scholarly journals The Effect of Technological Treatments and Loads on the Service Life of Fillet Welds

2020 ◽  
pp. 21-25
Author(s):  
Janusz Lewandowski ◽  
Dariusz Rozumek
Keyword(s):  
Service Life ◽  
Stress Ratio ◽  
Fatigue Cracks ◽  
Constant Stress ◽  
Fillet Welds ◽  
Test Results ◽  
Technological Treatment ◽  
Technological Treatments ◽  
Made In

The paper presents test results concerning the service life of fillet welds made in steel S355. In addition, the article discusses the initiation and growth of fatigue cracks in specimens subjected to bending with torsion. The tests were performed in relation to constant stress ratio R = -1 and 0. The results presented in the article take into account the effect of the technological treatment on the service life of the specimens. The tests revealed longer service life of the specimens not subjected to the technological treatment, both when R = -1 and 0.

Influence of Residual Stresses and of Mean Stress on the Fatigue Strength of Specimens with Longitudinal Non-Load-Carrying Fillet Welds

1970 ◽  
Vol 12 (6) ◽  
pp. 381-390
Author(s):  
T. R. Gurney
Keyword(s):  
Fatigue Strength ◽  
Residual Stresses ◽  
Stress Ratio ◽  
Fillet Welds ◽  
Direct Result ◽  
Mean Stress ◽  
Test Results ◽  
Load Carrying ◽  
Quantitative Explanation ◽  
Compressive Residual Stresses

Using results obtained in work on fatigue crack propagation in unwelded sheet specimens, an analysis has been made of fatigue test results for specimens with longitudinal non-load-carrying fillet welds tested in the as-welded and stress relieved conditions and also after treatment by local compression and by spot heating. It is shown that, by this means, it is possible to provide a quantitative explanation of the effect of residual stresses and applied stress ratio on fatigue strength, since all the results can be normalized on the basis of an effective stress range. In the course of the work it has been shown that the gross stress concentration factor for this type of joint is approximately 2·57. It has also again been demonstrated that the beneficial effect of spot heating on fatigue strength is a direct result of induced compressive residual stresses.

scholarly journals Test of fatigue crack growth in welded specimens subjected to bending

2018 ◽  
Vol 67 (1) ◽  
pp. 185-196
Author(s):  
Janusz Lewandowski ◽  
Dariusz Rozumek ◽  
Maria Hepner
Keyword(s):  
Heat Treatment ◽  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Welded Joints ◽  
Stress Ratio ◽  
Fatigue Cracks ◽  
Test Results ◽  
The Impact ◽  
Constant Moment

The paper presents the test results on the fatigue crack growth under cyclic bending specimens at constant moment amplitude made of S355 steel with fillet welds. Plane specimens with stress concentrators in form of the external two-sided blunt notches were tested. The tests were performed under constant value of the stress ratio R = –1 without and after heat treatment. The article also presents the test results of the microstructure of welded joints taking into account changes in the material after heat treatment and the impact of these changes on the fatigue life of specimens. Keywords: welded joints, fatigue cracks length, number of cycle, bending, microstructure

Mode I and Mode II Stress Intensity Factors Based on Crack Opening and Sliding Displacements

2011 ◽  
Vol 179-180 ◽  
pp. 1417-1422
Author(s):  
You Li Ma
Keyword(s):  
Stress Intensity ◽  
Stress Intensity Factors ◽  
Stress Ratio ◽  
Fatigue Cracks ◽  
Crack Opening ◽  
Intensity Factors ◽  
Slant Angle ◽  
Measured Stress ◽  
Discontinuous Displacement ◽  
Made In

It is necessary to study crack opening and sliding discontinuous displacement behavior under mixed-mode conditions because parts or structures of a machine with a crack maybe subject to stress from various directions. In this study ,therefore, using the cracks with different slant angle, which are made in circle stress of modeⅠwith stress ratio of R=0, the opening and sliding discontinuous displacements are measured ,so that modeⅠand mode Ⅱ stress intensity factors (KⅠ)mes and (KⅡ)mes at the crack tip are calculated. As a result, the measured stress intensity factors value of (KⅠ)mes from the fatigue crack with the slant angle β=60 deg. is smaller than the theoretical one (KⅠ). But for mode Ⅱ,(KⅡ)mes is about the same with (KⅡ). On the other hand, for the fatigue cracks with smaller slant angle β=45 deg.,(KⅡ)mes declined because of the crack-surface contact while (KⅠ)mes reduced.

Experimental Research on Influence of Loading Method on Dynamic Behavior of Recycled Concrete

2011 ◽  
Vol 199-200 ◽  
pp. 1171-1174 ◽  
Author(s):  
Xing Wen Luo ◽  
Hai Lin Yao
Keyword(s):  
Stress Ratio ◽  
Recycled Concrete ◽  
Loading Frequency ◽  
Test Results ◽  
Loading Method ◽  
Mechanics Characteristic ◽  
Loading Waveform ◽  
Loading Tests ◽  
Minimal Stress ◽  
Made In

The exploitation and application of recycled concrete are more and more extensive in latest years. But the research on the mechanics characteristic of recycle concrete under cyclic loading is very little. Six types of recycled concrete specimens were made in laboratory. After they were cured for a certain age, we have made a series of cycling loading tests on them. In the tests the maximum and minimal stress ratio, the loading frequency and loading waveform were all considered. The mechanics characteristic of recycled concrete under static loading and cyclic dynamic loading were contrasted. After analyzing the test results, we could get that the maximum stress and minimal stress ratio, the loading frequency and loading waveform influenced the unloading and loading modulus of recycled concrete directly in the tests, and the fatigue life of recycled concrete changed with the loading method.

scholarly journals An Experimental Study on the Effects of Compressive Stress on the Fatigue Crack Growth of Low-Alloy Steel

1994 ◽  
Vol 116 (3) ◽  
pp. 317-323
Author(s):  
D. P. Jones ◽  
R. G. Hoppe ◽  
J. L. Hechmer ◽  
B. A. James
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Stress Ratio ◽  
Fatigue Cracks ◽  
Ratio Test ◽  
Test Results ◽  
Stress Range ◽  
Low Alloy Steel ◽  
R Ratio

A series of fatigue crack growth rate tests was conducted in order to study the effects of negative stress ratio upon the fatigue crack growth rate of low-alloy steel in air environment. The tests used four-point bend specimens in order to simulate linear stress distributions typical of many pressure vessel applications. This type of testing adds to the knowledge on negative stress ratio effects for low-alloy steels that in the past have been obtained from uniform tension-compression tests. Additionally, the applied bending stress range was varied from low values of applied stress to high values of applied stress over twice the yield strength. Load control was used for tests for which the stress range was less than twice the yield strength and deflection control was used for the higher stress range tests. The crack geometries involved were both short and long fatigue cracks started at notches and tight fatigue cracks for which crack closure could occur over the full crack face. The results are presented in terms of the stress intensity factor ratio R = KMIN/KMAX. The negative R-ratio test results were correlated to an equation of the form da/dN = C[ΔK/(A−R)]n where A, C, and n are curve-fitting parameters. It was found that the effects of negative R-ratio on the fatigue crack growth rates for even the high stress range tests could be bounded by correlating the foregoing equation to only positive R-ratio test results and extending the resulting equation into the negative R-ratio regime.

scholarly journals Optimalisasi Umur Pemakaian AC Melalui Sistem Informasi Reminder Perawatan

2021 ◽  
Vol 5 (1) ◽  
pp. 118-127
Author(s):  
Aries Setiawan ◽  
◽  
Sasono Wibowo ◽  
Ida Farida ◽  
◽  
...  
Keyword(s):  
Information System ◽  
Service Life ◽  
Black Box ◽  
Air Conditioner ◽  
Test Results ◽  
Air Conditioners ◽  
Reminder System ◽  
Black Box Testing ◽  
Analysis Design ◽  
Made In

There is no periodic scheduling of Air Conditioner (AC) maintenance, which stems from the lack of recording on the maintenance card and maintenance book, resulting in a lot of AC damage that propagates from one component to component until finally the AC cannot function completely. A system is needed to provide information that will remind the time of maintenance as the first step in optimizing the life of the air conditioner. The purpose of this study is to build an information system of maintenance-reminder, so that the air conditioner used is maintained according to a predetermined schedule. The method used to build this system is a waterfall with five steps, namely: analysis, design, implementation, and testing. To Test the system that has been made, in this study using black box-testing by checking every part of each system. Our findings are to produce a standardized maintenance reminder system. The test results show that all components in the system are functioning properly, so it is easier for users to know which air conditioners need maintenance. With this system, it can maximize the maintenance function to optimize service life.

Fatigue Crack Growth in Specimens with Rectangular Section under Torsion and Bending with Torsion

2016 ◽  
Vol 250 ◽  
pp. 10-15 ◽  
Author(s):  
Sebastian Faszynka ◽  
Dariusz Rozumek
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Length ◽  
Crack Growth ◽  
Stress Ratio ◽  
Fatigue Cracks ◽  
Experimental Tests ◽  
Test Results ◽  
Constant Amplitude ◽  
Rectangular Section

The paper presents the test results on the fatigue crack growth under torsion and proportional bending with torsion in the aluminium alloy EN AW-2017A-T4. The tests were performed at the fatigue test stand MZGS-100 at the constant amplitude of moment MB = MT = MBT = 15.84 N⋅m and stress ratio R = -1. Plane specimens with stress concentrators in form of the external one-sided blunt notch were tested. The results of experiments were described on graphs of the fatigue crack length „a” versus numbers of cycles N. A non-uniform fatigue cracks growth on both lateral surfaces of specimens was observed during experimental tests.

scholarly journals Metallographic and Mechanical Research of the O–Ti2AlNb Alloy

Materials ◽  
2020 ◽  
Vol 13 (13) ◽  
pp. 3006
Author(s):  
Joanna Małecka ◽  
Dariusz Rozumek
Keyword(s):  
Room Temperature ◽  
Stress Ratio ◽  
Fatigue Cracks ◽  
Constant Load ◽  
Intermetallic Phases ◽  
Test Results ◽  
Notched Specimens ◽  
Ti2alnb Alloy ◽  
Initial Identification ◽  
Structural Tests

This paper provides the test results of the fatigue crack growth in notched specimens under tension. The tests were performed on plane specimens with external blunt two-sided notches at room temperature. The tested material was O–Ti2AlNb titanium alloy. The tests were carried out at constant load value and constant stress ratio R = 0. The tests were done at the fatigue stand Instron under the loading change frequency of 25 Hz. The results of mechanical and structural tests of the examined alloy were presented. Scanning electron microscopy (SEM) was used in metallography, which allowed for the initial identification of intermetallic phases. The development of fatigue cracks in the tested alloy indicates that there is a tendency for brittle fracturing, which ran along the grain boundary.

ЦИФРОВОЙ ИЗОЛЯТОР В СПЕЦИАЛИЗИРОВАННОМ КОРПУСЕ, ВЫПОЛНЕННОМ ПО ТЕХНОЛОГИИ LTCC

2020 ◽  
Vol 96 (3s) ◽  
pp. 392-395
Author(s):  
В.А. Бутузов ◽  
А.Е. Назаренко ◽  
Н.Ю. Дмитриев ◽  
В.А. Трофимов ◽  
В.А. Косевский ◽  
...  
Keyword(s):  
Low Temperature ◽  
Data Rate ◽  
Test Results ◽  
Made In

Представлены результаты разработки цифрового изолятора на основе интегрального микротрансформатора в специализированном корпусе, выполненном по технологии низкотемпературной совместно обжигаемой керамики (LTCC). Согласно результатам измерений тестовых образцов максимальная скорость передачи данных разработанного цифрового изолятора - не менее 30 Мбит/с. The paper presents the results of the development of a digital insulator based on an integral microtransformer in a specialized package made in technology of low-temperature co-fired ceramics. The isolator is a microassembly consisting of a transceiver chip and an integrated transformer. According to the test results, the maximum data rate speed of the developed digital insulator is not less than 30 Mbit/s.

Preparation Techniques and Property Evaluations of Highly Air Permeable Needle-Punched Geotextiles

2015 ◽  
Vol 749 ◽  
pp. 278-281
Author(s):  
Jia Horng Lin ◽  
Jing Chzi Hsieh ◽  
Jin Mao Chen ◽  
Wen Hao Hsing ◽  
Hsueh Jen Tan ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Service Life ◽  
Mechanical Strength ◽  
Pore Structure ◽  
Test Results ◽  
Needle Punching ◽  
Pet Fibers ◽  
Environmental Requirements ◽  
Preparation Techniques

Geotextiles are made of polymers, and their conjunction with different processes and materials can provide geotextiles with desirable characteristics and functions, such as filtration, separation, and drainage, and thereby meets the environmental requirements. Chemical resistant and mechanical strong polymers, including polyester (PET) and polypropylene (PP), are thus used to prolong the service life of the products made by such materials. This study proposes highly air permeable geotextiles that are made with different thicknesses and various needle punching speeds, and the influences of these two variables over the pore structure and mechanical properties are then examined. PET fibers, PP fibers, and recycled Kevlar fibers are blended, followed by being needle punched with differing spaces and speeds to form geotextiles with various thicknesses and porosities. The textiles are then evaluated for their mechanical strength and porosity. The test results show that a thickness of 4.5 cm and 1.5 cm demonstrate an influence on the tensile strength of the geotextiles, which is ascribed to the webs that are incompletely needle punched. However, the excessive needle punching speed corresponding to a thickness of 0.2 cm results in a decrease in tensile strength, but there is also an increase in the porosity of the geotextiles.

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