Nonlinear Behavior of Plain Woven G. F. R. P. Under Repeated Biaxial Tension/Torsion Loading

1991 ◽  
Vol 113 (4) ◽  
pp. 235-240 ◽  
Author(s):  
S. Amijima ◽  
T. Fujii ◽  
T. Sagami
Keyword(s):  
Shear Stress ◽  
Biaxial Tension ◽  
Stress Component ◽  
Nonlinear Behavior ◽  
Cyclic Stress ◽  
Fatigue Tests ◽  
Stress Profile ◽  
Stress Strain ◽  
Nonlinear Stress ◽  
S Curve

Fatigue tests on a plain woven glass composite at room temperature under biaxial (tension/torsion) loading were conducted. Nonlinear stress-strain (S-S) response especially in shear, was found and focused. Under pulsating shear stress loading, the S-S relation during loading periods became linear just before final failure, while the unloading S-S curve kept its nonlinear relation. According to the cyclic stress profile, the S-S curve was much affected and changed. It was found that preferential cracks due to the shear stress component occurred and might affect the fatigue failure as well as the nonlinear stress-strain response.

Temperature and Frequency Modified Fatigue Initiation Life of Solder Alloys Predicted by Endochronic Cyclic Damage-Coupled Viscoplasticity

2011 ◽  
Vol 27 (2) ◽  
pp. 267-277 ◽  
Author(s):  
C. F. Lee ◽  
S. I. Jeng ◽  
M. T. Liu
Keyword(s):  
Solder Alloy ◽  
Cyclic Stress ◽  
Fatigue Tests ◽  
Least Square ◽  
Strain Response ◽  
Stress Strain ◽  
Life Data ◽  
Form Equation ◽  
Fatigue Initiation ◽  
Cyclic Damage

ABSTRACTIn this paper, an evolution equation of cyclically internal damage in the intrinsic damage time scale after the threshold cycles N0 was extended by employing its damage parameters proposed to be dependent of frequency (v) and temperature (T) under cyclic fatigue loading. The resulting damage-coupled endochronic viscoplasticity can drive v and T modified power form equations of cyclic damage and its fatigue initiation life = N1 + N0. Under fatigue tests with T effect and N0 = 0, the power form equation of N1(T)/(Th), named as T-LCM (T modified Lee Coffin-Manson) equation for fatigue initiation life can bederived. The T modified factor (Th) depends on the T dependent material elastic modulus, the cyclicstress-strain response and the damage parameters. Theoretical predictions in the life data ofSn/3.8Ag/0.7Cu solder alloy under cyclic strain test with Tϵ [298,393] K were very well.Also under fatigue tests with v effect only, the power form equation of /v-LCM (v modified Lee-Coffin-Manson) equation for fatigue initiation life can be derived. The v modified parameter depends on the v dependent cyclic stress-strain response and the damage parameters. Theoreticalpredictions in the life data of 96.5Sn/3.5Ag solder alloy with surface cracking effect i.e. N0 ≠ 0 during cyclicstrain tests with v ϵ [0.001,1] Hz were quite well.Obviously, the values of power exponents C in the T-LCM and the v-LCM equations can not be determinedsimply by the least square method as in the Coffin-Manson empirical formulae. Also, they must bejustified by constrains imposed in the material parameters defining in the cyclic stress-strain response andthe accumulation behavior of cyclic damage.The resultant equations derived here and the Δ-LCM equation derived under Δ angle proportional cyclicstrain tests can be combined together to form a T-v-ΔLCM equation for fatigue life studies in the solderalloys using bulk specimens or BGA solider joint specimens.

The Maximum Stress in Optical Glass Fibers Under Two-Point Bending

2000 ◽  
Vol 123 (1) ◽  
pp. 70-73 ◽  
Author(s):  
Mikio Muraoka
Keyword(s):  
Axial Force ◽  
Maximum Stress ◽  
Optical Glass ◽  
Glass Fibers ◽  
Order Term ◽  
Nonlinear Behavior ◽  
Bending Stress ◽  
Stress Strain ◽  
Nonlinear Stress ◽  
Strain Relationship

The maximum stress in optical glass fibers subjected to two-point bending was evaluated by E. Suhir, “Effect of the Nonlinear Behavior of the Material on Two-Point Bending of Optical Glass Fibers,” ASME Journal of Electronic Packaging, Vol. 114, pp. 246–250, taking into account the shift in the neutral axis due to the nonlinear stress-strain relationship of the materials. However, the resulting distribution of bending stress on the fiber cross-section is not realistic because it produces a nonzero axial force. In the present study, we derive the correct formulas for evaluating the maximum stress under the valid condition that the bending stress does not contribute to the axial force. Moreover, we employ the nonlinear stress-strain relationship containing a third-order term of strain, which is more appropriate for the materials than that utilized by Suhir.

Cyclic Plastic Deformation of a Circular Plate With Work Hardening

1984 ◽  
Vol 106 (4) ◽  
pp. 336-341
Author(s):  
R. Winter
Keyword(s):  
Fatigue Life ◽  
Low Cycle Fatigue ◽  
Nonlinear Behavior ◽  
Strain Curve ◽  
Strain Range ◽  
Cyclic Strain ◽  
Cyclic Stress ◽  
Cycle Fatigue ◽  
Stress Strain ◽  
Element Analysis

An experimental and theoretical study was performed of the nonlinear behavior of a simply supported flat circular aluminum plate under reversed cyclic central load. The application is for the analysis of cyclic stress and strain of structural components in the plastic range for predicting low-cycle fatigue life. The main purpose was to determine the relative accuracy of an elastic-plastic large deformation finite element analysis when the material properties input data are derived from monotonic (noncyclic) stress-strain curves versus that derived from cyclic stress-strain curves. The results showed that large errors could be induced in the theoretical prediction of cyclic strain range when using the monotonic stress-strain curve, which could lead to large errors in predicting low-cycle fatigue life. The use of cyclic stress-strain curves, according to the model developed by Morrow, et al., proved to be accurate and convenient.

Axial and Diametral Cyclic Stress—Strain Response in Plain and Circumferentially Notched Cylindrical Bars at 550 °C

2006 ◽  
Vol 41 (4) ◽  
pp. 265-286 ◽  
Author(s):  
R. P Skelton ◽  
G. A Webster
Keyword(s):  
Low Cycle Fatigue ◽  
Notch Root ◽  
Hysteresis Loops ◽  
Cyclic Stress ◽  
Fatigue Tests ◽  
Gauge Length ◽  
Stress Strain ◽  
Deformation Response ◽  
Notched Specimens ◽  
Observed Behaviour

Cyclic stress-strain tests were undertaken at 550 °C on plain specimens and notched specimens of different notch acuities in several low- and high-alloy ferritic steels (1Cr-Mo-V, NF616, TB12M, and HCM12A). Integrated axial strains were measured between the minimum sections of the notches using a longitudinal extensometer, while surface hoop strains were measured by means of a diametral extensometer with probes located across the notch root. The same extensometry was employed in plain specimens. Over a period of 100 cycles, softening occurred in all plain specimens. These effects were also demonstrated in notched specimens in both axial and diametral directions, although to a lesser degree. From hysteresis loops determined in the notch tests, the cyclic deformation response of the notched regions was expressed in terms of an ‘equivalent gauge length’. Deviations from elastic-plastic behaviour in plain specimens were noted in that the commonly used ‘effective Poisson's ratiO' was greater than calculated. The effect was investigated further by exploring the characteristics of a very shallow notch, induced by straining a plain specimen to the onset of necking and beyond. The implications of observed behaviour in strain-control low-cycle fatigue tests is discussed.

scholarly journals Shape of the Cyclic Stress-Strain Loop in the Low-Cycle Fatigue Tests

1969 ◽  
Vol 12 (54) ◽  
pp. 1279-1284 ◽  
Author(s):  
Eiryo SHIRATORI ◽  
Yoichi OBATAYA
Keyword(s):  
Low Cycle Fatigue ◽  
Cyclic Stress ◽  
Fatigue Tests ◽  
Cycle Fatigue ◽  
Stress Strain

Improved Nonlinear Cyclic Stress–Strain Model for Reinforcing Bars Including Buckling Effect and Experimental Verification

2016 ◽  
Vol 16 (01) ◽  
pp. 1640005 ◽  
Author(s):  
Hong Yang ◽  
Yuntian Wu ◽  
Pengcheng Mo ◽  
Jinke Chen
Keyword(s):  
Nonlinear Behavior ◽  
Cyclic Stress ◽  
Cyclic Behavior ◽  
Reinforcing Bars ◽  
Stress Strain ◽  
Simulation Accuracy ◽  
Plastic Mechanism ◽  
Strain Relationship ◽  
Improved Accuracy ◽  
Strain Model

Buckling is an important nonlinear behavior of steel reinforcing bars subjected to repeated compression and tension strain reversals, which significantly affects the overall cyclic behavior of reinforced concrete (RC) elements and impairs their load-carrying and energy-dissipation capacities during strong earthquakes. The accuracy of numerical assessment of the seismic performance of RC elements can be much improved if the buckling effect is effectively included in the stress–strain model of reinforcing bars. In this paper, modified Gomes–Appleton cyclic steel stress–strain relationship intended for improved accuracy is presented, which is suitable for inclusion in programs based on Opensees platform for the nonlinear analysis of RC elements. The modification is developed to improve the simulation accuracy of the inelastic buckling stress–strain path by a simplified model based on the equilibrium of a plastic mechanism of buckled bar consisting of four plastic hinges. Then an adjustment coefficient is introduced to further modify the developed buckled bar stress–strain model. A comparison of the numerical simulated results with experimental results of 36 steel bars subjected to reversed tension-compression loading is performed to verify the accuracy and effectiveness of the proposed model.

Effect of the Nonlinear Behavior of the Material on Two-Point Bending of Optical Glass Fibers

1992 ◽  
Vol 114 (2) ◽  
pp. 246-250 ◽  
Author(s):  
E. Suhir
Keyword(s):  
Maximum Stress ◽  
Optical Glass ◽  
Glass Fibers ◽  
Nonlinear Behavior ◽  
High Strength ◽  
Large Strains ◽  
Stress Strain ◽  
Maximum Curvature ◽  
Nonlinear Stress ◽  
Strain Relationship

We evaluate the effect of the nonlinear stress-strain relationship on the maximum curvature and maximum stress in optical glass fibers subjected to two-point bending. The analysis uses an assumption that this relationship, obtained experimentally for the case of uniaxial tension (Mallinder and Proctor, 1964; Kraus, Testardi, and Thurston, 1979, Glaesemann, Gulati, and Helfinstine, 1988), holds in the case of compression as well, and is applicable also to bending deformations. We show that the shift in the neutral axis due to the nonlinear stress-strain relationship has a significant effect on the maximum stress, while its effect on the maximum curvature is small and need not be considered. We show also that this relationship, obtained for elastic strains, not exceeding 5 percent, cannot be applied for very large strains, and therefore the future experimental work should include the evaluation of the nonlinear behavior of the material, both in tension and compression, for higher strains and for high strength fibers (such as, for instance, fibers protected by metallic coatings). The obtained results can be helpful in the analysis of optical glass fibers subjected to two-point bending.

Cyclic Stress-Strain Behavior and Low-Cycle Fatigue of Ti 6-4 at 260°C

1992 ◽  
Vol 114 (4) ◽  
pp. 390-398 ◽  
Author(s):  
T. Bui-Quoc ◽  
R. Gomuc ◽  
A. Biron
Keyword(s):  
Strain Amplitude ◽  
Low Cycle Fatigue ◽  
Strain Curve ◽  
Cyclic Stress ◽  
Fatigue Tests ◽  
Cycle Fatigue ◽  
Stress Strain ◽  
Strain Behavior ◽  
Show Evidence ◽  
Strain Cycling

Low-cycle fatigue tests on Ti 6-4 (Ti-6Al-4V) have been carried out at 260°C under strain-controlled conditions with constant strain amplitude and increasing multistep strain levels. The results of constant strain amplitude tests were used to establish the fatigue diagram whereas the multistep tests were examined to assess the cyclic stress-strain behavior in comparison with the conventional stress-strain curve. Most of the tests were carried out under zero-to-tension conditions in the intermediatecycle range (Nf ≃ 3 x 103 to 105 cycles). The effect of prior strain cycling on the tensile properties was also investigated. The experimental data is discussed together with theoretical evaluations. In addition, microstructural examinations of the rupture surfaces have been made to show evidence on the type of crack initiation sites and on the crack propagation modes at different strain levels.

Stress-Strain Behavior of Inconel 718 During Low Cycle Fatigue

1982 ◽  
Vol 104 (3) ◽  
pp. 186-191 ◽  
Author(s):  
T. S. Cook
Keyword(s):  
Inconel 718 ◽  
Low Cycle Fatigue ◽  
Cyclic Stress ◽  
Fatigue Tests ◽  
Mean Stress ◽  
Cycle Fatigue ◽  
Stress Strain ◽  
Strain Behavior ◽  
Varied Temperature ◽  
The Mean

In the development of better methods of assessing damage accumulation, one of the requirements is an understanding of the cyclic constitutive behavior of the material. It is known that the cyclic stress-strain behavior is affected by temperature and possibly Rε ratio (εmin/εmax) and that the properties change as cycles are accumulated. This report presents some results, particularly the development of a mean stress in the material, obtained during low cycle fatigue tests of Inconel 718. The tests varied temperature and Rε ratio to determine their effects on the cyclic constitutive relation. Changes in the cyclic stress-strain behavior as a function of cycles were also examined. It was possible to relate the mean stress to either the total or plastic strain ranges for all temperatures. There was sufficient scatter in the data to prevent an unambiguous interpretation of the effect of Rε ratio on the mean stress, however.

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