scholarly journals Fatigue test under cyclic loading useful for design against fatigue of cast machine elements (In case of crankcase cover made of AC4A-T6 and FC25)

1985 ◽  
Vol 34 (387) ◽  
pp. 1455-1459
Author(s):  
Hideto SUZUKI ◽  
Masaru OYABU ◽  
Tadashi UEKI ◽  
Takeshi KUNIO
Keyword(s):  
Cyclic Loading ◽  
Fatigue Test ◽  
Machine Elements ◽  
Cast Machine

Fatigue Performance of Concrete with Pre-Cracks in Tension-Compression Cycles

2014 ◽  
Vol 584-586 ◽  
pp. 1054-1061
Author(s):  
Jian Shen ◽  
Xiao Yun Liu ◽  
Lang Wu
Keyword(s):  
Fatigue Life ◽  
Fatigue Strength ◽  
Cyclic Loading ◽  
Fatigue Test ◽  
Stress Ratio ◽  
Fatigue Property ◽  
Fatigue Performance ◽  
Cycle Fatigue ◽  
Fatigue Load ◽  
Compression Cycle

A tension-compression cycle fatigue test was performed in order to study the fatigue property of C50 concrete with pre-cracks in cyclic loading. The stress ratio was-1 and the amplitude was 0.2 MPa ~1.30 MPa. The results show that the modified coefficient of fatigue strength is 0.198~0.265 and the infinite life fatigue strength is below 0.45MPa. While the log value of fatigue life is approximately linear with the amplitude of fatigue load stress, the discreteness of fatigue life, the particularity of concrete, has little to do with the amplitude. The S-N, P-N fatigue life curves and the constant fatigue life diagram of pre-crack concrete are obtained.

Statistical Analysis of Fatigue Test Data

2017 ◽  
Author(s):  
Carol Johnston
Keyword(s):  
Statistical Analysis ◽  
Fatigue Strength ◽  
Cyclic Loading ◽  
Fatigue Test ◽  
Test Data ◽  
Fatigue Tests ◽  
Fatigue Performance ◽  
Test Results ◽  
Girth Welds ◽  
New Procedures

The offshore environment contains many sources of cyclic loading. Standard design S-N curves, such as those in DNVGL-RP-C203, are usually assigned to ensure a particular design life can be achieved for a particular set of anticipated loading conditions. Girth welds are often the ‘weak link’ in terms of fatigue strength and so it is important to show that girth welds made using new procedures for new projects that are intended to be used in fatigue sensitive risers or flowlines do indeed have the required fatigue performance. Alternatively, designers of new subsea connectors, used for example in tendons for tension leg platforms, mooring applications or well-heads which will experience cyclic loading in service, also wish to verify the fatigue performance of their new designs. Often operators require contractors to carry out resonance fatigue tests on representative girth welds in order to show that girth welds made using new procedures qualify to the required design S-N curve. Operators and contractors must then interpret the results, which is not necessarily straightforward if the fatigue lives are lower than expected. Many factors influence a component’s fatigue strength so there is usually scatter in results obtained when a number of fatigue tests are carried out on real, production standard components. This scatter means that it is important first to carry out the right number of tests in order to obtain a reasonable understanding of the component’s fatigue strength, and then to interpret the fatigue test results properly. A working knowledge of statistics is necessary for both specifying the test programme and interpreting the test results and there is often confusion over various aspects of test specification and interpretation. This paper describes relevant statistical concepts in a way that is accessible to non-experts and that can be used, practically, by designers. The paper illustrates the statistical analysis of test data with examples of the ‘target life’ approach (that is now included in BS7608:2014 + A1) and the equivalent approach in DNVGL-RP-C203, which uses the stress modification factor. It gives practical examples to designers of a pragmatic method that can be used when specifying test programmes and interpreting the results obtained from tests carried out during qualification programmes, which for example, aim to determine whether girth welds made using a new procedure qualify to a particular design curve. It will help designers who are tasked with specifying test programmes to choose a reasonable number of test specimens and stress ranges, and to understand the outcome when results have been obtained.

Torsional Fatigue Test Applicable to Helical Spring Material Used in Candu Fuel Channel Spacers

2021 ◽  
Author(s):  
Andre Gagnon ◽  
Tejasvi Kashyap ◽  
Don Metzger
Keyword(s):  
Cyclic Loading ◽  
Fatigue Test ◽  
Cyclic Stress ◽  
Test System ◽  
Operating Conditions ◽  
Test Method ◽  
Rolling Motion ◽  
Helical Spring ◽  
Structural Components ◽  
Cycle Frequency

Abstract In a particular nuclear application, separation between structural components is maintained by a helical spring such that the separating load bears across the diameter of the spring coils. Relative motion between the structural components due to changing load and temperature is accommodated by rolling of the spring. This rolling motion while under radial load results in cyclic loading of the spring material. Fatigue analysis of the cyclic loading must take into consideration the material degradation due to the unique operating environment, so testing of ex-service material is required. Standard fatigue test specimens are not possible due to the small dimensions of the spring component. Cyclic stress may be applied to the material via a reciprocating rolling motion as per the operating conditions but this approach has practical limitations with respect to cycle frequency and uncertainty in stress response. A fatigue test system has been developed in which cyclic stress is achieved by applying torsional load with respect to the axis of the helical spring. This load translates into a pure bending state of stress in the cross-section of the coils. The relationship between applied load and stress is achieved analytically through curved beam analysis. Some practical considerations in the test setup are discussed along with supporting analysis, and results obtained with specimens taken from pre-service components are presented. The outcome of the tests is compared to applicable data and it is concluded that the test method is effective in producing valid fatigue data.

scholarly journals Implant-abutment screw removal torque values between customized titanium abutment, straight titanium abutment, and hybrid zirconia abutment after a million cyclic loading: an in vitro comparative study

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Disayut Klongbunjit ◽  
Weerapan Aunmeungtong ◽  
Pathawee Khongkhunthian
Keyword(s):  
Cyclic Loading ◽  
Fatigue Test ◽  
Bending Moment ◽  
In Vitro Study ◽  
Bending Moments ◽  
Static Compression ◽  
Removal Torque ◽  
Torque Values ◽  
Iso 14801

Abstract Purpose The aim of this study was to compare removal torque values after mechanical cyclic loading and bending moment after the static compression testing of customized titanium abutment compared with prefabricated and hybrid abutments. Materials and methods The study was developed according to ISO 14801:2016. Sixty implants were divided into three groups equally: Straight titanium abutment group, Customized titanium abutment group, and Hybrid zirconia abutment group. Abutments were fabricated with zirconia restoration. Forty five implants underwent for cyclic loading. The removal torque values were measured after a fatigue test was conducted at 0 cycles (control), 50,000 cycles and 1,000,000 cycles. In the second experiment, 15 implants were divided into the same groups. Then, bending moments were investigated. Results The mean initial removal torque value was significantly higher than 50,000 cycles and 1,000,000 cycles (P < 0.001). The comparison of mean removal torque value between types of abutments was not significantly different (P > 0.05), and the bending moments of all abutments were not significantly different (P > 0.05). Conclusions From the boundary of this in-vitro study, it could be concluded that customized titanium abutment and hybrid abutment were not significantly different in terms of removal torque values after the fatigue test. The bending moment between types of abutment were not significantly different. Thus, it could be concluded that abutment type does not significantly influence abutment stability or fracture strength.

Analysis of Fatigue Life in High Temperature of W Pattern Sealing Rings Used in Aircraft Engine

2014 ◽  
Vol 496-500 ◽  
pp. 571-574
Author(s):  
Xi Chen ◽  
Yun Wang
Keyword(s):  
Finite Element ◽  
High Temperature ◽  
Fatigue Life ◽  
Cyclic Loading ◽  
Fatigue Test ◽  
Aircraft Engine ◽  
Finite Element Models ◽  
Flight Safety ◽  
Sectional Structure ◽  
High Temperature Gas

sealing rings used in aircraft engine are surrounded by high-temperature gas and cyclic loading when they are working. The reliability of its work directly affect flight safety and engines life. This paper framed some kind of W pattern sealing rings finite element models with different sectional structure size, first analyze them strength of structure in specific conditions, then simulate the fatigue life of them by using analysis methods of fatigue and parameters of fatigue test, finally we can get damage contours and fatigue life in high temperature of W pattern sealing rings theoretically, providing some theoretical reference of designing and manufacturing sealing rings.

Comparative study of the effective parameters on residual stress relaxation in welded aluminum plates under cyclic loading

2020 ◽  
Vol 21 (5) ◽  
pp. 505
Author(s):  
Yousef Ghaderi Dehkordi ◽  
Ali Pourkamali Anaraki ◽  
Amir Reza Shahani
Keyword(s):  
Residual Stress ◽  
Cyclic Loading ◽  
Stress Relaxation ◽  
Stress Amplitude ◽  
Cyclic Plasticity ◽  
Mean Stress ◽  
Effective Parameters ◽  
Perfect Plasticity ◽  
Residual Stress Relaxation ◽  
Aluminum Plates

The prediction of residual stress relaxation is essential to assess the safety of welded components. This paper aims to study the influence of various effective parameters on residual stress relaxation under cyclic loading. In this regard, a 3D finite element modeling is performed to determine the residual stress in welded aluminum plates. The accuracy of this analysis is verified through experiment. To study the plasticity effect on stress relaxation, two plasticity models are implemented: perfect plasticity and combined isotropic-kinematic hardening. Hence, cyclic plasticity characterization of the material is specified by low cycle fatigue tests. It is found that the perfect plasticity leads to greater stress relaxation. In order to propose an accurate model to compute the residual stress relaxation, the Taguchi L18 array with four 3-level factors and one 6-level is employed. Using statistical analysis, the order of factors based on their effect on stress relaxation is determined as mean stress, stress amplitude, initial residual stress, and number of cycles. In addition, the stress relaxation increases with an increase in mean stress and stress amplitude.

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