An Energy-Based Axial Isothermal-Mechanical Lifing Procedure

2011 ◽  
Author(s):  
John Wertz ◽  
M.-H. Herman Shen ◽  
Onome Scott-Emuakpor ◽  
Tommy George ◽  
Charles Cross
Keyword(s):  
Strain Energy ◽  
Elevated Temperatures ◽  
Testing Procedure ◽  
Effect Of Temperature ◽  
Activation Temperature ◽  
Fatigue Process ◽  
Fracture Event ◽  
Operating Temperatures ◽  
Total Strain Energy Density

An energy-based fatigue lifing procedure for the determination of fatigue life and critical life of in-service structures subjected to axial isothermal-mechanical fatigue (IMF) has been developed. The foundation of this procedure is the energy-based axial room-temperature fatigue model, which states: the total strain energy density accumulated during both a monotonic fracture event and a fatigue process is the same material property. The energy-based axial IMF lifing framework is composed of the following entities: (1) the development of an axial IMF testing capability; (2) the creation of a testing procedure capable of assessing the strain energy accrued during both a monotonic fracture process and a fatigue process at various elevated temperatures; and (3), the incorporation of the effect of temperature into the axial fatigue lifing model. Both an axial IMF capability and a detailed testing procedure were created. The axial IMF capability was employed in conjunction with the monotonic fracture curve testing procedure to produce eight fracture curves at three operating temperatures. The strain energy densities for these fracture curves were compared, leading to the assumption of constant monotonic fracture energy at operating temperatures below the creep activation temperature.

An Energy-Based Axial Isothermal- Mechanical Fatigue Lifing Procedure

2011 ◽  
Vol 134 (2) ◽  
Author(s):  
John Wertz ◽  
M.-H. Herman Shen ◽  
Onome Scott-Emuakpor ◽  
Tommy George ◽  
Charles Cross
Keyword(s):  
Strain Energy ◽  
Elevated Temperatures ◽  
Testing Procedure ◽  
Effect Of Temperature ◽  
Activation Temperature ◽  
Fatigue Process ◽  
Mechanical Fatigue ◽  
Fracture Event ◽  
Operating Temperatures ◽  
Total Strain Energy Density

An energy-based fatigue lifing procedure for the determination of full-life and critical-life of in-service structures subjected to axial isothermal-mechanical fatigue (IMF) has been developed. The foundation of this procedure is the energy-based axial room-temperature fatigue model, which states: the total strain energy density accumulated during both a monotonic fracture event and a fatigue process is the same material property. The energy-based axial IMF lifing framework is composed of the following entities: (1) the development of an axial IMF testing capability; (2) the creation of a testing procedure capable of assessing the strain energy accrued during both a monotonic fracture process and a fatigue process at various elevated temperatures; and (3), the incorporation of the effect of temperature into the axial fatigue lifing model. Both an axial IMF capability and a detailed testing procedure were created. The axial IMF capability was employed in conjunction with the monotonic fracture curve testing procedure to produce fifteen fracture curves at four operating temperatures. The strain energy densities for these fracture curves were compared, leading to the assumption of constant monotonic fracture energy at operating temperatures below the creep activation temperature.

An Energy-Based Axial Isothermal-Mechanical Fatigue Lifing Method

2012 ◽  
Vol 134 (10) ◽  
Author(s):  
John Wertz ◽  
Todd Letcher ◽  
M.-H. Herman Shen ◽  
Onome Scott-Emuakpor ◽  
Tommy George ◽  
...  
Keyword(s):  
Strain Energy ◽  
Thermal Loading ◽  
Elevated Temperatures ◽  
Testing Procedure ◽  
Mechanical Fatigue ◽  
Full Life ◽  
Energy Dissipated ◽  
Life Predictions ◽  
Quasi Static Process

An energy-based fatigue lifing method for the determination of the full-life and critical-life of in-service structures subjected to axial isothermal-mechanical fatigue (IMF) has been developed. The foundation of this procedure is the energy-based axial room-temperature lifing model, which states: the total strain energy dissipated during both a quasi-static process and a dynamic (fatigue) process is the same material property. The axial IMF lifing framework is composed of the following entities: (1) the development of an axial IMF testing capability; (2) the creation of a testing procedure capable of assessing the strain energy dissipated during both a quasi-static process and a dynamic process at elevated temperatures; and (3) the incorporation of the effect of thermal loading into the axial fatigue lifing model. Both an axial IMF capability and a detailed testing procedure were created. The axial IMF capability was employed to produce full-life and critical-life predictions as functions of temperature, which were shown to have an excellent correlation with experimental fatigue data. For the highest operating temperature, the axial IMF full-life prediction was compared to lifing predictions made by both the universal slopes and the uniform material law prediction and was found to be more accurate at an elevated temperature.

An Energy-Based Axial Isothermal-Mechanical Fatigue Lifing Method

2012 ◽  
Author(s):  
John Wertz ◽  
Todd Letcher ◽  
M.-H. Herman Shen ◽  
Onome Scott-Emuakpor ◽  
Tommy George ◽  
...  
Keyword(s):  
Strain Energy ◽  
Thermal Loading ◽  
Elevated Temperatures ◽  
Testing Procedure ◽  
Mechanical Fatigue ◽  
Full Life ◽  
Energy Dissipated ◽  
Life Predictions ◽  
Quasi Static Process

An energy-based fatigue lifing method for the determination of the full-life and critical-life of in-service structures subjected to axial isothermal-mechanical fatigue (IMF) has been developed. The foundation of this procedure is the energy-based axial room-temperature lifing model, which states: the total strain energy dissipated during both a quasi-static process and a dynamic (fatigue) process is the same material property. The axial IMF lifing framework is composed of the following entities: (1) the development of an axial IMF testing capability; (2) the creation of a testing procedure capable of assessing the strain energy dissipated during both a quasi-static process and a dynamic process at elevated temperatures; and (3), the incorporation of the effect of thermal loading into the axial fatigue lifing model. Both an axial IMF capability and a detailed testing procedure were created. The axial IMF capability was employed to produce full-life and critical-life predictions as functions of temperature, which were shown to have excellent correlation with experimental fatigue data. For the highest operating temperature, the axial IMF full-life prediction was compared to lifing predictions made by both the Universal Slopes and the Uniform Material Law prediction and was found to be more accurate at elevated temperature.

50CrMo4 Steel-Determination of Mechanical Properties at Lowered and Elevated Temperatures, Creep Behavior, and Fracture Toughness Calculation

2010 ◽  
Vol 132 (2) ◽  
Author(s):  
J. Brnic ◽  
M. Canadija ◽  
G. Turkalj ◽  
D. Lanc
Keyword(s):  
Mechanical Properties ◽  
Elevated Temperatures ◽  
Tensile Tests ◽  
Effect Of Temperature ◽  
Uniaxial Tensile ◽  
Design And Manufacturing ◽  
Manufacturing Procedure ◽  
Short Time ◽  
Versus Strain

In this paper, some interesting, experimentally determined actualities referring to the 50CrMo4 steel are presented. That way, the mechanical properties of the material are derived from uniaxial tensile tests at lowered and elevated temperatures. Engineering stress versus strain diagrams for both mentioned temperatures, curves representing the effect of temperature on specimen elongation, and short-time creep curves are given. Notch impact energy test was also carried out. Taking into consideration the service life of the final product of the mentioned steel widely used in engine and machine technology, all of the mentioned data may be relevant during design and manufacturing procedure.

Experimental investigation on SFRC behaviour under elevated temperature

2017 ◽  
Vol 8 (3) ◽  
pp. 287-299 ◽  
Author(s):  
Vadims Goremikins ◽  
Lukas Blesak ◽  
Josef Novak ◽  
Frantisek Wald
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Elevated Temperatures ◽  
Bending Strength ◽  
Testing Procedure ◽  
Split Tensile Strength ◽  
Content Type ◽  
Steel Fibre Reinforced Concrete ◽  
Ultimate Bending Strength

Purpose This work aims to present an experimental study of steel fibre-reinforced concrete (SFRC) subjected to high temperature, especially focusing on residual behaviour. Design/methodology/approach Compressive strength and split tensile strength of SFRC cubes and ultimate bending strength of prisms were evaluated under ambient and elevated temperatures. The specimens were heated by ceramic heaters and then repacked for testing. Findings The results showed that a compressive strength of SFRC is reduced by 38 and 66 per cent, tensile strength is reduced by 25 and 59 per cent and ultimate bending force is reduced by 33 and 56 per cent in case of 400°C and 600°C, respectively, comparing with ambient temperature. Originality value The developed testing procedure could be used for determination of material properties of SFRC under elevated temperatures.

scholarly journals Research on the residual tensile strength of composite reinforcing bars exposed to elevated temperatures

2021 ◽  
Vol 1205 (1) ◽  
pp. 012011
Author(s):  
I Rozsypalova ◽  
J Prokes ◽  
Đ Cairović ◽  
F Girgle ◽  
P Danek ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Steady State ◽  
Analytical Approach ◽  
Elevated Temperatures ◽  
Reduction Rate ◽  
Testing Procedure ◽  
Reinforcing Bars ◽  
Gfrp Bars ◽  
Bar Diameter

Abstract Paper describes a testing procedure for the determination of tensile strength of the composite reinforcing bars subjected to elevated temperatures. Experimentally obtained results on GFRP bars with different diameter are presented and discussed. Moreover, a brief comparison with an analytical approach was included. Almost identical temperature reduction rate of tensile strength was observed for all tested specimens, regardless diameter of the bar. Therefore, it can be expected, that different bar diameter should not significantly affect the results especially if steady state conditions were assumed.

Effect of Temperature, Velocity Gradient and I.V. Heparin on in Vitro Blood Coagulation and Platelet Aggregation

1967 ◽  
Vol 17 (01/02) ◽  
pp. 112-119 ◽  
Author(s):  
L Dintenfass ◽  
M. C Rozenberg
Keyword(s):  
Blood Coagulation ◽  
Velocity Gradient ◽  
Elevated Temperatures ◽  
Morphological Changes ◽  
Effect Of Temperature ◽  
Clotting Time ◽  
Progressive Change ◽  
Aggregation Of Platelets ◽  
Microscopic Techniques

SummaryA study of blood coagulation was carried out by observing changes in the blood viscosity of blood coagulating in the cone-in-cone viscometer. The clots were investigated by microscopic techniques.Immediately after blood is obtained by venepuncture, viscosity of blood remains constant for a certain “latent” period. The duration of this period depends not only on the intrinsic properties of the blood sample, but also on temperature and rate of shear used during blood storage. An increase of temperature decreases the clotting time ; also, an increase in the rate of shear decreases the clotting time.It is confirmed that morphological changes take place in blood coagula as a function of the velocity gradient at which such coagulation takes place. There is a progressive change from the red clot to white thrombus as the rates of shear increase. Aggregation of platelets increases as the rate of shear increases.This pattern is maintained with changes of temperature, although aggregation of platelets appears to be increased at elevated temperatures.Intravenously added heparin affects the clotting time and the aggregation of platelets in in vitro coagulation.

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