scholarly journals The assessment of the tensile with torsion loading interaction using the selected hypotheses and the experiment

2019 ◽  
Vol 300 ◽  
pp. 16002
Author(s):  
Vladimír Chmelko ◽  
Pavol Novotný
Keyword(s):  
Fatigue Life ◽  
Material Properties ◽  
Life Time ◽  
Multiaxial Fatigue ◽  
The Individual ◽  
Stress Combinations

For two steels with different material properties (both cyclic and static ones) were experimentally obtained dependencies σa=f(Nf) and σa=f(Nf). The specimens of these materials were loaded with multiple tensile and torsion stress combinations. It was found out that the time-depending relationship between the individual stresses was proportional. The results for steel with high ration of Rm/Re are different comparing to the results of the second material. In this contribution, there will be confronted the experimentally obtained fatigue life-time magnitudes with selected multiaxial fatigue life-time hypotheses like Findley, McDiarmid, Dang-Van, Carpinteri-Spagnioli, and Margetin-Ďurka-Chmelko.

Transition piece design for an onshore hybrid wind turbine with multiaxial fatigue life estimation

2018 ◽  
Vol 42 (4) ◽  
pp. 286-303 ◽  
Author(s):  
Muhammad Farhan ◽  
Mohammad Reza Shah Mohammadi ◽  
José António Correia ◽  
Carlos Rebelo
Keyword(s):  
Fatigue Life ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Lattice Structure ◽  
Life Time ◽  
Multiaxial Fatigue ◽  
Analysis Tool ◽  
Cross Sectional ◽  
Onshore Wind ◽  
Transition Piece

Steel tubular structures are somewhat entrenched for the wind turbine towers. Recently, steel hybrid lattice/tubular towers are being investigated as a conceivable answer for taller onshore wind turbines for which convectional steel tubular towers are less competitive. Hybrid lattice/tubular towers require a transition piece which serves as a connection between lattice and tubular part. As the transition piece is supposed to transfer all the dynamic and self-weight loads to the lattice and foundation, these structural elements present unique features and are critical components to design and ought to resist strong cyclic bending moments, shear forces, and axial loads. Well-designed transition pieces with optimized ultimate state and fatigue capacities for manufacturing contribute to the structural soundness, reliability, and practicability of new onshore wind turbines hybrid towers. This research focuses on the investigation of the transition piece for an onshore wind turbine hybrid tower. The 5-MW reference wind turbine and a hybrid lattice/tubular tower were simulated in the servo-hydro aero-elastic analysis tool (by ASHES software) from which the loads and dynamic response of the supporting structure were obtained. Cross-sectional forces at the transition piece elevation were calculated and the connection with the lattice structure is designed. The transition piece was designed by finite element model considering ultimate limit load and fatigue load, using nonlinear analysis and multiaxial fatigue for life-time prediction, respectively. Multiaxial fatigue life was calculated based on Brown–Miller and Smith–Watson–Topper methods. In comparison, Smith–Watson–Topper method comes out to be more conservative. Potential of using high-strength steel S690 was investigated.

Influence of Wear Properties on Fretting Fatigue Life of a CK45 Alloy and the Al7175 Alloy

2008 ◽  
Vol 587-588 ◽  
pp. 971-975 ◽  
Author(s):  
M. Buciumeanu ◽  
A.S. Miranda ◽  
F.S. Silva
Keyword(s):  
Wear Resistance ◽  
Fatigue Life ◽  
Material Properties ◽  
Fatigue Behavior ◽  
Synergetic Effect ◽  
Fretting Fatigue ◽  
Reduction Factor ◽  
Strength Reduction ◽  
Strength Reduction Factor ◽  
Wear Properties

The main objective of this work was to study the influence of the wear properties of two commercial alloys (CK45 and Al7175) on their fretting fatigue behavior. It is verified the effect of material local degradation by wear on a fatigue strength reduction factor, namely the stress concentration factor, and on the overall fretting fatigue life of these materials. The fretting fatigue phenomenon is a synergetic effect between wear and fatigue. It is dependent on both the fatigue and the wear properties of the materials. Material properties promoting an increase in wear resistance should enhance fretting fatigue life.

Estimation of Fatigue Life for Hydraulic Excavator Boom under All Operating States

2011 ◽  
Vol 199-200 ◽  
pp. 463-469
Author(s):  
Qing Xin Ding ◽  
Ying Cheng Tian ◽  
Juan Chen ◽  
Jian Wen Chen ◽  
Kun Liang Hui ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Estimation Method ◽  
Maximum Principal Stress ◽  
Multiaxial Fatigue ◽  
Hydraulic Excavator ◽  
Dangerous Zone ◽  
Support Force ◽  
Contrast Analysis ◽  
History Of ◽  
Hinged Support

Fatigue is one of the most common failure mode in hydraulic excavator boom. To find the most fatigue dangerous operating state of boom and effectively improve the life of the structure, a new method is proposed for the estimation of fatigue life under all operation states. In the case of unknown the history of loading, firstly find out the hinged support force under all boom poses, then calculate the stress of every point of the boom under the actions of each group hinged support force via finite element method, and finally simulate all operating states through the poses combination, conducts analysis of multiaxial fatigue life in the maximum principal stress as the nominal stress, calculates the life and the most dangerous operating state in all points, and compares to obtain the most dangerous position and the life of the boom. The results of contrast analysis showed that: the most dangerous zone of the excavator boom calculated by the life estimation method of all operating states coincide with the actual destruction situation. The life of the structure can be greatly improved after a simple reasonable improvement of the parts.

scholarly journals Multiaxial fatigue study on steel transversal attachments under constant amplitude proportional and non-proportional loadings

2018 ◽  
Vol 165 ◽  
pp. 16007
Author(s):  
Martin Garcia ◽  
Claudio A. Pereira Baptista ◽  
Alain Nussbaumer
Keyword(s):  
Fatigue Life ◽  
High Strength ◽  
Fatigue Tests ◽  
Multiaxial Fatigue ◽  
Life Assessment ◽  
Experimental Program ◽  
Proportional Loading ◽  
Load Carrying ◽  
Stress States ◽  
Experimental Values

In this study, the multiaxial fatigue strength of full-scale transversal attachment is assessed and compared to original experimental results and others found in the literature. Mild strength S235JR steel is used and an exploratory investigation on the use of high strength S690QL steel and the effect of non-proportional loading is presented. The study focuses on non-load carrying fillet welds as commonly used in bridge design and more generally between main girders and struts. The experimental program includes 33 uniaxial and multiaxial fatigue tests and was partially carried out on a new multiaxial setup that allows proportional and non-proportional tests in a typical welded detail. The fatigue life is then compared with estimations obtained from local approaches with the help of 3D finite element models. The multiaxial fatigue life assessment with some of the well-known local approaches is shown to be suited to the analysis under multiaxial stress states. The accuracy of each models and approaches is compared to the experimental values considering all the previously cited parameters.

Sign in / Sign up

Export Citation Format

Share Document