Strain Sweep Fatigue Testing of Sand Asphalt Mortar to Investigate the Effects of Sample Geometry, Binder Film Thickness, and Testing Temperature

2021 ◽  
pp. 036119812110116
Author(s):  
Lilian Ribeiro de Rezende ◽  
Santosh Reddy Kommidi ◽  
Yong-Rak Kim ◽  
Mahdieh Khedmati
Keyword(s):  
Film Thickness ◽  
Fatigue Testing ◽  
Fatigue Behavior ◽  
Viscoelastic Behavior ◽  
Testing Temperature ◽  
Test Results ◽  
Study Results ◽  
Linear Viscoelastic Behavior ◽  
Strain Sweep ◽  
Asphalt Mortar

This study evaluated the viscoelastic fatigue behavior of binder using strain sweep fatigue testing of cylindrical sand asphalt mortar (SAM) samples. The SAM samples can represent the realistic film thickness (such as 10–70 μm thick) of the binder in mixtures, while testing repeatability-efficiency can still be met as a result of the use of a standard sand as a load carrier between binder films. A proper testing protocol is still under development, and one of the unknowns in the field is a set of testing conditions that can provide repeatable and case-sensitive test results. Toward that end, SAM samples with different dosages of binder in three geometries were tested at varying temperatures in this study. A PG 64-34 binder was used, and a strain sweep test using a dynamic shear rheometer was conducted to compare the test results from the different cases. Four parameters resulting from the SAM testing were examined: two accounting for material linear viscoelastic behavior and two accounting for fatigue damage characteristics. The parameters were incorporated with statistical analyses to quantitatively evaluate data variability and sensitivity influenced by the binder film thickness, SAM specimen geometry, and testing temperature. The coefficient of variation was less than 20% for all the cases, which indicated the validity of the SAM method attempted in this study. Results also indicated that fatigue behavior was independent of the SAM geometries used in this study, while binder film thickness and testing temperature significantly affected test results.

An Overview of the Fatigue of Polychloroprene Rubber

2014 ◽  
Vol 891-892 ◽  
pp. 518-523
Author(s):  
Jean Louis Poisson ◽  
Florian Lacroix ◽  
Stéphane Méo ◽  
Gaelle Berton ◽  
Narayanaswami Ranganathan
Keyword(s):  
Fatigue Behavior ◽  
Viscoelastic Behavior ◽  
Fatigue Tests ◽  
Test Results ◽  
Biaxial Fatigue ◽  
Synthetic Rubber ◽  
Strain Induced Crystallization ◽  
Life Enhancement ◽  
Induced Crystallization

Some fundamental studies carried in a synthetic rubber - Chloroprene CR29 are presented in the first part of the paper. A critical analysis of test results, shows that an energy based approach permits the determination of fatigue lives in this material. This aspect is further enhanced by biaxial fatigue tests in the same material. These tests covering a life range from 10000 to 1000000 cycles show that the energy based model is very efficient to describe the fatigue behavior. Some evidence of strain induced crystallization (previously observed in natural rubber) with associated life enhancement at high load ratios is also presented. A comprehensive model based on the determination of the constitutive laws taking into account the viscoelastic behavior is developed showing excellent correlation with experimental data.

Study on Rheological Characterization of Uncured Natural Rubber with Different Initial Moisture Contents Dried by Microwave

2014 ◽  
Vol 998-999 ◽  
pp. 383-386
Author(s):  
Fu Quan Zhang ◽  
Yong Zhou Wang ◽  
Mei Chen ◽  
Mao Fang Huang ◽  
Ri Zhong Zeng
Keyword(s):  
Natural Rubber ◽  
Viscoelastic Behavior ◽  
Sweep Frequency ◽  
Rheological Characterization ◽  
Moisture Contents ◽  
Linear Viscoelastic Behavior ◽  
Linear Viscoelastic ◽  
Strain Sweep ◽  
Viscous Torque

In this work, the rheological behavior of uncured natural rubber with different initial moisture contents dried by microwave was studied using RPA under frequency sweep and strain sweep modes. It can be seen from the results that the variation trend of viscous torque S`` versus sweep frequency kept with the trend of elastic torque S` versus sweep frequency. Moreover, the viscous torque S`` values were lower than those for elastic torque S`, a good linear relation curve was obtained by plotting elastic torque S` versus sweep frequency. The curve of storage shear modulus G` versus sweep strain presented a linear relationship, showed a linear viscoelastic behavior of uncured natural rubber with different initial moisture contents. This may be explained by the degradation of molecular chains of natural rubber and the van der waals forces between them.

Low-Cycle Fatigue Testing of a Novel Aluminum Alloy Buckling-Restrained Brace

2016 ◽  
Vol 710 ◽  
pp. 345-350 ◽  
Author(s):  
Ye Liu ◽  
Li Zhou ◽  
Chun Lin Wang
Keyword(s):  
Aluminum Alloy ◽  
Inner Core ◽  
Fatigue Testing ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Hysteretic Behavior ◽  
Test Results ◽  
Cycle Fatigue ◽  
Buckling Restrained Brace ◽  
Design Variables

Compared with steel buckling-restrained braces, aluminum alloy BRBs show excellent advantages in structures where severe corrosion effects can be expected. At the same time, in order to avoid the effect of welding discussed in the previous research, a novel Aluminum alloy Bamboo-shaped Buckling-Restrained Brace (AL-BBRB) consisting of a bamboo-shaped inner core and an outer hollow circular tube was proposed and tested herein. Parametric studies with design variables including cross-sectional sizes of slubs and length of segments were conducted. A series of low-cycle fatigue tests, containing 4 specimens, were performed to address the low-cycle fatigue behavior of AL-BBRB specimens. According to test results of all specimens, stable hysteretic curves were obtained without any local and overall buckling. Consequently, the hysteretic behavior of AL-BBRB specimens is highly concerned with the design variables. Besides, failure positions of AL-BBRB specimens often concentrates on the end of the segment, which can be exactly predicted. Based on test results of all specimens, AL-BBRB specimens show a promising future for wide application in new or retrofitted buildings/bridges where lack the excellent seismic behavior and durability.

An Investigation of Size Effect on Fatigue Property of 3000 MPa-Class Mould Steel Under Ultrasonic Fatigue Testing

2012 ◽  
Vol 239-240 ◽  
pp. 88-91
Author(s):  
Wen Jie Peng ◽  
Hui Cai Long ◽  
Li Yu ◽  
Huan Xue ◽  
Bao Wen Qiu ◽  
...  
Keyword(s):  
Size Effect ◽  
Fatigue Testing ◽  
Fatigue Behavior ◽  
Fatigue Property ◽  
High Strength ◽  
Fatigue Tests ◽  
Test Results ◽  
Fatigue Specimen ◽  
Ultrasonic Fatigue

Ultrasonic fatigue testing was conducted for 3000 MPa-class mould steel to investigate the fatigue behavior. The fatigue specimen is designed particularly due to the ultra-high strength. Ultrasonic fatigue tests are conduced using two types of specimen sizes and the test results are compared to investigate the size effect on the fatigue property.

Evaluation and Validation of Fatigue Testing Methods for Rubberized Bituminous Specimens

2019 ◽  
Vol 2673 (8) ◽  
pp. 603-610 ◽  
Author(s):  
Huayang Yu ◽  
Zihan Zhu ◽  
Duanyi Wang
Keyword(s):  
Fatigue Test ◽  
Fatigue Testing ◽  
Fatigue Behavior ◽  
Crumb Rubber ◽  
Fatigue Performance ◽  
Organic Chemical ◽  
Poor Correlation ◽  
Test Results ◽  
Asphalt Rubber ◽  
Shear Fatigue

Several fatigue evaluation methods are available to evaluate the durability of bituminous materials. In some cases, the test results may provide poor correlation with the true fatigue performance, especially when additives with complicated components are incorporated. This study aims to characterize the fatigue behavior of different warm asphalt rubber (WAR) specimens modified by both crumb rubber and warm mix asphalt (WMA) additives, and to validate the feasibility of binder and mortar fatigue tests on WAR. Three WARs with organic, chemical, and foaming additives were prepared. G*sin δ and liner amplitude sweep (LAS) tests (on both binders and liquid phases), and the shear fatigue test (on mortars) were performed. The four-point bending beam (4PB) test was used as reference to validate results of binder, liquid phase, and mortar tests. Test results indicated that the fatigue performance of virgin bitumen is obviously improved by crumb rubber. The selected organic additive contributes to superior fatigue resistance, whereas WARs with foaming and chemical WMA modifiers performed more poorly than asphalt rubber in relation to fatigue, but still much better that the non-rubberized samples. Finally, it is noted that for the rubberized bituminous specimens, LAS evaluation for asphalt binder and the shear fatigue test for asphalt mortar provide same prediction as the 4PB test, whereas other tests give inconsistent results. Therefore, it is suggested to use the 4PB test on mixture, the LAS test on binder, and the shear fatigue test on mortar for fatigue performance characterization of bituminous specimens containing crumb rubber particles. Further validation of the above findings on field specimens is suggested.

Fatigue of Unidirectional Cord-Rubber Composites

1999 ◽  
Vol 27 (1) ◽  
pp. 48-57 ◽  
Author(s):  
Y. Liu ◽  
Z. Wan ◽  
Z. Tian ◽  
X. Du ◽  
J. Jiang ◽  
...  
Keyword(s):  
Damage Accumulation ◽  
Fatigue Testing ◽  
Fatigue Behavior ◽  
Constant Load ◽  
Testing System ◽  
Rubber Composites ◽  
Cycle Frequency ◽  
Periodic Loading ◽  
Fatigue Damage Accumulation ◽  
Rubber Composite

Abstract A fatigue testing system is established with which the real-time recording of stress, strain, temperature, and hysteresis loss of rubbers or cord-rubber composite specimens subjected to periodic loading or extension can be successfully carried out. Several problems are connected with the experimental study of the fatigue of rubber composites. In constant extension cycling, the specimen becomes relaxed because of the viscoelasticity of rubber composites, and the imposed tension-tension deformation becomes complex. In this method, the specimen is unlikely to fail unless the imposed extensions are very large. Constant load cycling can avoid the shortcomings of constant extension cycling. The specially designed clamps ensure that the specimen does not slip when the load retains a constant value. The Deformation and fatigue damage accumulation processes of rubber composites under periodic loading are also examined. Obviously, the effect of cycle frequency on the fatigue life of rubber composites can not be ignored because of the viscoelasticity of constituent materials. The increase of specimen surface temperature is relatively small in the case of 1 Hz, but the temperature can easily reach 100°C at the 8 Hz frequency. A method for evaluating the fatigue behavior of tires is proposed.

scholarly journals Assessment of Lacrimal Duct Patency in Patients Undergoing Endoscopic Medial Maxillectomy

2021 ◽  
Vol 10 (2) ◽  
pp. 245
Author(s):  
Andrzej Sieśkiewicz ◽  
Tomasz Łysoń ◽  
Marek Rogowski ◽  
Marek Bielecki ◽  
Ewa Gindzienska-Sieskiewicz ◽  
...  
Keyword(s):  
Assessment Method ◽  
Test Results ◽  
Functional Disorders ◽  
Lacrimal Duct ◽  
Assessment Tests ◽  
Number Of Patients ◽  
Study Results ◽  
Assessment Techniques ◽  
Medial Maxillectomy ◽  
Comparison Of The Results

Purpose: The risk of epiphora after medial maxillectomy with lacrimal duct transection is difficult to assess. The data available in the literature are inconclusive due to various operating techniques used by the authors of medical publications, different additional procedures aimed at improving tear drainage after maxillectomy, and a variety of lacrimal duct patency assessment techniques. The aim of our work was to assess the anatomical and functional patency of lacrimal ducts after medial maxillectomy without performing additional procedures to improve tear drainage as well as comparison of the results obtained with different assessment tests. Materials and methods: 21 patients who underwent medial maxillectomy in the years 2016–2019 were assessed for discomfort and epiphora based on patients’ own reports and basic clinical examination, lacrimal duct rinse test, the Munk score, and a modified endoscopic Jones I test. Results: Gradually increasing the sensitivity of the assessment method resulted in an increase in the number of patients with potential tear drainage disorders, starting from 0% in the rinsing test, 4.8% self-reported tearing complaints, 14.3% Munk score, and 19% modified endoscopic Jones I test. Conclusions: The study results revealed that a small fraction of patients tend to report epiphora as a consequence of medial maxillectomy themselves. Subtle functional disorders, which are not particularly bothersome to patients, are more common. More sensitive lacrimal duct patency tests reveal more cases of tear drainage disorders. The results of studies assessing the incidence of epiphora after medial maxillectomy appear to depend on the type of test used.

Partial Devitrification of Sintered Silicon Nitride During Static Fatigue Testing

1992 ◽  
Vol 287 ◽  
Author(s):  
W. Braue ◽  
G. D. Quinn
Keyword(s):  
Fatigue Testing ◽  
Fatigue Behavior ◽  
Slow Crack Growth ◽  
Stress Rupture ◽  
Secondary Phase ◽  
Boundary Phase ◽  
Static Fatigue ◽  
Phase Assemblage ◽  
Transmission Electron ◽  
Stress States

ABSTRACTThe static fatigue behavior of sintered Y2O3/A12O3-fluxed Si3N4 in air is controlled by slow crack growth or creep fracture. Partial devitrification of the amorphous grain boundary phase at 1000°C and 1100°C improves the static fatigue resistance with specimens surviving up to 1500 hrs. during stress rupture experiments. In this study the early stages of partial devitrification during static fatigue testing at 1000°C are investigated by conventional and analytical transmission electron microscopy with emphasis on nucleation and growth of δ-Y2Si2O7 and X1-Y2SiO5 and possible constraints from different stress states. The results show that the stress state does not affect the nature of the secondary phase assemblage. However, the amount of crystallization is higher within the tensile region of the flexural specimens than in areas which experienced compressive stresses.

Effects of Surface Finish and Loading Conditions on the Low Cycle Fatigue Behavior of Austenitic Stainless Steel in PWR Environment for Various Strain Amplitude Levels

2009 ◽  
Author(s):  
Jean Alain Le Duff ◽  
Andre´ Lefranc¸ois ◽  
Jean Philippe Vernot
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Strain Amplitude ◽  
Surface Finish ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Complex Loading ◽  
Loading Conditions ◽  
Test Results ◽  
Cycle Fatigue

In February/March 2007, The NRC issued Regulatory Guide “RG1.207” and Argonne National Laboratory issued NUREG/CR-6909 that is now applicable in the US for evaluations of PWR environmental effects in fatigue analyses of new reactor components. In order to assess the conservativeness of the application of this NUREG report, Low Cycle Fatigue (LCF) tests were performed by AREVA NP on austenitic stainless steel specimens in a PWR environment. The selected material exhibits in air environment a fatigue behavior consistent with the ANL reference “air” mean curve, as published in NUREG/CR-6909. LCF tests in a PWR environment were performed at various strain amplitude levels (± 0.6% or ± 0.3%) for two loading conditions corresponding to a simple or to a complex strain rate history. The simple loading condition is a fully reverse triangle signal (for comparison purposes with tests performed by other laboratories with the same loading conditions) and the complex signal simulates the strain variation for an actual typical PWR thermal transient. In addition, two various surface finish conditions were tested: polished and ground. This paper presents the comparisons of penalty factors, as observed experimentally, with penalty factors evaluated using ANL formulations (considering the strain integral method for complex loading), and on the other, the comparison of the actual fatigue life of the specimen with the fatigue life predicted through the NUREG report application. For the two strain amplitudes of ± 0.6% and ± 0.3%, LCF tests results obtained on austenitic stainless steel specimens in PWR environment with triangle waveforms at constant low strain rates give “Fen” penalty factors close to those estimated using the ANL formulation (NUREG/6909). However, for the lower strain amplitude level and a triangle loading signal, the ANL formulation is pessimistic compared to the AREVA NP test results obtained for polished specimens. Finally, it was observed that constant amplitude LCF test results obtained on ground specimens under complex loading simulating an actual sequence of a cold and hot thermal shock exhibits lower combined environmental and surface finish effects when compared to the penalty factors estimated on the basis of the ANL formulations. It appears that the application of the NUREG/CR-6909 in conjunction with the Fen model proposed by ANL for austenitic stainless steel provides excessive margins, whereas the current ASME approach seems sufficient to cover significant environmental effects for representative loadings and surface finish conditions of reactor components.

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