Experimental Study of Full-Scale Buckling Restrained Brace With Inspection Windows

2017 ◽  
Author(s):  
C. S. Tsai ◽  
Hui-Chen Su ◽  
T. C. Chiang
Keyword(s):  
Experimental Study ◽  
Energy Dissipation ◽  
Low Cycle Fatigue ◽  
Fatigue Tests ◽  
Full Scale ◽  
Test Results ◽  
Cycle Fatigue ◽  
Buckling Restrained Brace ◽  
Steel Core ◽  
Testing Protocols

The buckling restrained brace (BRB) has been worldwide accepted as a powerful tool to protect structures from earthquake damage. However, the steel core of the traditional BRB is enclosed by the buckling-restraining unit, it is therefore impossible to observe the condition of the steel core during manufacturing and after earthquakes. Presented in this paper is experimental study on a full-scale buckling restrained brace with inspection windows that allow directly observing the condition of the internal components of the BRB, especially for the steel core. Experimental study in deciding the sizes and locations of the inspection windows to inspect the condition of the steel core during testing without influencing the functionality of the full-scale BRB has been conducted to search for a feasible BRB that is economical and convenient for manufacturing and installation as well as meets testing protocols. Test results of the full-scale BRBs under cyclic loadings showed that the mechanical behavior of the full-scale BRB with inspection windows opened on the buckling-restraining unit was stable and that fracture always occurred at the energy dissipation segments after low cycle fatigue tests. The condition of the steel core can be clearly observed through the inspection windows without dismantling the device during the tests. The test results also indicate that the selected inspection windows on the full-scale BRB have little influence on the strength of the device and that an appropriately designed BRB device with inspection windows can be considered as a stable energy dissipation device. A good indicator to decide the necessity of replacement of the BRB device to prepare for next earthquakes has also been proposed in this study.

Buckling Restrained Brace With Inspection Windows

2015 ◽  
Author(s):  
C. S. Tsai ◽  
Yi Liu ◽  
B. Q. Liu
Keyword(s):  
Experimental Study ◽  
Energy Dissipation ◽  
Mechanical Behavior ◽  
Low Cycle Fatigue ◽  
Fatigue Tests ◽  
Test Results ◽  
Cycle Fatigue ◽  
Buckling Restrained Brace ◽  
Steel Core ◽  
Testing Protocols

The buckling restrained brace (BRB) has been worldwide recognized as an energy absorber to protect structures from earthquake damage. However, the traditional BRB is a fully close design, it is therefore impossible to detect the condition of the steel core during manufacturing and after earthquakes. This paper proposed a buckling restrained brace with inspection windows that allow inspecting the condition of the internal components of the BRB. Experimental study in selecting the sizes and locations of the inspection windows without affecting the functionality of the BRB has been carried out to search for an economically feasible BRB that is convenient for manufacturing and installation and meets testing protocols. Test results of the proposed BRBs under cyclic loadings showed that the mechanical behavior of the BRB with inspection windows on the buckling-restraining unit consisting of the constraining and lateral support elements was stable and that damage always occurred at the energy dissipation segments after low cycle fatigue tests. These test results indicate that the inspection windows opened on the proposed BRB have little influence on the strength of the device and that the proposed device can be considered as a stable energy dissipation device.

Experimental Study of All-Steel Buckling Restrained Brace With Windowed Lateral Support Elements

2014 ◽  
Author(s):  
Chong-Shien Tsai ◽  
Yan-Ming Wang
Keyword(s):  
Energy Dissipation ◽  
Structural Control ◽  
Low Cycle Fatigue ◽  
Control Device ◽  
Fatigue Tests ◽  
Test Machine ◽  
Test Results ◽  
Buckling Restrained Brace ◽  
Steel Core ◽  
The Difference

The buckling restrained brace (BRB) that has been worldwide adopted as a structural control device possesses excellent energy dissipation mechanism and can overcome the disadvantages of the traditional brace. However, the traditional BRB is a fully close design, it is therefore impossible to inspect the condition of the internal components during manufacturing and after earthquakes. This study proposed an all-steel buckling restrained brace with windowed lateral support elements that allow inspecting the internal condition of the BRB. We also studied the optimization in selecting the sizes and positions of the windows in the internal components without affecting its strength to provide an economically feasible all-steel BRB that is convenient for manufacturing and installation and meets the rigorous testing protocols. The all-steel BRB consists of the steel core, lateral support and constraining elements. In this study, scaled all-steel BRBs were tested under cyclic loadings by using an MTS 250 kN test machine. Test results showed that the mechanical behavior of the BRB with windows on the sides of lateral support elements is stable and that damage always occurred at the energy dissipation sections after low cycle fatigue tests. The difference between tensile and compressive forces was small under identical strain, and the accumulated inelastic deformation exceeded the requirement of test protocols. These test results confirm that the windows opened on the proposed BRB have insignificant effects on the strength of the device and that the proposed device meets the design requirement and is thus considered as a stable energy dissipative apparatus.

Experimental Study of Viscoelastic Dampers under Large Deformation

2012 ◽  
Vol 166-169 ◽  
pp. 2226-2233 ◽  
Author(s):  
Gang Zhao ◽  
Peng Pan ◽  
Jia Ru Qian ◽  
Jin Song Lin
Keyword(s):  
Mechanical Properties ◽  
Experimental Study ◽  
Energy Dissipation ◽  
Low Cycle Fatigue ◽  
Loss Modulus ◽  
Fatigue Behavior ◽  
Fatigue Tests ◽  
Small Displacement ◽  
Loading Frequency ◽  
Cycle Fatigue

The paper presents an experimental study on a new type viscoelastic damper, which is expected to have better energy dissipation capability. Tests on the dampers’ mechanical properties, including shear storage modulus, shear loss modulus, and loss factor, were conducted using reduced scale specimens, and took strain amplitude, loading frequency and ambient temperature as test parameters. Aging tests, low cycle and high cycle fatigue tests were also conducted. Particularly, the low cycle fatigue behavior under a strain of 300% and the basic mechanical behavior under strains of 300%-420% were investigated. Test results suggest that the dependency of the mechanical properties on frequency and temperature is small, the energy dissipation capacity is stable for both large and small displacement, and the damper reaches a strain of 420% without failure.

Experimental Investigation on the Creep and Low Cycle Fatigue Behaviors of a Serviced Turbine Blade

2019 ◽  
Author(s):  
Zhenlei Li ◽  
Duoqi Shi ◽  
Xiaoguang Yang ◽  
Nina Li
Keyword(s):  
Turbine Blade ◽  
Low Cycle Fatigue ◽  
Test System ◽  
Fatigue Tests ◽  
Test Results ◽  
Cycle Fatigue ◽  
Hold Period ◽  
Low Pressure Turbine ◽  
Creep Fatigue ◽  
Crack Initiation Life

Abstract This paper experimentally investigated the creep and fatigue behaviors of a low-pressure turbine (LPT) blade with 600 hours of service using a novel test system. Pure low cycle fatigue (LCF), pure creep and creep-fatigue interaction (CFI) experiments on the full-scale serviced blades were conducted respectively. Test results showed that the increasing of deformation amplitude was divided into three stages under both pure LCF and creep-fatigue loadings. The deformation of each blade increased rapidly until failure when the test cycle exceeded the 80% of their overall life under the pure LCF and CFI condition. The hold period in creep-fatigue tests shortens the first stage of whole life and has no influence on the proportion of crack initiation life to overall life. The fractures in pure LCF, pure creep and creep-fatigue tests emerged transgranular, intergranular and both transgranular and intergranular behaviors respectively. The crack initiated and propagated in a specific zone of the blade under all the experimental loadings, which limited its creep-fatigue resistance. At last, the remaining life of turbine blade was estimated conservatively by introducing the safety limit into a statistical method.

Influences of Cyclic Pre-Overload on Low Cycle Fatigue Behaviours of Elbow Pipe

2011 ◽  
Author(s):  
Kazuya Matsuo ◽  
Koji Takahashi ◽  
Kyohei Sato
Keyword(s):  
Low Cycle Fatigue ◽  
Three Dimensional ◽  
Preliminary Test ◽  
Growth Direction ◽  
Fatigue Tests ◽  
Test Results ◽  
Cycle Fatigue ◽  
Crack Penetration ◽  
Crack Growth Direction ◽  
Cumulative Fatigue Damage

Low cycle fatigue tests were conducted using sound elbows made of carbon steel (STPT410). The elbows were subjected to cyclic in-plane bending under displacement control with internal pressure of 9 MPa. The preliminary fatigue tests were conducted under constant cyclic displacements. Then, two test conditions were adopted to investigate the influence of cyclic pre-overload on low cycle behavior of elbow on the basis of the preliminary test results. The fatigue test results were evaluated by using the total usage factor UFTotal (= UFpre+UFpost), where the UFpre and UFpost correspond to usage factor for δpre and δpost, respectively. The fatigue lives of overloaded elbow pipes were estimated based on the cumulative fatigue damage rule basically from UFpre = 0.2 to UFpre = 0.6. In addition, three-dimensional elastic-plastic analyses were carried out using the finite element method. The crack penetration area and the crack growth direction were successfully predicted by the analyses.

Cyclic Behavior of Class U Wheel Steel

1981 ◽  
Vol 103 (1) ◽  
pp. 113-118 ◽  
Author(s):  
Y. J. Park ◽  
D. H. Stone
Keyword(s):  
Low Cycle Fatigue ◽  
Cyclic Softening ◽  
Fatigue Tests ◽  
Wheel Steel ◽  
Cyclic Behavior ◽  
Fatigue Properties ◽  
Test Results ◽  
Cycle Fatigue ◽  
Lower Strain ◽  
Service Environments

In order to evaluate the material properties of Class U wheel steel under cyclic loading, low-cycle fatigue tests were conducted at room temperature on specimens taken from the rim of the wheel. The test results show that Class U wheel steel experiences significant cyclic softening at lower strains, but cyclically hardens at larger strain levels. Due to the cyclic softening at lower strain levels, the steel will plastically deform, even at stresses of about one-half of the monotonic yield strength. Quantitative fatigue properties, which can then be used to predict accurate fatigue lives of various components of wheels under complex service environments, are also obtained from the low-cycle fatigue tests.

scholarly journals Comments on Linear Summation Hypothesis of Fatigue Failures

2014 ◽  
Vol 21 (3) ◽  
pp. 77-85 ◽  
Author(s):  
Grzegorz Szala
Keyword(s):  
High Cycle Fatigue ◽  
Low Cycle Fatigue ◽  
Fatigue Tests ◽  
Load Level ◽  
Test Results ◽  
Cycle Fatigue ◽  
Load Spectrum ◽  
Linear Summation ◽  
Analysis Of Results ◽  
Fatigue Failures

Abstract This paper presents a comparative analysis of results of fatigue life calculations with the u se of the linear summation hypothesis of fatigue failures (LHSUZ), confronted with experimental test results. Te calculations and fatigue tests were performed for variable amplitude(VA), two-step and ten-step loading conditions, both in the low-cycle fatigue (LCF) and high-cycle fatigue (HCF) range, for the case of C45 steel as an example. Experimental verification of the hypothesis LHSUZ did not revealed any significant influence of load level and form of load spectrum on conformity of results of the calculation by using the LHSUZ, to results of fatigue tests on C45 steel. However, it enabled to assess magnitude of a correction factor which appears in the considered linear hypothesis.

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.

Investigation on Material's Fatigue Property Variation Among Different Regions of Directional Solidification Turbine Blades—Part II: Fatigue Tests on Bladelike Specimens

2014 ◽  
Vol 136 (10) ◽  
Author(s):  
Xiaojun Yan ◽  
Mingjing Qi ◽  
Ying Deng ◽  
Xia Chen ◽  
Ruijie Sun ◽  
...  
Keyword(s):  
Directional Solidification ◽  
Maximum Stress ◽  
Low Cycle Fatigue ◽  
Turbine Blades ◽  
Fatigue Property ◽  
Fatigue Tests ◽  
Full Scale ◽  
Test Results ◽  
Property Variation ◽  
Stress Region

Part I of this investigation is mainly focused on fatigue tests of full scale turbine blades, based on the observation of the phenomena that some directional solidification (DS) blades do not fracture at their maximum stress region, and it has been revealed that there exists material's fatigue property variation among different regions of DS blades. For more in-depth and quantitative study on the fatigue property variation, Part II of this investigation designs and fabricates four types of DS bladelike specimens (including platform-, shroud-, body-, and rootlike specimens), which imitate the geometry, microstructure, and stress features of a full scale turbine blade on its four typical regions, to conduct the low cycle fatigue (LCF) tests. Test results show that the bodylike specimen has the best fatigue performance, and under the same stress state, the fatigue life of root-, shroud-, and platformlike specimens are 29.1%, 28.5%, and 13.7% of the bodylike specimen, respectively. The large material's fatigue property variation among different regions of DS blades should be considered in future blade life design.

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