• Title, Summary, Keyword: Shot Size

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Dynamic numerical simulation of plastic deformation and residual stress in shot peening of aluminium alloy

  • Ullah, Himayat;Ullah, Baseer;Muhammad, Riaz
    • Structural Engineering and Mechanics
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    • v.63 no.1
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    • pp.1-9
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    • 2017
  • Shot peening is a cold surface treatment employed to induce residual stress field in a metallic component beneficial for increasing its fatigue strength. The experimental investigation of parameters involved in shot peening process is very complex as well as costly. The most attractive alternative is the explicit dynamics finite element (FE) analysis capable of determining the shot peening process parameters subject to the selection of a proper material's constitutive model and numerical technique. In this study, Ansys / LS-Dyna software was used to simulate the impact of steel shots of various sizes on an aluminium alloy plate described with strain rate dependent elasto-plastic material model. The impacts were carried out at various incident velocities. The influence of shot velocity and size on the plastic deformation, compressive residual stress and force-time response were investigated. The results exhibited that increasing the shot velocity and size resulted in an increase in plastic deformation of the aluminium target. However, a little effect of the shot velocity and size was observed on the magnitude of target's subsurface compressive residual stress. The obtained results were close to the published ones, and the numerical models demonstrated the capability of the method to capture the pattern of residual stress and plastic deformation observed experimentally in aluminium alloys. The study can be quite helpful in determining and selecting the optimal shot peening parameters to achieve specific level of plastic deformation and compressive residual stress in the aluminium alloy parts especially compressor blades.

Effect Analysis of Sample Size and Sampling Periods on Accuracy of Reliability Estimation Methods for One-shot Systems using Multiple Comparisons (다중비교를 이용한 샘플수와 샘플링 시점수의 원샷 시스템 신뢰도 추정방법 정확성에 대한 영향 분석)

  • Son, Young-Kap
    • Journal of the Korea Institute of Military Science and Technology
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    • v.15 no.4
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    • pp.435-441
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    • 2012
  • This paper provides simulation-based results of effect analysis of sample size and sampling periods on accuracy of reliability estimation methods using multiple comparisons with analysis of variance. Sum of squared errors in estimated reliability measures were evaluated through applying seven estimation methods for one-shot systems to simulated quantal-response data. Analysis of variance was implemented to investigate change in these errors according to variations of sample size and sampling periods for each estimation method, and then the effect analysis on accuracy in reliability estimation was performed using multiple comparisons based on sample size and sampling periods. An efficient way to allocate both sample size and sampling periods for reliability estimation tests of one-shot systems is proposed in this paper from the effect analysis results.

A Study of Economical Sample Size for Reliability Test of One-Shot Device with Bayesian Techniques (베이지안 기법을 적용한 일회성 장비의 경제적 시험 수량 연구)

  • Lee, Youn Ho;Lee, Kye Shin;Lee, Hak Jae;Kim, Sang Moon;Moon, Ki Sung
    • Journal of Applied Reliability
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    • v.14 no.3
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    • pp.162-168
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    • 2014
  • This paper discusses the application of Bayesian techniques with test data on similar products for performing the Economical Reliability Test of new one-shot device. Using the test data on similar products, reliability test required lower sample size currently being spent in order to demonstrate a target reliability with a specified confidence level. Furthermore, lower sample size reduces cost, time and various resources on reliability test. In this paper, we use similarity as calculating weight of similar products and analyze similarity between new and similar product for comparison of the essential function.

Residual stress Analysis of Inclined Shot Peening Using Finite Element Method (유한요소법을 이용한 경사쇼트피닝의 잔류응력 해석)

  • Baek, Seung;Yang, Won-Ho;Seok, Chang-Sung;Ryu, Meong-Hae
    • Proceedings of the KSME Conference
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    • pp.328-333
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    • 2003
  • The purpose of this study is to analyze the impact of shot peening angle on residual stress distribution. From the residual stress analysis of perpendicular shot peening, it could be known that the residual stress in the case of high velocity is larger than low velocity, but the amount of shot size has little effect on the magnitude of compressive residual stress. The centroidal residual stress is not greatly affected by the inclined shot peening but mainly related to the unstable conditions of surface residual stress field. Therefore, this tendency may lead to reduce fatigue life of treated material.

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Weibull Statistical Analysis According to Vickers Indentation Load of Peened ZrO2 Composites Ceramics by Different Shot Size (크기가 다른 Shot에 의하여 Peening한 ZrO2 복합 세라믹스의 비커스 압입하중에 따른 와이블 통계 해석)

  • Ahn, Seok Hwan;Kim, Dae Sik;Nam, Ki Woo
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.40 no.12
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    • pp.987-995
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    • 2016
  • In this study, the effects of shot peening (SP) on the Vickers hardness of $ZrO_2$ were studied. The size of the shot balls were ${\phi}180{\mu}m$ and ${\phi}300{\mu}m$. The Vickers hardness was measured using an indentation load of 98 N and 294 N. The Vickers hardness was evaluated using Weibull statistical analysis. The scale parameters were significantly evident from the indentation load of 98 N and the shot ball of ${\phi}180 {\mu}m$. Generally, the shape parameters were also evident from the small short ball (180sp). Thus, it is shown that the introduction of a compressive residual stress by SP is an effective technique for increasing the mechanical properties of $ZrO_2$.

FEM Analysis of Effect of Shot Peening for Stress Corrosion Cracking at Welded Part (용접부 응력부식균열 방지를 위한 쇼트피닝 효과의 유한요소 해석)

  • NAM KI-Woo;AHN SEOK-WHAN
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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    • pp.239-241
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    • 2004
  • Stress intensity factor of semi-circular crack front was calculated by FEM, and also allowable crack size which doesn‘t break out the fracture by SCC in residual stress field of STS materials. Allowable crack size was increased with compressive residual stress provided by shot peening on material surface, and with magnitude of compressive residual stress for depth direction.

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A Reliability Growth Prediction for a One-Shot System Using AMSAA Model (AMSAA 모델을 이용한 일회성 체계의 신뢰도성장 예측)

  • Kim, Myung Soo;Chung, Jae Woo;Lee, Jong Sin
    • Journal of Applied Reliability
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    • v.14 no.4
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    • pp.225-229
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    • 2014
  • A one-shot device is defined as a product, system, weapon, or equipment that can be used only once. After use, the device is destroyed or must undergo extensive rebuild. Determining the reliability of a one-shot device poses a unique challenge to the manufacturers and users due to the destructive nature and costs of the testing. This paper presents a reliability growth prediction for a one-shot system. It is assumed that 1) test duration is discrete(i.e. trials or rounds); 2) trials are statistically independent; 3) the number of failures for a given system configuration is distributed according to a binomial distribution; and 4) the cumulative expected number of failures through any sequence of configurations is given by AMSAA model. When the system development is represented by three configurations and the number of trials and failures during configurations are given, the AMSAA model parameters and reliability at configuration 3 are estimated by using a reliability growth analysis software. Further, if the reliability growth predictions do not meet the target reliability, the sample size of an additional test is determined for achieving the target reliability.

Bayesian Reliability Estimation for Small Sample-Sized One-shot Devices (작은 샘플 크기의 One-shot Devices를 위한 베이지안 신뢰도 추정)

  • Mun, Byeong Min;Sun, Eun Joo;Bae, Suk Joo
    • Journal of Applied Reliability
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    • v.13 no.2
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    • pp.99-107
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    • 2013
  • One-shot device is required to successfully perform its function only once at the moment of use. The reliability of a one-shot device should be expressed as a probability of success. In this paper, we propose a bayesian approach for estimating reliability of one-shot devices with small sample size. We employ a gamma prior to obtain the posterior distribution. Finally, we compare the accuracy of the proposed method with general maximum likelihood method.

Shot Type Detecting System using Face Detection (얼굴 검출을 이용한 숏 유형 감지 시스템)

  • Baek, Yeong-Tae;Park, Seung-Bo
    • Journal of the Korea Society of Computer and Information
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    • v.17 no.9
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    • pp.49-56
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    • 2012
  • In this paper, we propose the method that decides the shot types using face detection technique. The shot types, such as close-up shot, medium shot, and long shot, can be applied as useful information for understanding narrative structure of movies. The narrative structure of movie is builded by characters. Also their mental and emotional changes become inextricably bound up with them of narrative. The shot types are decided by distance between character and camera. If put together above them, shot types can be found by using detection technique of face size of characters and understand narrative of movie. To do this, we propose the methodology to detect shot type by face detecting and implement the system to do it. Additionally, we evaluate the performance of the system. The implementation system has been evaluated as 95% for close-up shot detection and 90% for medium shot detection, while 53.3% is just detected for long shots.

Effect of shot size in TV address on the elector's attitude (TV 연설에서 샷의 크기가 유권자의 태도에 미치는 영향)

  • Park, Dug-Chun
    • Journal of Digital Convergence
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    • v.10 no.3
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    • pp.283-290
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    • 2012
  • This study explored effect of shotsize and concern on the elector's attitude. For this study, 2 different styles of TV address moving pictures were produced on the basis of TV address text of district leader candidate. They were exposed to two different groups composed of university students, and the degree of favor, confidence and support was measured and analysed. The result of this study showed that the group exposed to bust shot was more favorable and supportive than the group exposed to waist shot. However, interaction effect between shot size and concern was not found. The meaning of this study can be found in the fact that effect of shot size as an element of non-verbal communication on the politician's image was proved through experiment.