $0.001-10\;s^{-1}$. At the strain rates lower than $0.1\;s^{-1}$ and the all temperature ranges which consist of two phase ${\alpha}+{\beta}$ as well as single ${\beta}$ phase fields, the flow curves show a small degree of flow softening behavior. In contrast, the shapes of the flow curves at other strain rates indicate unstable behavior. The shapes of the flow curves were similar in both as-cast and swaged specimen as well as in both ${\alpha}+{\beta}$ phase and ${\beta}$ phase. The flow stress data did not obey the kinetic rate equation over the entire regime of testing but a good fit has been obtained in the intermediate range of temperatures ($750-850^{\circ}C$). In this range, a stress exponent value of about 7.7 in as-cast specimens and about 6.2 in swaged specimens with an apparent activation energy of about 300 kJ/mol and about 206 kJ/mol respectively have been evaluated.

On Relevant Ramberg-Osgood Fit to Engineering Non-Linear Fracture Mechanics Analysis (정확한 비선형 파괴역학 해석을 위한 새로운 Ramberg-Osgood 상수 결정법)

  • Kim, Yun-Jae;Huh, Nam-Su;Kim, Young-Jin;Choi, Young-Hwan;Yang, Jun-Seok
    • Proceedings of the KSME Conference
    • /
    • 2003.04a
    • /
    • pp.170-177
    • /
    • 2003
  • This paper proposes a robust method for the Ramberg-Osgood (R-O) fit to accurately estimate elastic-plastic J from engineering fracture mechanics analysis based on deformation plasticity. The proposal is based on engineering stress-strain data to determine the R-O parameters, instead of true stress-strain data. Moreover, for practical applications, the method is given not only for the case when full stress-strain data are available but also for the case when only yield and tensile strengths are available. Reliability of the proposed method for the R-O fit is validated against detailed 3-D Finite Element (FE) analyses for circumferential through-wall cracked pipes under global bending using five different materials, three stainless steels and two ferritic steels. Taking the FE J results based on incremental plasticity using actual stress-strain data as reference, the FE J results based on deformation plasticity using various R-O fits are compared with reference J values. Comparisons show that the proposed R-O fit provides more accurate J values for all cases, compared to existing methods for the R-O fit. Advantages of the proposed R-O fit in practical applications are discussed, together with its accuracy.

  • PDF

Validation of a Local Failure Criteria Using the Results of Wall-Thinned Pipe Failure Tests (감육배관 손상시험 결과를 이용한 국부손상기준 검증)

  • Kim, Jin-Weon;Lee, Sung-Ho;Park, Chi-Yong
    • Transactions of the Korean Society of Mechanical Engineers A
    • /
    • v.33 no.12
    • /
    • pp.1393-1400
    • /
    • 2009
  • The objective of this study is to validate local failure criteria, which were proposed based on the notched-bar specimen tests combining with finite element (FE) simulations, using the results of real-scale pipe failure tests. This study conducted burst test using wall-thinned pipe specimens, which were made of 4 inch Sch.80 ASTM A106 Gr.B carbon steel pipe, under simple internal pressure at ambient temperature and performed associated FE simulations. Failure pressures were estimated by applying the failure criteria to the results of FE simulations and were compared with experimental failure pressures. It showed that the local stress based criterion, given as true ultimate tensile stress of material, accurately estimated the failure pressure of wall-thinned pipe specimens. However, the local strain based criterion, which is fracture strain of material as a function of stress tri-axiality, could not predict the failure pressure. It was confirmed that the local stress based criterion is reliably applicable to estimation of failure pressure of local wall-thinned piping components.

Modelling the rheological behaviour of fresh concrete: An elasto-viscoplastic finite element approach

  • Chidiac, S.E.;Habibbeigi, F.
    • Computers and Concrete
    • /
    • v.2 no.2
    • /
    • pp.97-110
    • /
    • 2005
  • Rheological behaviour of fresh concrete is an important factor in controlling concrete quality. It is recognized that the measurement of the slump is not a sufficient test method to adequately characterize the rheology of fresh concrete. To further understand the slump measurement and its relationship to the rheological properties, an elasto-viscoplastic, 2-D axisymmetric finite element (FE) model is developed. The FE model employs the Bingham material model to simulate the flow of a slump test. An experimental program is carried out using the Slump Rate Machine (SLRM_II) to evaluate the finite element simulation results. The simulated slump-versus-time curves are found to be in good agreement with the measured data. A sensitivity study is performed to evaluate the effects of yield stress, plastic viscosity and cone withdrawal rate on the measured flow curve using the FE model. The results demonstrate that the computed yield stress compares well with reported experimental data. The flow behaviour is shown to be influenced by the yield stress, plastic viscosity and the cone withdrawal rate. Further, it is found that the value of the apparent plastic viscosity is different from the true viscosity, with the difference depending on the cone withdrawal rate. It is also confirmed that the value of the final slump is most influenced by the yield stress.