scholarly journals SteBLife, a New Approach for the Accelerated Generation of Metallic Materials’ Fatigue Data

Metals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 798
Author(s):  
Ruth Acosta ◽  
Haoran Wu ◽  
Ramanan Sridaran Venkat ◽  
Fabian Weber ◽  
Jochen Tenkamp ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Deformation Behaviour ◽  
Fatigue Tests ◽  
Measurement Methods ◽  
Magnetic Field Measurement ◽  
Metallic Materials ◽  
Short Term ◽  
Technical Application ◽  
New Approach ◽  
Fatigue Data

The service life of materials and components exposed to repeated mechanical loads is limited, which is why the understanding of the damage evolution and estimating its fatigue life is of high importance for its technical application. This paper shows how temperature and magnetic field measurement methods can be used to describe the cyclic deformation behaviour of metallic materials and to derive parameters from this, which are used in short-term methods to calculate the fatigue life. Within the SteBLife (stepped-bar fatigue life) approach, only three to five fatigue tests with a stepped fatigue specimen are required to determine a complete S–N or Woehler curve with scatter bands for different failure probabilities. If only a trend S–N curve is required, the number of tests can be reduced to a single fatigue test only. In the framework of this paper, these approaches will be presented for normalised SAE 1045 (C45E) and quenched and tempered SAE 4140 (42CrMo4) steels.

Novel Methods for High-Cycle Fatigue Life Determination

2019 ◽  
Vol 810 ◽  
pp. 40-45
Author(s):  
Pavel Konopík ◽  
Radek Procházka ◽  
Martin Rund ◽  
Jan Džugan
Keyword(s):  
Fatigue Life ◽  
High Cycle Fatigue ◽  
Fatigue Tests ◽  
Cycle Fatigue ◽  
Testing Methods ◽  
Destructive Testing ◽  
New Approach ◽  
Constant Loading ◽  
Thermographic Analysis ◽  
Novel Methods

In the present paper, two novel methods for determining the fatigue limit are presented. Despite the fact that these methods are different in principle, both represent a new approach to testing where the main benefit is reduced consumption of material. The first method is based on small round specimens and can be considered as one of semi-destructive testing methods. The second method is based on infrared thermographic analysis and requires only one specimen. Results obtained with these techniques were compared with those obtained from standard high-cycle force-controlled fatigue tests under constant loading until failure.

The Effect of Manufacturing Defects on the Fatigue Behaviour of Ti-6Al-4V Specimens Fabricated Using Selective Laser Melting

2014 ◽  
Vol 891-892 ◽  
pp. 1519-1524 ◽  
Author(s):  
Qian Chu Liu ◽  
Joe Elambasseril ◽  
Shou Jin Sun ◽  
Martin Leary ◽  
Milan Brandt ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fatigue Life ◽  
Selective Laser Melting ◽  
Fatigue Crack Initiation ◽  
Fatigue Behaviour ◽  
Fatigue Tests ◽  
Metallic Materials ◽  
Laser Melting ◽  
Manufacturing Defects ◽  
Materials Properties

Additive Manufacturing (AM) technologies are considered revolutionary because they could fundamentally change the way products are designed. Selective Laser Melting (SLM) is a metal based AM process with significant and growing potential for the manufacture of aerospace components. Traditionally a material needs to be listed in the Metallic Materials Properties Development and Standardization (MMPDS) handbook if it is to be considered certified. However, this requires a considerable amount of test data to be generated on the materials mechanical properties. Therefore, the MMPDS certification process does not lend itself easily to the certification of AM components as the final component can have similar mechanical properties to wrought alloys combined with the defects associated with traditional casting and welding technologies. These defects can substantially decrease the fatigue life of a fabricated component. The primary purpose of this investigation was to study the fatigue behaviour of as-built Ti-6Al-4V (Ti64) samples. Fatigue tests were performed on the Ti-6Al-4V specimens built using SLM with a variety of layer thicknesses and build (vertical or horizontal) directions. Fractography revealed the presence of a range of manufacturing defects located at or near the surface of the specimens. The experimental results indicated that Lack-of-Fusion (LOF) defects were primarily responsible for fatigue crack initiation. The reduction in fatigue life appeared to be affected by the location, size and shape of the LOF defect.

Fatigue Modulus Concept and Life Prediction of Thick-Section S2-Glass/Vinylester Composites Under Flexural Loading

1999 ◽  
Author(s):  
Hassan Mahfuz ◽  
Kamruz Zaman ◽  
Anwarul Haque ◽  
Uday Vaidya ◽  
Hisham Mohamed ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Applied Stress ◽  
Life Prediction ◽  
Fatigue Tests ◽  
Fatigue Life Prediction ◽  
Analytical Prediction ◽  
Thick Section ◽  
Cycle Number ◽  
Material Constants ◽  
Fatigue Data

Abstract Fatigue life prediction of thick-section S2-Glass fiber reinforced Vinylester composites has been studied analytically using fatigue modulus concept. Flexural fatigue tests were conducted under three point bend configuration. A stress ratio of R = 0.1 and a frequency of 3 Hz has been used for the fatigue tests. Fatigue data have been generated at five load levels; 85%, 80%, 70%, 60% and 55% of the ultimate flexural strength. Using these fatigue data, S-N diagram has been generated. Fatigue modulus has been determined by the slope of the line drawn on a plot of applied stress vs. resultant strain at specific loading cycle. Since fatigue modulus degrades with cycle number, it was assumed that the degradation rate follows a power function of fatigue cycle. Using this concept, a practical and applicable equation for predicting fatigue life is established. The Fatigue Life Prediction method used in this investigation requires two distinct parameters, namely applied stress level and two material constants. These material constants have been determined from the fatigue test data. A comparison has been made between the analytical prediction and the experimentally obtained S-N curve. The correlation between the two has been observed to be excellent. Flexural failure modes have also been identified as extensive delamination, fiber fracture and fiber kinking. Microscopic observation shows that all failures are predominantly on the tensile side with slight fiber kinking and matrix crushing on the compression side.

A New Approach to the Evaluation of Fatigue Under Multiaxial Loadings

1981 ◽  
Vol 103 (2) ◽  
pp. 118-125 ◽  
Author(s):  
Y. S. Garud
Keyword(s):  
Fatigue Life ◽  
Constitutive Relations ◽  
Cyclic Stress ◽  
Fatigue Tests ◽  
Plastic Work ◽  
Strain Response ◽  
New Approach ◽  
Hardening Rule ◽  
Multiaxial Loadings ◽  
Good Agreement

A critical review of the methods for evaluating fatigue of metals under simple (proportional) and complex (nonproportional) loadings indicates that most of the criteria are expressed in terms of either stresses or strains. In this paper a new approach to the evaluation of fatigue under these loadings is proposed. This approach is based upon the idea of relating fatigue life to the plastic work during a cycle of the loading. A procedure is outlined for the calculation of plastic work which involves explicit considerations of the material constitutive relations. It is based on the structure of modern plasticity theories and a new “hardening rule.” Validity of the constitutive relations to predict the cyclic stress-strain response is demonstrated for out-of-phase multiaxial loadings. Available experimental results of fatigue tests under out-of-phase loadings are shown to be in good agreement with the predictions using the new approach.

scholarly journals Rolling-Element Fatigue Lives of Through-Hardened Bearing Materials

1972 ◽  
Vol 94 (2) ◽  
pp. 165-171 ◽  
Author(s):  
R. J. Parker ◽  
E. V. Zaretsky
Keyword(s):  
Fatigue Life ◽  
Weight Percent ◽  
Fatigue Tests ◽  
The Other ◽  
Ball Bearings ◽  
Outer Race ◽  
Aisi 52100 ◽  
Rolling Element ◽  
Fatigue Data ◽  
Bearing Materials

Rolling-element fatigue tests were run with eight through-hardened bearing materials at 150 deg F. One-half in. dia balls of each material were run in five-ball fatigue testers. Care was taken to maintain constant all variables known to affect rolling-element fatigue life. The longest lives at 150 deg F were obtained with AISI 52100. Ten-percent lives of the other materials ranged from 7 to 78 percent of that obtained with 52100. A trend is indicated toward decreased rolling-element fatigue life with increased total weight percent of alloying elements. Three groups of 120-mm bore ball bearings made from AISI M-1, AISI M-50, and WB-49 were fatigue tested at an outer-race temperature of 600 deg F. The 10-percent lives of the M-50 and M-1 bearings exceeded the calculated AFBMA life by factors of 13 and 6, respectively. The bearings with WB-49 races showed lives less than AFBMA life. The results of the bearing tests at 600 deg F correlate well with the results of the five-ball fatigue data at 150 deg F.

scholarly journals Experimental study on fatigue performance of Q420qD high-performance steel cross joint in complex environment

2021 ◽  
Author(s):  
Haigen Cheng ◽  
Cong Hu ◽  
Yong Jiang
Keyword(s):  
Fatigue Life ◽  
High Performance ◽  
Steel Structure ◽  
Steel Structures ◽  
Fatigue Tests ◽  
Fatigue Performance ◽  
Corrosive Media ◽  
Joint Connection ◽  
High Performance Steel ◽  
The Cross

AbstractThe steel structure under the action of alternating load for a long time is prone to fatigue failure and affects the safety of the engineering structure. For steel structures in complex environments such as corrosive media and fires, the remaining fatigue life is more difficult to predict theoretically. To this end, the article carried out fatigue tests on Q420qD high-performance steel cross joints under three different working conditions, established a 95% survival rate $$S{ - }N$$ S - N curves, and analyzed the effects of corrosive media and high fire temperatures on its fatigue performance. And refer to the current specifications to evaluate its fatigue performance. The results show that the fatigue performance of the cross joint connection is reduced under the influence of corrosive medium, and the fatigue performance of the cross joint connection is improved under the high temperature of fire. When the number of cycles is more than 200,000 times, the design curves of EN code, GBJ code, and GB code can better predict the fatigue life of cross joints without treatment, only corrosion treatment, and corrosion and fire treatment, and all have sufficient safety reserve.

scholarly journals Fatigue Testing of Wearable Sensing Technologies: Issues and Opportunities

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4070
Author(s):  
Andrea Karen Persons ◽  
John E. Ball ◽  
Charles Freeman ◽  
David M. Macias ◽  
Chartrisa LaShan Simpson ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Prediction Models ◽  
Fatigue Testing ◽  
Low Cycle Fatigue ◽  
Wearable Sensors ◽  
Fatigue Tests ◽  
Proof Of Concept ◽  
Cycle Fatigue ◽  
Wearable Sensing ◽  
Failure Data

Standards for the fatigue testing of wearable sensing technologies are lacking. The majority of published fatigue tests for wearable sensors are performed on proof-of-concept stretch sensors fabricated from a variety of materials. Due to their flexibility and stretchability, polymers are often used in the fabrication of wearable sensors. Other materials, including textiles, carbon nanotubes, graphene, and conductive metals or inks, may be used in conjunction with polymers to fabricate wearable sensors. Depending on the combination of the materials used, the fatigue behaviors of wearable sensors can vary. Additionally, fatigue testing methodologies for the sensors also vary, with most tests focusing only on the low-cycle fatigue (LCF) regime, and few sensors are cycled until failure or runout are achieved. Fatigue life predictions of wearable sensors are also lacking. These issues make direct comparisons of wearable sensors difficult. To facilitate direct comparisons of wearable sensors and to move proof-of-concept sensors from “bench to bedside,” fatigue testing standards should be established. Further, both high-cycle fatigue (HCF) and failure data are needed to determine the appropriateness in the use, modification, development, and validation of fatigue life prediction models and to further the understanding of how cracks initiate and propagate in wearable sensing technologies.

Sequential Optimization of an Emergency Response Vehicle’s Intra-Link Movement in a Partially Connected Vehicle Environment

2021 ◽  
pp. 036119812110179
Author(s):  
Gaby Joe Hannoun ◽  
Pamela Murray-Tuite ◽  
Kevin Heaslip ◽  
Thidapat Chantem
Keyword(s):  
Emergency Response ◽  
Lateral Position ◽  
Automated System ◽  
Sequential Optimization ◽  
Connected Vehicles ◽  
Linear Programs ◽  
Connected Vehicle ◽  
Market Penetration ◽  
Short Term ◽  
New Approach

This paper introduces a semi-automated system that facilitates emergency response vehicle (ERV) movement through a transportation link by providing instructions to downstream non-ERVs. The proposed system adapts to information from non-ERVs that are nearby and downstream of the ERV. As the ERV passes stopped non-ERVs, new non-ERVs are considered. The proposed system sequentially executes integer linear programs (ILPs) on transportation link segments with information transferred between optimizations to ensure ERV movement continuity. This paper extends a previously developed mathematical program that was limited to a single short segment. The new approach limits runtime overhead without sacrificing effectiveness and is more suitable to dynamic systems. It also accommodates partial market penetration of connected vehicles using a heuristic reservation approach, making the proposed system beneficial in the short-term future. The proposed system can also assign the ERV to a specific lateral position at the end of the link, a useful capability when next entering an intersection. Experiments were conducted to develop recommendations to reduce computation times without compromising efficiency. When compared with the current practice of moving to the nearest edge, the system reduces ERV travel time an average of 3.26 s per 0.1 mi and decreases vehicle interactions.

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