CREEP AND FATIGUE PROPERTIES UNDER CYCLIC LOADING AT ELEVATED TEMPERATURES

1965 ◽  
pp. 5-48 ◽  
Author(s):  
B.J. LAZAN
Keyword(s):  
Cyclic Loading ◽  
Elevated Temperatures ◽  
Fatigue Properties

Isothermal Fatigue Behavior and Damage Modeling of a High Temperature Woven PMC

1999 ◽  
Vol 122 (1) ◽  
pp. 62-68 ◽  
Author(s):  
A. L. Gyekenyesi
Keyword(s):  
Compressive Strength ◽  
Elevated Temperature ◽  
Elevated Temperatures ◽  
Fatigue Behavior ◽  
Stiffness Degradation ◽  
Fatigue Properties ◽  
Residual Compressive Strength ◽  
Stiffness Reduction ◽  
Fatigue Damage Accumulation ◽  
Strength Tests

This study focuses on the fully reversed fatigue behavior exhibited by a carbon fiber/polyimide resin woven laminate at room and elevated temperatures. Nondestructive video edge view microscopy and destructive sectioning techniques were used to study the microscopic damage mechanisms that evolved. The elastic stiffness was monitored and recorded throughout the fatigue life of the coupon. In addition, residual compressive strength tests were conducted on fatigue coupons with various degrees of damage as quantified by stiffness reduction. Experimental results indicated that the monotonic tensile properties were only minimally influenced by temperature, while the monotonic compressive and fully reversed fatigue properties displayed greater reductions due to the elevated temperature. The stiffness degradation, as a function of cycles, consisted of three stages; a short-lived high degradation period, a constant degradation rate segment covering the majority of the life, and a final stage demonstrating an increasing rate of degradation up to failure. Concerning the residual compressive strength tests at room and elevated temperatures, the elevated temperature coupons appeared much more sensitive to damage. At elevated temperatures, coupons experienced a much larger loss in compressive strength when compared to room temperature coupons with equivalent damage. The fatigue damage accumulation law proposed for the model incorporates a scalar representation for damage, but admits a multiaxial, anisotropic evolutionary law. The model predicts the current damage (as quantified by residual stiffness) and remnant life of a composite that has undergone a known load at temperature. The damage/life model is dependent on the applied multiaxial stress state as well as temperature. Comparisons between the model and data showed good predictive capabilities concerning stiffness degradation and cycles to failure. [S0742-4795(00)01001-2]

scholarly journals Effects of thermomechanical history and environment on the fatigue behavior of (β)-Ti-Nb implant alloys

2018 ◽  
Vol 165 ◽  
pp. 06001 ◽  
Author(s):  
André Reck ◽  
Stefan Pilz ◽  
Ulrich Thormann ◽  
Volker Alt ◽  
Annett Gebert ◽  
...  
Keyword(s):  
Fatigue Strength ◽  
Cyclic Loading ◽  
Fatigue Behavior ◽  
Fatigue Tests ◽  
Grain Structure ◽  
Fatigue Properties ◽  
Β Phase ◽  
Α Phase ◽  
Nb Content ◽  
Implant Alloys

This study examined the fatigue properties of a newly developed cast and thermomechanical processed (β)-Ti-40Nb alloy for a possible application as biomedical alloy due to exceptional low Young’s modulus (64-73 GPa), high corrosion resistance and ductility (20-26%). Focusing on the influence of two microstructural states with fully recrystallized β-grain structure as well as an aged condition with nanometer-sized ω-precipitates, tension-compression fatigue tests (R=-1) were carried out under lab-air and showed significant differences depending on the β-phase stability under cyclic loading. Present ω- precipitates stabilized the β-phase against martensitic α’’ phase transformations leading to an increased fatigue limit of 288 MPa compared to the recrystallized state (225 MPa), where mechanical polishing and subsequent cyclic loading led to formation of α’’-phase due to the metastability of the β-phase. Additional studied commercially available (β)-Ti-45Nb alloy revealed slightly higher fatigue strength (300 MPa) and suggest a change in the dominating cyclic deformation mechanisms according to the sensitive dependence on the Nb-content. Further tests in simulated body fluid (SBF) at 37°C showed no decrease in fatigue strength due to the effect of corrosion and prove the excellent corrosion fatigue resistance of this alloy type under given test conditions.

scholarly journals Monotonic and Fatigue Properties of Steel Material Manufactured by Wire Arc Additive Manufacturing

2020 ◽  
Vol 10 (15) ◽  
pp. 5238 ◽  
Author(s):  
Michael Wächter ◽  
Marcel Leicher ◽  
Moritz Hupka ◽  
Chris Leistner ◽  
Lukas Masendorf ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Material Properties ◽  
Elevated Temperatures ◽  
Tensile Tests ◽  
Fatigue Properties ◽  
Practical Applications ◽  
Steel Material ◽  
Characteristic Values ◽  
The One ◽  
Wire Arc Additive Manufacturing

In this study, the monotonic and cyclic material properties of steel material of medium static strength produced additively in the wire arc additive manufacturing (WAAM) process were investigated. This investigated material is expected to be particularly applicable to the field of mechanical engineering, for which practical applications of the WAAM process are still pending and for which hardly any characteristic values can be found in the literature so far. The focus of the investigation was, on the one hand, to determine how the material characteristics are influenced by the load direction in relation to the layered structure and, on the other hand, how they are affected by different interlayer temperatures. For this purpose, monotonic tensile tests were carried out at room temperature as well as at elevated temperatures, and the cyclic material properties were determined. In addition, the hardness of the material and the residual stresses induced during production were measured and compared. In addition to the provision of characteristic properties for the investigated material, it was aimed to determine the extent to which the interlayer temperature influences the strength characteristics, since this can have a considerable influence on the production times and, thus, the economic efficiency of the process.

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