Modeling of Internal Damage Evolution of Piezoelectric Ceramics Under Compression-Compression Fatigue Tests

2015 ◽  
pp. 231-240
Author(s):  
Mamoru Mizuno ◽  
Ken-ichi Wakui
Keyword(s):  
Damage Evolution ◽  
Piezoelectric Ceramics ◽  
Fatigue Tests ◽  
Internal Damage

Modeling of Internal Damage Evolution During Actuation Fatigue in Shape Memory Alloys

2018 ◽  
Author(s):  
Francis R. Phillips ◽  
Daniel Martin ◽  
Dimitris C. Lagoudas ◽  
Robert W. Wheeler
Keyword(s):  
Phase Transformation ◽  
Constitutive Model ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Damage Evolution ◽  
Low Cycle Fatigue ◽  
Cycle Fatigue ◽  
Internal Damage ◽  
Functional Fatigue ◽  
Non Linear

Shape memory alloys (SMAs) are unique materials capable of undergoing a thermo-mechanically induced, reversible, crystallographic phase transformation. As SMAs are utilized across a variety of applications, it is necessary to understand the internal changes that occur throughout the lifetime of SMA components. One of the key limitations to the lifetime of a SMA component is the response of SMAs to fatigue. SMAs are subject to two kinds of fatigue, namely structural fatigue due to cyclic mechanical loading which is similar to high cycle fatigue, and functional fatigue due to cyclic phase transformation which typical is limited to the low cycle fatigue regime. In cases where functional fatigue is due to thermally induced phase transformation in contrast to being mechanically induced, this form of fatigue can be further defined as actuation fatigue. Utilizing X-ray computed microtomography, it is shown that during actuation fatigue, internal damage such as cracks or voids, evolves in a non-linear manner. A function is generated to capture this non-linear internal damage evolution and introduced into a SMA constitutive model. Finally, it is shown how the modified SMA constitutive model responds and the ability of the model to predict actuation fatigue lifetime is demonstrated.

Fatigue Analysis of the Asphalt Mixture Beam Using Damage Evolution Equations

2010 ◽  
Vol 163-167 ◽  
pp. 3332-3335 ◽  
Author(s):  
Ding Han ◽  
Bing Gen Zhan ◽  
Xiao Ming Huang
Keyword(s):  
Fracture Toughness ◽  
Damage Evolution ◽  
Life Prediction ◽  
Evolution Equations ◽  
Asphalt Mixture ◽  
Fatigue Tests ◽  
Toughness Index ◽  
Residual Fatigue ◽  
Stress Damage ◽  
Fully Coupled

Damage evolution equations of asphalt mixture specimen beams were analyzed using the fracture toughness index and the ultimate tension strain index, respectively. The fracture toughness of the asphalt mixture was calculated by FEM. Damage evolution equations controlled apart by the stress and the strain were given. Their coefficients were back-calculated using partial fatigue tests data. The fully coupled stress-damage method and the fully coupled strain-damage method were used. The life prediction precision of each equation was verified by residual fatigue tests data. The results show that FEM is effective to calculate the fracture toughness of the asphalt mixture. Two damage evolution equations have better life prediction abilities comparing with the S-N equation used usually.

Experimental Study on the Flexural Fatigue Damage Evolution of Layered Fiber Reinforced Concrete

2008 ◽  
Vol 385-387 ◽  
pp. 673-676
Author(s):  
Ji Wang ◽  
Ming Zhong Zhang ◽  
Xiao Chun Fan
Keyword(s):  
Reinforced Concrete ◽  
Fatigue Life ◽  
Damage Evolution ◽  
Steel Fiber ◽  
Fatigue Tests ◽  
Fiber Reinforced Concrete ◽  
Fiber Reinforced ◽  
Steel Fiber Reinforced Concrete ◽  
Flexural Fatigue ◽  
Order Of Magnitude

In order to study the damage evolution law for layered fiber reinforced concrete subjected to flexural fatigue, the flexural fatigue tests were carried out on both layered steel fiber reinforced concrete(LSFRC) and layered hybrid fiber reinforced concrete(LHFRC) beams of which the type of steel fiber was uniform on the same concrete mix. At the same time the flexural fatigue tests with original concrete(OC) were carried out. Based on the experiments, both flexural fatigue life and damage characteristic of LSFRC LHFRC and OC were compared and analyzed. The results indicated that the fatigue life of LHFRC was a little larger than that of LSFRC under the stress level, which was more than an order of magnitude of OC. And the fatigue distortion of LSFRC, LHFRC and OC were similar. They all followed three-phase law. However, the proportion of every phase was different, which proved that layered steel fibers and polypropylene fibers could effectively restrain the degradation of concrete.

Study Asphalt Mixture Damage Characteristics Based on X-CT Technology

2013 ◽  
Vol 831 ◽  
pp. 401-406
Author(s):  
Zhi Yong Wu ◽  
Xiao Ning Zhang ◽  
Hong You ◽  
Cheng Wan
Keyword(s):  
Computerized Tomography ◽  
Damage Evolution ◽  
Asphalt Mixture ◽  
Curvilinear Relationship ◽  
Internal Damage ◽  
X Ray ◽  
Damage Process ◽  
Ct Technology ◽  
Strain Stress ◽  
Important Basis

In order to research the development of the internal cracks and the evolution of damage in asphalt mixture under loads, German Compact-225 type industrial X-ray computerized tomography (X-CT) was used to scan the specimen of asphalt mixture and the visualization of the internal damage process could be achieved, the damage under loads in various stages could be described accurately. Then, the damage evolution process was analyzed by calculating CT numbers, and a curvilinear relationship between the damage variable and the strain-stress was established. The results indicate that X-CT technology can be used as an effective way to detect and analyze the meso-damage of the asphalt mixture and that it further provides an important basis for quantitatively describing the evolution rule of the meso-damage.

The Influence of HAZ on Fatigue Life of 16Mn Steel

2008 ◽  
Vol 44-46 ◽  
pp. 323-328
Author(s):  
Gang Chen ◽  
Xue Mei Luo ◽  
Xu Chen ◽  
Wei Hua Zhang
Keyword(s):  
Fatigue Life ◽  
Base Metal ◽  
Damage Evolution ◽  
Welded Joint ◽  
Peak Stress ◽  
Cyclic Fatigue ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Decline Curves ◽  
16Mn Steel

In order to understand the influence of Heat-Affected Zone (HAZ) on fatigue properties of 16Mn steel, a series of cyclic torsional tests were conducted on 16Mn weld metal, the base metal, and the HAZ metal. The specimens of 2mm diameter were uniformly-spaced taken from a bulk 16Mn plate, which included a V-style welded joint in the center, and the space for each specimen was 4mm. From cyclic fatigue tests performed on specimens at different positions, one can observe that the fatigue damage evolution in the HAZ is faster than those in the weld and the base metal, i.e., HAZ has a significant effect on fatigue life of 16Mn. In addition, the peak stress decline curves of HAZ specimens in different rows are considerably diversified, but the damage evolution and fatigue properties of HAZ metal are similar in spite of their locations.

Research on Landscape Limestone Damage and Deformation under Uniaxial Compression Based on Acoustic Emission

2013 ◽  
Vol 423-426 ◽  
pp. 914-919 ◽  
Author(s):  
Yong Qin Xiao ◽  
Yi Ping Wan ◽  
Bao Xian Liu
Keyword(s):  
Acoustic Emission ◽  
Uniaxial Compression ◽  
Damage Evolution ◽  
Detection System ◽  
Damage Model ◽  
Mechanical Damage ◽  
Test System ◽  
Emission Feature ◽  
Internal Damage ◽  
Emission Parameter

In order to establish the relation between acoustic emission parameter and rock mechanical damage mechanism, as well as to better figure out landscape limestone damage and deformation influenced by uniaxial compression, MTS815 rock mechanical electro-hydraulic servo test system and 8CHSPCI-2 acoustic emission and detection system are applied to implement a test and research on damage evolution of limestone under uniaxial compression and the corresponding acoustic emission feature. On this basis, the acoustic emission feature of limestone under uniaxial compression is analyzed. Moreover, based on the damage variable of normalized accumulated emission ringing count, the uniaxial compression limestone damage model based on acoustic emission feature is established, and the damage evolution curve and equation of limestone is figured out as well. Shown by the research, acoustic emission information reflects the internal damage of limestone, and is closely related with densification of inner original fracture, as well as emerging, developing, and merging of new fractures. The acoustic emission feature of limestone perfectly describes its deformation and damage evolution.

Sign in / Sign up

Export Citation Format

Share Document