• Proceedings of the KSME Conference
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• 2000.11a
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• pp.304-309
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• 2000

Strain gage method is used to evaluate the mode I dynamic stress intensity factor of marging steel(18Ni) and titanium alloy(Ti-6A1-4V). To decide the best strain gage position on specimen, static fracture toughness test was performed. Then instrumented charpy impact test and dynamic tensile test was performed by using strain gage method for evlauating dynamic stress intensity factor. Strain gage signals on the crack tip region are used to calculate the stress intensity factors. It is found that strain gage method is more useful than method by using load which is obtained from impact tup to assess dynamic characteristics such as dynamic stress intensity factor.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1993.10a
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• pp.369-374
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• 1993

Measurements of strain near a crack tip with electrical resistance strain gages do not usually provide a reliable value of stress intensity factor (K sub I) because of local yielding and limited regions for strain-gage placement. This paper attempted to define a valid region and to indicate procedures for locating and orienting the strain-gage to determine stress intensity factor accurately from one stain-gage readings.

• IE interfaces
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• v.18 no.4
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• pp.444-453
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• 2005

The purpose of the Gage R&R study is to determine whether a measurement system is adequate for monitoring a process. If the measurement system variation is small relative to the process variation, then the measurement system is deemed "adequate". The sources of variation associated with the measurement system are compared using an analysis of variance (ANOVA) model, in general. A typical ANOVA model used in a standard Gage R&R study is the two-factor random effect model. Then, the ANOVA partitions the total variation into three categories: repeatability, reproducibility, part variation. However, if the process variation possesses the between group variation, within group variation, and within part variation, these variations can cause the measurement system evaluation to provide misleading results. That is, in the standard Gage R&R study these variations affect the estimate of repeatability, reproducibility, or both. This paper presents a four-factor nested factorial ANOVA model which explicitly considers these variations for the Gage R&R study. The variance component estimators are derived by setting the EMS equations equal to the corresponding mean square from the ANOVA table and solving. And the proposed model is compared with the standard Gage R&R model.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.8
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• pp.147-155
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• 1995

Recent experimental studies have been shown that strain gages can be employed to determine either static or dynamic stress intensity factors $K_{I}$ wiht relatively simple experiments. However, it does not usually provide a reliable value of stress intensity factor because of local yielding and limited regions for strain gage placement at the vicinity of the crack tip. This paper attempted to define a valid region and to indicate procedures for locating and orienting the strain gage to determine static toughness $K_{Is}$ accurately form one strain gage readings with respect to varying loadings. The strain gage methods was used for compact tension specimens made of Polycarbonate and PMMA(polymethyl methacrylate). Series expansions of the static and dynamic strain fields are applied. Strain gage orientation and location are then studied to optimize the strain response. Especially, in the dynamic experiment, the specimen employed is an oversized Charpy V-notch specimen which has been modified to provide significant constraint with a large elevation of the flow stress. The impact behavior of the specimen is monitored by placing strain gage near the crack tip. The dynamic toughness $K_{Id}$ is determined from the strain time traces of this gage.e.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2005.05a
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• pp.975-982
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• 2005

The purpose of the Gage R&R study is to determine whether a measurement system is adequate for monitoring a process. If the measurement system variation is small relative to the process variation, then the measurement system is deemed 'adequate'. The sources of variation associated with the measurement system are compared using an analysis of variance (ANOVA) model, in general. A typical ANOVA model used in a standard Gage R&R study is the two-factor random effect model. Then, the ANOVA partitions the total variation into three categories: repeatability, reproducibility, part variation. However, if the process variation possesses the between group variation, within group variation, and within-part variation, these variations can cause the measurement system evaluation to provide misleading results. That is, in the standard Gage R&R study these variations affect the estimate of repeatability, reproducibility, or both. This paper presents a four-factor nested factorial ANOVA model which explicitly considers these variations for the Gage R&R study. The variance component estimates are derived by setting the EMS equations equal to the corresponding mean square from the ANOVA table and solving. And the proposed model is compared with the standard Gage R&R model.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.9
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• pp.2205-2213
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• 1993

The characteristic test for gage factors of temperature self-compensated strain gages at cryogenic temperature is presented. By joining the international round robin test on electrical strain gages at cryogenic temperatures, the gage factors of three kinds of widely-used strain gages are obtained at the room temperature, the temperatures of liquid nitrogen and liquid helium. The calibration system which produce precise bending strain is by mechanical loading at cryogenic temperature. This paper also presents the creep characteristic of strain gages at maximum strain level.

• Journal of the Korean Society of Propulsion Engineers
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• v.4 no.1
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• pp.53-64
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• 2000

Strain gage method is investigated to evaluate the mode I stress intensity factor. Two types of specimens for CT and three point bend specimen are used. Sharp notch of specimens is manufactured by wiring discharge machining. Strain gages signal from the crack tip region are used to calculate stress intensity factors. The results are compared with those of the ASTM E399 method and finite element analysis. The present experimental results coincide well with the data obtained from finite element analysis. Attached position of strain gage should be seriously considered during the application of this method.

• Journal of Ocean Engineering and Technology
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• v.7 no.1
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• pp.124-132
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• 1993

In order to examine the effect of anisotropy and stress ratio on fatigue crack propagation rate and opening-closing behavior and also arrest behavior by single tension peak overload, the fatigue tests of constant amplitude atress and single tension peak overload adding to cycle of constant amplitude were carried out in stress ratio of -0.4, -0.2, and 0.4 with materials of T-L and L-T directions in 2024-T3 aluminum alloy plate. Crack opening-closing begavior were measured by the compliance method using COD gage and strain gage. In case of the crack opening-closing behavior was measured by strain gage, the effect of stress ratio is unchangeable. But in the case of COD gage, that is remarkably decreased. Fictitious effective stress intensity factor(U sub(f)) and effective stress intensity factor ratio(U) in L-T direction was higher than those in T-L direction and also threshold arrest overload ratio incrased as stress ratio decreased and that of T-L direction was higher than that in L-T direction.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1430-1433
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• 2003

Transducers, which are incorporated in control devices for fixed wing aircraft, land vehicles. and weapon systems were designed and manufactured by use of semiconductor strain gages. These transducers consist of three parts; flange mounts, sensing rods, and semiconductor strain gages. In this investigation, we designed cylindrical sensing rods with high sensitivity and developed installation procedures of semiconductor strain gages. The semiconductor strain gage has hish gage factor such that it can produce high resistance change in spite of low strain, but it is so small and fragile that one should handle carefully and sophisticated installation method is needed for good performances. The prototype transducers are manufactured, and then tested about three important factors: sensitivity, linearity, and hysteresis. We got results or 0.084 V/N sensitivity, 0.2% nonlinearity, and 0.5% hysteresis.

• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1529-1531
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• 2003

Thick film mechanical sensors can be categorized into four main areas piezoresistive, piezoelectric, piezocapastive and mechanic tube. In this areas, the thick film strain gage is the earliest example of a primary sensing element based on the substrates. The latest thick film sensor is used various pastes that have been specifically developed for pressure sensor application. The screen printing technique has been used to fabricate the pressure sensors on alumina substrate($Al_2O_3$). Thick film capacitive of strain sensing characteristics are reported and dielectric paste based on (Ti+Ba) materials. The electric property of dielectric paste has been studied and exhibit good properly with good gage factor comparable to piezoresistive strain gage. New piezocapacitive strain sensor was designed and tested. The output of capacitive value was good characteristics.