scholarly journals Effect of Cyclic Loading on the Creep Performance of Silicon Nitride

1996 ◽  
Vol 118 (2) ◽  
pp. 251-256 ◽  
Author(s):  
A. A. Wereszczak ◽  
M. K. Ferber ◽  
T. P. Kirkland ◽  
C.-K. J. Lin
Keyword(s):  
Silicon Nitride ◽  
Plastic Strain ◽  
Creep Strain ◽  
Strain Relaxation ◽  
Cyclic Creep ◽  
Cyclic Fatigue ◽  
Fatigue Tests ◽  
Dominant Component ◽  
Static Creep ◽  
Stressing Rate

Tension–tension cyclic fatigue tests (triangular waveform, σmax = 100 MPa, R = 0.1) were conducted on hot isostatically pressed (HIPed) silicon nitride at frequencies spanning several orders of magnitude (5.6 × 10−6 to 0.1 Hz or 10−3 MPa/s to 18 MPa/s) at 1370°C in air. The amount of cyclic creep strain was found to be a function of the frequency or stressing rate, with greater strains to failure observed as the frequency or stressing rate decreased. The total strain was viewed as the sum of elastic, anelastic (or transient recoverable), and plastic (viscous or nonrecoverable) strain contributions, after the empirical Pao and Marin model. The plastic strain was found to be the dominant component of the total creep and was unsatisfactorily represented by the Pao and Marin model. To circumvent this, a time exponent was introduced in the plastic strain term in the Pao and Marin model. This modification resulted in good correlation between model and experiment at the slower frequencies examined but overpredicted the cyclic creep strain at the faster frequencies. The utility of using the modified Pao and Marin model to predict cyclic creep response from static creep and strain relaxation tests is described.

scholarly journals Effect of Cyclic Loading on the Creep Performance of Silicon Nitride

1995 ◽  
Author(s):  
Andrew A. Wereszczak ◽  
Mattison K. Ferber ◽  
Timothy P. Kirkland ◽  
Chih-Kuang J. Lin
Keyword(s):  
Silicon Nitride ◽  
Plastic Strain ◽  
Creep Strain ◽  
Strain Relaxation ◽  
Cyclic Creep ◽  
Cyclic Fatigue ◽  
Fatigue Tests ◽  
Recoverable Strain ◽  
Dominant Component ◽  
Stressing Rate

Tension-tension cyclic fatigue tests (triangular waveform, σmax = 100 MPa, R = 0.1) were conducted on hot isostatically pressed (HIPed) silicon nitride at frequencies spanning several orders of magnitude (5.6×10−6 to 0.1 Hz or 10−3 MPa/s to 18 MPa/s) at 1370°C in air. The amount of cyclic creep strain was found to be a function of the frequency or stressing rate with greater strains to failure observed as the frequency or stressing rate decreased. The total strain was viewed as the sum of elastic, anelastic (or transient recoverable), and plastic (viscous or non-recoverable) strain contributions, after the empirical Pao and Marin model. The plastic strain was found to be the dominant component of the total creep and was unsatisfactorily represented by the Pao and Marin model. To circumvent this, a time exponent was introduced in the plastic strain term in the Pao and Marin model. This modification resulted in good correlation between model and experiment at the slower frequencies examined but over-predicted the cyclic creep strain at the faster frequencies. The utility of using the modified Pao and Marin model to predict cyclic creep response from static creep and strain relaxation tests is described.

High Temperature Fatigue Properties of Silicon Nitride in Nitrogen Atmosphere

1992 ◽  
Vol 287 ◽  
Author(s):  
Yasuhiro Shigegaki ◽  
Takashi Inamura ◽  
Akihiko Suzuki ◽  
Tadashi Sasa
Keyword(s):  
Silicon Nitride ◽  
Fatigue Behavior ◽  
Cyclic Fatigue ◽  
Nitrogen Atmosphere ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Static Fatigue ◽  
Four Point Bending ◽  
Bending Mode ◽  
Sintered Silicon

ABSTRACTCyclic and static fatigue properties of pressure-less sintered silicon nitride were evaluated at 1000° C in air and in nitrogen using four-point bending mode. The data of cyclic fatigue tests or static fatigue tests and the morphology of the fractured surfaces in nitrogen were compared with those in air. The cyclic fatigue behavior was remarkably influenced by the atmosphere, while the static fatigue was less influenced. Crack healing effect due to the oxidation around the crack are thought to be the most probable mechanism to affect the cyclic fatigue rate in air.

An approach to the determination of cyclic creep strain

1979 ◽  
Vol 11 (11) ◽  
pp. 1225-1229 ◽  
Author(s):  
V. P. Golub
Keyword(s):  
Creep Strain ◽  
Cyclic Creep

Damage in Adhesive Joints During Low Cycle Fatigue

2010 ◽  
Author(s):  
Iva´n C. Ca´bulo-Pe´rez ◽  
Juan P. Casas-Rodri´guez
Keyword(s):  
Plastic Strain ◽  
Low Cycle Fatigue ◽  
Stress Test ◽  
Damage Model ◽  
Fatigue Tests ◽  
Constant Stress ◽  
Cycle Fatigue ◽  
Damage Behavior ◽  
Non Linear ◽  
Compressive Loads

The objective of this research is to study the damage behavior of bulk adhesive and single lap joint (SLJ) specimens during low cycle fatigue (LCF). Fatigue tests under constant stress amplitude were done and strain response was measured through cycles to failure using the bulk adhesive and SLJ data. A non linear damage model was used to fit experimental results. Identification of the damage parameters for bulk adhesive was obtained from the damage against accumulated plastic strain plot. It is shown that the plastic strain can be obtained from the constant stress test if the instantaneous elastic modulus, i.e. modulus affected by damage, is evaluated for each cycle. On the other hand, damage in SLJ was seen mainly in the adhesive for itself — no substrate failure — this fact is used to propose that fatigue response in the joint is due to continuum damage accumulation in the adhesive as the number of cycles increases. Damage behavior under compressive loads was not taken into account but good correlation of numerical and experimental data was obtained. It was found that damage evolution behaves in a non linear manner as the plastic deformation grows for each cycle: on fatigue onset an accelerated damage grow is observed, then a proportional evolution, and finally a rapid failure occurs; this characteristics were seen in both the SLJ and bulk adhesive specimen. So far, this research takes the damage model found in a standard adhesive specimen and assumes it is accurate enough to represent the damage behavior of the SLJ configuration.

scholarly journals FATIGUE TESTS OF METAL MATERIALS (review) Part 1. Main definitions, loading parameters, representation of results of tests

2020 ◽  
pp. 59-70
Author(s):  
V.S. Erasov ◽  
◽  
E.I. Oreshko ◽  
Keyword(s):  
Hysteresis Loop ◽  
Distinctive Feature ◽  
Main Crack ◽  
Elastoplastic Deformation ◽  
Cyclic Fatigue ◽  
Fatigue Tests ◽  
Surface Layers ◽  
Near Surface ◽  
Mechanical Hysteresis ◽  
Metal Materials

The article gives the review of techniques of fatigue tests of metal materials and presents the results of such tests . It has been shown that the low-cyclic fatigue occurs in conditions of elastoplastic deformation in material microvolume from the first cycles of loading. Its distinctive feature is influence on durability of the size and form of a mechanical hysteresis loop . Nucleation of fatigue microcracks and formation of the main crack occurs on the surface and in near-surface layers of a sample.

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