Journal articles on the topic 'Dynamic damage'
To see the other types of publications on this topic, follow the link: Dynamic damage.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 journal articles for your research on the topic 'Dynamic damage.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.
1
Bhargav Sai, Cherukuri, and D. Mallikarjuna Reddy. "Dynamic Analysis of Faulty Rotors through Signal Processing." Applied Mechanics and Materials 852 (September 2016): 602–6. http://dx.doi.org/10.4028/www.scientific.net/amm.852.602.
Abstract:
In this study, an effective method based on wavelet transform, for identification of damage on rotating shafts is proposed. The nodal displacement data of damaged rotor is processed to obtain wavelet coefficients to detect, localise and quantify damage severity. Because the wavelet coefficients are calculated with various scaled indices, local disturbances in the mode shape data can be found out in the finer scales that are positioned at local disturbances. In the present work the displacement data are extracted from the MATLAB model at a particular speed. Damage is represented as reduction in diameter of the shaft. The difference vectors between damaged and undamaged shafts are used as input vectors for wavelet analysis. The measure of damage severity is estimated using a parameter formulated from the distribution of wavelet coefficients with respect to the scales. Diagnosis results for different damage cases such as single and multiple damages are presented.
2
Sun , Yun, Qiuwei Yang, and Xi Peng. "Structural Damage Assessment Using Multiple-Stage Dynamic Flexibility Analysis." Aerospace 9, no. 6 (May 29, 2022): 295. http://dx.doi.org/10.3390/aerospace9060295.
Abstract:
Vibration-based damage assessment technology is a hot topic in aerospace engineering, civil engineering, and mechanical engineering. In this paper, a damage assessment approach using multiple-stage dynamic flexibility analysis is proposed for structural safety monitoring. The proposed method consists of three stages. The content of Stage I is to determine the number of damaged elements in the structure by the rank of dynamic flexibility change. The content of Stage II is to determine damage locations by the minimum rank of flexibility correlation matrices. Finally, the damage extents of those damaged elements are calculated in Stage III. The proposed approach fully uses the filtering ability of matrix rank analysis for data noise. A 27-bar truss structure and a steel frame structure are used as the numerical and experimental examples to demonstrate the proposed method, respectively. From the numerical and experimental results, it is found that structure damages can be successfully identified through the multiple-stage dynamic flexibility analysis. By comparative study, the proposed method has more powerful antinoise ability and higher calculation accuracy than the generalized flexibility method. The proposed method may be a promising tool for structural damage assessment.
3
Mahendran, G., Chandrasekaran Kesavan, and S. K. Malhotra. "Damage Detection in Laminated Composite Beams, Plates and Shells Using Dynamic Analysis." Applied Mechanics and Materials 787 (August 2015): 901–6. http://dx.doi.org/10.4028/www.scientific.net/amm.787.901.
Abstract:
Vibration-based technique to detect damage in laminated composite beams, rectangular plates and cylindrical shells is presented in this paper.A parameter called damage indicator calculated based on mode shape curvature isused in this studyto detect the location and size of small damages accurately in laminated composite structures. Through numerical analysis of laminated compositecantilevered beam, plate and cylindrical shell models with edge crack as damage, the absolute change inthe damage indicator is localized in the region of damage. Thechange in damage indicatorincreases withincreasing size of damage. Thisinformationis obtained by considering two cases of damage sizes (case-1 and case-2)in the structures. Finite element methodbased commercial analysis package ANSYSis used to obtain thenormalized displacement mode shapesof the three models both for intact and damaged states and then the damage indicator is calculated from the mode shapes data.The numerical analysis to detect damage is followed by validation by experimental modal testing.
4
LI, S. C., S. H. LIU, and Y. L. WU. "A NEW TYPE OF CAVITATION DAMAGE TRIGGERED BY BOUNDARY-LAYER TURBULENT PRODUCTION." Modern Physics Letters B 21, no. 20 (August 30, 2007): 1285–96. http://dx.doi.org/10.1142/s0217984907013456.
Abstract:
A new type of cavitation damage has been observed on the turbines installed at the Three Gorges Power Station despite no cavitation detected during model tests. Metallurgical and fluid dynamic analysis suggests that this cavitation is triggered by boundary-layer turbulent production; the damaged (roughened) spot in turn triggers subsequent cavitation (damage) immediately down stream. This forms a sustainable dynamic process, resulting in long and equal-width streamwise damage-strips with spanwise regularity reflecting the spanwise stochastic characteristics of turbulent production. Owing to the heat effect of cavitation, intergranular corrosion takes place through sensitization process, leaving the damaged surface with a corrosion appearance. Also, bluing presents at the damaged tails, owing to the nature of low-intensity damage. Extremely large turbines are much more susceptible to this type of cavitation (damage) owing to the similarity laws currently employed for turbine development not concerning the freestream turbulence and the boundary-layer dynamics.
5
SILVA, R. L., L. M. TRAUTWEIN, C. S. BARBOSA, L. C. ALMEIDA, and G. H. SIQUEIRA. "Empirical method for structural damage location using dynamic analysis." Revista IBRACON de Estruturas e Materiais 13, no. 1 (February 2020): 19–31. http://dx.doi.org/10.1590/s1983-41952020000100003.
Abstract:
Abstract This paper presents the use of numerical model techniques for identification and damage location adopting the Modal Curvature Difference (MCD) method as reference for the analysis of a simply supported concrete structure. Then, an empirical formulation to detect damages in this structure is proposed. In this method, called Acceleration Summation Difference (ASD), the difference of acceleration amplitude between intact and damaged structures are calculated for concrete plates simply supported on rubber bearings. During the analyses, the finite element models were developed using SAP2000® software. The results obtained depicted that it is possible to determine the approximate position of one or more damages in the structure, with some restrictions, and the proposed ASD method presented good correlation to localize the position of single or multiple damages.
6
Zhao, Mingjie, Guoyin Wu, and Kui Wang. "Comparative Analysis of Dynamic Response of Damaged Wharf Frame Structure under the Combined Action of Ship Collision Load and Other Static Loads." Buildings 12, no. 8 (July 30, 2022): 1131. http://dx.doi.org/10.3390/buildings12081131.
Abstract:
In the long-term service, the wharf structure can be damaged by ship impact, wave load, and even earthquake, which will affect the safe production and smooth operation of the port. Based on the theory of structural dynamic response analysis and wavelet packet analysis principle, this paper established the damage identification index of the wharf frame structure. Combining with the finite element method and the dynamic response theory of the wharf frame structure, it set up a finite element analysis model of the dynamic response of the wharf frame structure under the action of multiple loads, with the impact load of the ship as the dynamic load under the non-damaged state and the different damaged states. In addition, the characteristic response point location was drawn up. Furthermore, the transient dynamic analysis and damage index analysis of the frame structure in the non-damaged and damaged state were conducted respectively. In addition, the model test and numerical simulation results were combined to compare and analyze the identification of damage indicators, so as to verify the identification effect of the established damage identification indicators on the structural damage, which lays a foundation for the next step of structural damage identification.
7
ZHANG, Hougui, Ruixiang SONG, Jie YANG, Dan WU, and Yingjie WANG. "Connection Damage Detection of Double Beam System under Moving Load with Genetic Algorithm." Mechanics 27, no. 1 (February 24, 2021): 80–87. http://dx.doi.org/10.5755/j02.mech.25500.
Abstract:
In this paper, a novel damage detection approach for the spring connection of the double beam system using the dynamic response of the beam and genetic algorithm is presented. The double beam system is regarded as both Bernoulli-Euler beams with simply supported ends, the upper and lower beams are connected by a series of linear springs with certain intervals. With the genetic algorithm, the dynamic acceleration response of double beam system under moving load, which can be solved by the Newmark-β integration procedure, is used as the input data to detect the connection damage. Thus the dynamic response of the double beam system with a certain damage pattern can be calculated employing the moving load model. If the calculated result is quite close to the recorded response of the damaged bridge, this damage pattern will be the solution. The connection damage detection process of the proposed approach is presented herein, and its feasibility is studied from the numerical investigation with simple and multiple damages detection. It is concluded that the sophisticated damage conditions need much longer time to detect successfully.
8
Carminati, M., and S. Ricci. "Structural Damage Detection Using Nonlinear Vibrations." International Journal of Aerospace Engineering 2018 (September 25, 2018): 1–21. http://dx.doi.org/10.1155/2018/1901362.
Abstract:
Nonlinear vibrations emerging from damaged structures are suitable indicators for detecting defects. When a crack arises, its behavior could be approximated like a bilinear stiffness. According to this scheme, typical nonlinear phenomena as the presence of superharmonics in the dynamic response and the variation of the oscillation frequency in time emerge. These physical consequences give the opportunity to study damage detection procedures with relevant improvements with respect to the typical strategies based on linear vibrations, such as high sensitivity to small damages, no need for an accurate comparison model, and behavior not influenced by environmental conditions. This paper presents a methodology, which aims at finding suitable nonlinear phenomena for the damage detection of three contact-type damages in a panel representing a typical aeronautical structural component. At first, structural simulations are executed using MSC Nastran models and reduced dynamic models in MATLAB in order to highlight relevant nonlinear behaviors. Then, proper experimental tests are developed in order to look for the nonlinear phenomena identified: presence of superharmonics in the dynamic response and nonlinear behavior of the lower frequency of vibration, computed using the CWT (continuous wavelet transform). The proposed approach exhibits the possibility to detect and localize contact-type damages present in a realistic assembled structure.
9
Xu, Tao, Yihang Zhu, Xiaomin Zhang, Zheyuan Wu, and Xiuqin Rao. "Dynamic Prediction Model for Initial Apple Damage." Foods 12, no. 20 (October 11, 2023): 3732. http://dx.doi.org/10.3390/foods12203732.
Abstract:
Prediction models of damage severity are crucial for the damage expression of fruit. In light of issues such as the mismatch of existing models in actual damage scenarios and the failure of static models to meet research needs, this article proposes a dynamic prediction model for damage severity throughout the entire process of apple damage and studies the relationship between the initial bruise form and impact energy distribution of apple damage. From the experiments, it was found that after impact a “cell death zone” appeared in the internal pulp of the damaged part of Red Delicious apples. The reason for the appearance of the cell death zone was that the impact force propagated in the direction of the fruit kernel in the form of stress waves; the continuous action of which continuously compressed the pulp’s cell tissue. When the energy absorbed via elastic deformation reached the limit value, intercellular disadhesion of parenchyma cells at the location of the stress wave peak occurred to form cell rupture. The increase in intercellular space for the parenchyma cells near the rupture site caused a large amount of necrocytosis and, ultimately, formed the cell death zone. The depth of the cell death zone was closely related to the impact energy. The correlation coefficient r between the depth of the cell death zone and the distribution of impact energy was slightly lower at the impact height of 50 mm. As the impact height increased, the correlation coefficient r increased, approaching of value of 1. When the impact height was lower (50 mm), the correlation coefficient r had a large distribution range (from 0.421 to 0.983). As the impact height increased, the distribution range significantly decreased. The width of the cell death zone had a poor correlation with the pressure distribution on the impact surface of the apples that was not related to the impact height. In this article, the corresponding relationship between the form and impact energy distribution of the internal damaged tissues in the initial damage of Red Delicious apples was analyzed. This analysis aimed to provide a research concept and theoretical basis for more reliable research on the morphological changes in the damaged tissues of apples in the future, further improving the prediction accuracy of damage severity.
10
Capozucca, R., E. Magagnini, and M. V. Vecchietti. "Experimental Free Vibration of Damaged RC Beam Models." Key Engineering Materials 827 (December 2019): 499–504. http://dx.doi.org/10.4028/www.scientific.net/kem.827.499.
Abstract:
Reinforced Concrete (RC) Beam undamaged and damaged were investigated by free vibration to obtain a variation of frequency values at different degree of damage. Experimental tests were carried out on RC beams in scale and in real scale. The damage of RC beams in real scale was obtained by cracking under static bending tests, while in the case of beam in scale is obtained by notches on the concrete cover with different width. In general, the effects on the dynamic response of diffused damages and of concentrated damages on a section of beam have been experimentally analyzed. The envelope of frequency response functions (FRFs) obtained by dynamic experimental tests was elaborated and the changes of natural frequency values were then correlated to the damage degree of RC beams. The experimental data have been discussed and analyzed by comparison with theoretical results.
11
Dimri, Akshat, and Sushanta Chakraborty. "Experimental Investigation on Damage Sensitive Dynamic Responses of a Reinforced Concrete Beam." Proceedings of the 12th Structural Engineering Convention, SEC 2022: Themes 1-2 1, no. 1 (December 19, 2022): 1019–23. http://dx.doi.org/10.38208/acp.v1.615.
Abstract:
Reinforced concrete structures are subjected to damage due to environmental loading and operational conditions. Early detection of damages in reinforced concrete structures is very important. However, this becomes difficult because failure at the micro level in the form of minute cracks, develops much earlier than the visual appearance of actual damages resulting out of coalesce of several such micro level damages. Vibration based damage detection techniques, particularly use of modal testing by exciting a structure dynamically and measuring resulting responses is well established in current practice. Still, real experimental investigation involving a full scale reinforced concrete structure is somewhat rare in current literature. In the present investigation, dynamic responses of a 3.3-metre long reinforced concrete beam were measured experimentally before and after damage. Damage in the form of flexural cracks was inflicted by applying quasi-static load using a universal testing machine of capacity 300 kN under the four-point bending configuration. Broadband roving impact excitation was imparted through an impact hammer and the resulting responses were picked up by a single accelerometer. The time signals of both the force and acceleration responses were Fourier transformed using a spectrum analyser to determine the frequency response functions. The modal parameters e.g. frequencies, mode shapes, modal damping factors are found out through curve fitting. The frequency response function at a particular point has also been investigated for all the load increments and gradual changes into the dynamic properties are noted. Comparison of modal parameters between the undamaged and damaged state including their curvatures indicates that they are sensitive to the crack locations. On the other hand, the differences in frequency response functions including their curvatures were sensitive to the damage intensity in turn. The current experimental investigation provides great insight into the application of vibration-based damage detection technique to reinforced concrete structures.
12
Wang, Feng, Haibo Wang, Ying Xu, Bing Cheng, and Qianqian Wang. "Analysis of Energy Dissipation Characteristics of Damaged Sandstone under Impact Load." Shock and Vibration 2021 (July 22, 2021): 1–10. http://dx.doi.org/10.1155/2021/4200452.
Abstract:
Before rock burst, coal, and gas outburst dynamic load, rock mass in geotechnical engineering has been an indifferent degree of damage. The dissipation energy of rock mass under dynamic load reflects the difficulty of rock breaking. In view of the energy dissipation of damaged rock mass under dynamic load, the cyclic loading and unloading test is carried out to make sandstone in different damage states, and the damage degree of sandstone is characterized by the change of longitudinal wave velocity before and after cyclic loading and unloading. Then, the rock with different damage degrees is tested by adopting the split Hopkinson pressure bar (SHPB). Finally, the energy dissipation characteristics of damaged rock under impact load are analyzed. The results show that the damage factor of sandstone increases with the increase of the upper limit of stress after cyclic static loading. The dynamic strength and peak strain of damaged sandstone increase with the increase of impact pressure and decrease with the increase of damage degree. With the increase of damage degree of sandstone, the reflection energy and dissipation energy of sandstone increase, while the transmission energy decreases.
13
Pattavanitch, Jitti, Puttha Jeenkour, and Kittipong Boonlong. "Cooperative Coevolution with Dynamic Species-Size Strategy for Vibration-Based Damage Detection in Plates." International Journal of Advanced Research in Engineering 3, no. 3 (September 27, 2017): 12. http://dx.doi.org/10.24178/ijare.2017.3.3.12.
Abstract:
Vibration-based damage detection is based on the fact that vibration characteristics such as natural frequencies and mode shapes of structures are changed when the damage occurs. This paper proposes dynamic species-size strategy in cooperative coevolution concept. The resulting algorithm, cooperative coevolutionary genetic algorithm with dynamics species-size (CCGADSS), is used as the optimization algorithm in the vibration-based damage detection in plates. The objective function is numerically calculated from the difference between experimentally vibration characteristics and numerically evaluated vibration characteristics of the predicted damage. In finite element model for objective calculation, the plates are equally divided into 64 elements. There are 2 different cases with dissimilar occurred damage in plates are considered. In first case, the plate hase only one region consisting of 4 elements which are together connected and have same damage. In second case, there are 5 separated elements which are damaged differently. In order to demonstrate the performance of the dynamic species-size strategy, 3 optimization algorithms, which are genetic algorithm (GA), cooperative coevolutionary genetic algorithm (CCGA), and CCGADSS. The results indicate that CCGADSS is superior to GA and CCGA. Moreover solutions obtained using CCGADSS are quite close the actual damage. These results show that the dynamic species-size strategy can enhance performance of cooperative coevolution concept.
14
Zheng, Qiangqiang, Hao Hu, Anying Yuan, Mengyao Li, Haibo Wang, Mengxiang Wang, Qi Zong, and Shouyang Zhang. "Impact Dynamic Properties and Energy Evolution of Damaged Sandstone Based on Cyclic Loading Threshold." Shock and Vibration 2020 (November 27, 2020): 1–12. http://dx.doi.org/10.1155/2020/6615602.
Abstract:
Rocks in deep coal mines are usually in varying degrees of damage state before they are destabilized by impact loads such as rock bursts. For the problem of the mechanical properties and energy evolution of damaged rocks under impact loads, the authors use static loads with different cyclic load thresholds to act on sandstone specimens to make them in distinct degrees of damage. Then, the rock mechanics system (MTS-816) and the Split Hopkinson pressure bar (SHPB) are employed to perform uniaxial compression and impact dynamics tests on sandstones with different degrees of damage. The results show that, from the perspective of mechanical properties, the uniaxial compressive strength and dynamic compressive strength of the damaged sandstone gradually decrease with the increase of the upper limit of the cycle threshold and both obey the growth law of the quadratic function, and the dynamic strength increase factor (DIF) also decreases with the increase of the cyclic load threshold. In terms of energy, with the increment of the cyclic load threshold, the number of cracks in the damaged sandstone is large and the scale is enormous. Due to the effect of cracks, when the incident energy is a fixed value, the transmission energy decreases with the increase of the damage degree and the change law of the reflection energy is the opposite. The systematic study of the dynamic mechanical properties and energy evolution law of the damaged sandstone provides some reference for the prevention and mechanism research of rock bursts.
15
Wong, Simon C., and Alan A. Barhorst. "Polynomial Interpolated Taylor Series Method for Parameter Identification of Nonlinear Dynamic System." Journal of Computational and Nonlinear Dynamics 1, no. 3 (March 24, 2006): 248–56. http://dx.doi.org/10.1115/1.2209647.
Abstract:
This research work is in the area of structural health monitoring and structural damage mitigation. It addresses and advances the technique in parameter identification of structures with significant nonlinear response dynamics. The method integrates a nonlinear hybrid parameter multibody dynamic system (HPMBS) modeling technique with a parameter identification scheme based on a polynomial interpolated Taylor series methodology. This work advances the model based structural health monitoring technique, by providing a tool to accurately estimate damaged structure parameters through significant nonlinear damage. The significant nonlinear damage implied includes effects from loose bolted joints, dry frictional damping, large articulated motions, etc. Note that currently most damage detection algorithms in structures are based on finding changed stiffness parameters and generally do not address other parameters such as mass, length, damping, and joint gaps. This work is the extension of damage detection practice from linear structure to nonlinear structures in civil and aerospace applications. To experimentally validate the developed methodology, we have built a nonlinear HPMBS structure. This structure is used as a test bed to fine-tune the modeling and parameter identification algorithms. It can be used to simulate bolted joints in aircraft wings, expansion joints of bridges, or the interlocking structures in a space frame also. The developed technique has the ability to identify unique damages, such as systematic isolated and noise-induced damage in group members and isolated elements. Using this approach, not just the damage parameters, such as Young’s modulus, are identified, but other structural parameters, such as distributed mass, damping, and friction coefficients, can also be identified.
16
Liu, Yunqiu, Anqi Fu, Binsong Jiang, Liyuan Yu, and Xiaobing Wang. "Study on the Static and Dynamic Fracturing Properties of Marble after Being Damaged Dynamically." Advances in Civil Engineering 2020 (September 4, 2020): 1–13. http://dx.doi.org/10.1155/2020/8886198.
Abstract:
A split Hopkinson pressure bar (SHPB) system was first used to perform the cyclic impact loading tests on notched semicircular bend (NSCB) marble specimens. Then, static and dynamic three-point bending tests were conducted on these dynamically damaged specimens, respectively. In the cyclic impact loading tests, the dynamic elastic modulus decreases gradually as the impact number increases, but dynamic cumulative damage exhibits a growing trend. In the static and dynamic three-point bending tests, when dynamic cumulative damage is less than 0.345, the dynamic fracture toughness values are larger than the static fracture toughness values, but the experimental data exhibit the opposite results when dynamic cumulative damage ranges from 0.345 to 0.369. Through the quantitative analysis of fracture surface morphologies, the roughness and area of the fracture surfaces increase with an increasing dynamic cumulative damage. Under the same dynamic cumulative damage of the specimens, both the roughness and area of the surfaces fractured by static three-point bending are larger than those fractured by dynamic three-point bending.
17
ÖZCAN, Zeki, and Ömer SEMİZ. "DETERMINATION OF STRUCTURAL DAMAGE LEVELS BY USING DYNAMIC PARAMETERS." INTERNATIONAL REFEREED JOURNAL OF ENGINEERING AND SCIENCES, no. 16 (2022): 0. http://dx.doi.org/10.17366/uhmfd.2022.16.3.
Abstract:
Aim: This study revealed the relationship between the change in dynamic characteristics of structures damaged by exposure to extreme loads such as earthquakes, explosions, and impact and damage levels. Thus, a quick method can be used immediately after the damage has been proposed. Method: The studies consist of two parts, experimental measurements, and numerical solutions. For the analysis, a single degree of freedom, a four-column steel model structure was fabricated, and its free vibrations were recorded with the help of an accelerometer. Three scenarios are defined for the system no damage, medium damage, and heavy damage. Each of these failure scenarios is achieved by changing the boundary conditions of the columns. Results: The acceleration records were processed with the Seismosignal software, and the free vibration periods of the structure were determined for each case. In the numerical part of the study, free vibration periods of undamaged and damaged structures were calculated using the finite element method. Conclusion: It has been shown that the results obtained from the experimental and numerical methods are compatible. With the study, it has been revealed that damaged structures can be evaluated using free vibration periods.
18
Buravova, S. N., A. A. Goncharov, and Ju N. Kiselev. "Surface damage under dynamic loading." Tribology International 29, no. 5 (August 1996): 357–63. http://dx.doi.org/10.1016/0301-679x(95)00062-9.
19
Wang, Sheng Chun, Rong Sheng Shen, Tong Hong Jin, and Shi Jun Song. "Dynamic Behavior Analysis and its Application in Tower Crane Structure Damage Identification." Advanced Materials Research 368-373 (October 2011): 2478–82. http://dx.doi.org/10.4028/www.scientific.net/amr.368-373.2478.
Abstract:
First establish a dynamic model of tower crane in the load lifting process, the lifting load is solved.Then establish the FEM model of the tower crane under the normal and the damage condition. Get the dynamic displacement of the normal and the damage status under the lifting dynamic load. Propose a damaged diagnosis method by the displacement rate. The results of the study show that this method can not only diagnose the structural damage status, but also determine the positions of structural damage. This will be a new search on tower crane structural health diagnosis.
20
Zhang, Yunkai, Xixue Tan, Guohua Li, Jun Dong, Jingyi Guo, and Fanyue Liu. "Bridge Structure Damage Identification Based on Dynamic Characteristics." Coatings 12, no. 3 (February 25, 2022): 313. http://dx.doi.org/10.3390/coatings12030313.
Abstract:
With the increasing traffic volume and years of usage during the operation process, a bridge structure will experience aging and damage to different degrees, leading to the decline in bridge reliability and seriously affecting its operation safety. In this study, the bridge was abstracted into a beam structure for damage identification. Next, the influence of damage on the bridge structure was explored from the angles of its inherent frequency and displacement mode, respectively. Our results showed that whether the structure was damaged could be accurately judged by its inherent frequency, but the specific damage could not be further judged. Through the structural displacement curve, the rough range of structural damage could be judged; however, the damage could not be accurately positioned. The damage position could be accurately identified to some extent by taking the derivatives from the difference value of the structural displacement curve. The above conclusions were verified based on a double-span beam. We found that the above conclusions still held true for the double-span beam, thus proving their universality.
21
Li, Suzhen, and Zhishen Wu. "C21 Non-baseline damage location based on dynamic macro-strain measurements." Proceedings of the Symposium on the Motion and Vibration Control 2005.9 (2005): 449–54. http://dx.doi.org/10.1299/jsmemovic.2005.9.449.
22
Zhao, Han, Liang Chen, Guisheng Zhong, Yina Huang, Xulai Zhang, Cenfeng Chu, Lin Chen, and Ming Wang. "Titanium Dioxide Nanoparticles Induce Mitochondrial Dynamic Imbalance and Damage in HT22 Cells." Journal of Nanomaterials 2019 (April 30, 2019): 1–16. http://dx.doi.org/10.1155/2019/4607531.
Abstract:
Mitochondria, as dynamic organelles, are precisely regulated by fusion and fission. The dynamic balance of fusion and fission controls mitochondrial morphology and their subcellular location and function. Exposure to titanium dioxide nanoparticles (TiO2 NPs) may cause serious health problems. However, how TiO2 NPs affect the mitochondrial dynamics remains unclear. In the present study, we investigated the changes of mitochondrial dynamics in the TiO2NPs-treated HT22 cells by confocal and stimulated emission depletion (STED) microscopy. The confocal images demonstrated obvious changes in the average length and density of the mitochondria after TiO2 NPs treatment, while STED images further obtained the nanoscale submitochondrial structures of the mitochondria under TiO2 NPs insult. The fluorescence intensity distributions suggested that mitochondria fragmented in the TiO2 NPs-treated cells. TiO2 NPs treatment caused mitochondrial dynamic imbalance due to the imbalanced expression of dynamin-related protein 1 (Drp1) and optic atrophy 1 (Opa1). Furthermore, we examined the levels of oxidative stress and mitochondrial membrane potential (MMP) and the generation of adenosine triphosphate (ATP), which revealed the damage of mitochondria under TiO2 NPs exposure. Meanwhile, the significant changes of expressions of B-cell lymphoma 2-associated X protein (Bax), B-cell lymphoma 2 (Bcl-2), cytochrome c (Cyt C), and caspase 9 demonstrated that TiO2 NPs treatment activated the mitochondrial-related apoptosis pathway. These cellular events can be largely prevented via cell incubation with mitoTEMPO, a mitochondria-targeted superoxide scavenger. Our results confirm that TiO2 NPs targeted the mitochondria, inducing mitochondrial dynamic imbalance and damage in HT22 cells. Our study provides an insightful understanding of the mechanisms underlying TiO2 NPs cytotoxicity.
23
Su, Tian, Wei Su, Chenyu Du, Zhanfang Huang, Jianping Dong, and Chao Hu. "Damage identification of wind turbine blades based on dynamic characteristics." Nonlinear Engineering 11, no. 1 (January 1, 2022): 47–57. http://dx.doi.org/10.1515/nleng-2022-0007.
Abstract:
Abstract In this article, the Ansys Workbench was used to carry out the finite element analysis of 15 kW wind turbine blades with different damaged positions and different damaged degrees. The results show that the change rate of natural frequency, displacement modes, and strain modes of the blades increased with the increase in the damage degree; the change rate of the natural frequency and displacement modes of the blade decreased with the increase in the speed, while the change rate of the strain modes increased; the change allocation ratio of the displacement modes and strain modes after the damage was more obvious at the damage location than other positions, which can be used to locate the damage position of the blade; the change allocation ratio of strain modes is higher than the change allocation ratio of displacement modes when the damage degree is the same, which means that the recognition effect of the strain modes is more significant than that of the displacement modes.
24
Zhong, Ju Fang, Zhi Peng Fan, Luo Long Zhan, and Jun Wei Liang. "Reinforced Concrete Frame Structure Dynamic Analysis Based on SAP2000." Applied Mechanics and Materials 744-746 (March 2015): 211–16. http://dx.doi.org/10.4028/www.scientific.net/amm.744-746.211.
Abstract:
Structure under long-term load, environmental erosion, material aging, especially under the seismic action can cause damage accumulation and bearing capacity decrease. In order to make sure its safety and reliable, avoid extreme cases of catastrophic accident, it is necessary to carry out the engineering structural health diagnosis. Using SAP2000 software, seismic response analysis for a two layer reinforced concrete frame structure is carried out. The laws of the acceleration response time history and spectrum under different seismic action were found out by discussing structure in no damage and different damages. The results showed that no matter where the damage located, the top node response increment is bigger than the middle node, the peak of acceleration response spectrum changes little with the beam damage degrees changing. Selecting the acceleration response peak of the top node as a structural damage index is feasible in the damage detection and identification of engineering structures, but analyzing the response spectrum for damage detection is unpractical.
25
Zenkov, Solon. "Localization of structural damage based on its dynamic analysis." Transactions of the Krylov State Research Centre, SPECIAL ISSUE 1 (April 16, 2019): 170–76. http://dx.doi.org/10.24937/2542-2324-2019-1-s-i-170-176.
Abstract:
This paper gives the results of analytical and experimental data on localization of structural damage, obtained through comparison of vibration modes for intact and damaged structure. The paper studies a standard dog-bone sample used for highcycle fatigue tests, the analysis being performed for its finite-element model. Necking damage of the sample was simulated by step-by-step elimination of elements from the model. Physical tests were performed as per the same approach. This paper studies the following damage localization methods: direct method of shape variation; shape curvature method and damage index method. The analysis of vibration shapes performed as per various approaches yielded damage locations and made it possible to identify the most accurate of above-mentioned methods.
26
Duvnjak, Ivan, Domagoj Damjanović, Marko Bartolac, and Ana Skender. "Mode Shape-Based Damage Detection Method (MSDI): Experimental Validation." Applied Sciences 11, no. 10 (May 18, 2021): 4589. http://dx.doi.org/10.3390/app11104589.
Abstract:
The main principle of vibration-based damage detection in structures is to interpret the changes in dynamic properties of the structure as indicators of damage. In this study, the mode shape damage index (MSDI) method was used to identify discrete damages in plate-like structures. This damage index is based on the difference between modified modal displacements in the undamaged and damaged state of the structure. In order to assess the advantages and limitations of the proposed algorithm, we performed experimental modal analysis on a reinforced concrete (RC) plate under 10 different damage cases. The MSDI values were calculated through considering single and/or multiple damage locations, different levels of damage, and boundary conditions. The experimental results confirmed that the MSDI method can be used to detect the existence of damage, identify single and/or multiple damage locations, and estimate damage severity in the case of single discrete damage.
27
ALEKSEYTSEV, A. V., and M. D. ANTONOV. "DYNAMICS OF REINFORCED CONCRETE NON-BEAM FRAMES IN CASE OF DAMAGE TO SLABS PUNCHING." Building and reconstruction 96, no. 4 (2021): 23–34. http://dx.doi.org/10.33979/2073-7416-2021-96-4-23-34.
Abstract:
An approach to the assessment of dynamic effects for reinforced concrete non-beam frames of structures under combined emergency actions is considered. Primary impacts imply an excess of operational loads, which causes damage to the slab-column junction from punching to the onset of a secondary impacts. Secondary impacts include considering the removal of any column from the design model over a finite time. The analysis of dynamic effects based on two approaches: the first is based on the energy method of G.A. Geniev and assumes a quasi-static assessment of the stress-strain state of the damaged system; the second is the analysis of the transient dynamic process taking into account physical and geometric nonlinearity. An approximate approach to modeling the damage of a reinforced concrete slab from punching is proposed and further prospects for its improvement are considered. The degree of danger at emergency impacts for structures pre-damaged by punching, as well as the influence of these damages on the survivability of frames under these effects, has been established. An example of assessing survivability on a model of an underground parking frame in the presence of damage from punching for one of the column-slab joints is considered.
28
Yan, Qiushi. "Numerical Simulation of a Subway Station Structure Subjected to Terrorism Bombing." Open Civil Engineering Journal 9, no. 1 (September 10, 2015): 688–92. http://dx.doi.org/10.2174/1874149501509010688.
Abstract:
Subway stations are important means of transportation and main targets attacked by terrorists. In order to study the subway station response and damage subjected to blast loading, numerical simulation is carried out to estimate a subway station in beijing. An “explosive-air-structure ” dynamic interactive numerical model is built for the blast dynamic analysis of subway station subjected to blast. The patterns of damage about column are compared in different charges of explosive. The damages of concrete and reforcing bar in column are discussed. Although the column near the explosive is destoried under the charge of 30kg TNT, The calculations showns that it’s safe for the subway station to subject to blast loading under the charge of 30kg TNT. The local damage of column influence collapse of the station little. The dynamtic response of the structure is given to support the protection on the subway station against terrorism bombing.
29
Mei, Song-hua, Xu-li Liang, Lei Wen, and Zi-long Kou. "Experimental Study on Mechanical Properties of Freeze-Thaw Damaged Red Sandstone under Combined Dynamic and Static Loading." Shock and Vibration 2021 (November 11, 2021): 1–14. http://dx.doi.org/10.1155/2021/9980549.
Abstract:
Using the freeze-thaw cycle test chamber, the red sandstone samples are subjected to cyclic freeze-thaw tests. The physical properties, static mechanical properties of freeze-thaw damage rocks, and the compressional wave velocity at specific axial pressure are measured using conventional physical tests and uniaxial compression tests. The mechanical properties of freeze-thaw damage rocks under dynamic and static loading were studied using Hopkinson pressure bar which can exert axial pressure. The studies show that, with the increase of freeze-thaw cycles, the surface layer of the rock sample undergoes spalling phenomenon, the weight gradually decreases, the sample compactness becomes worse, there are microcracks between the cemented particles, and the compressive strength and elastic modulus decrease. Under the static loading, the longitudinal wave velocity of freeze-thaw damaged samples change significantly compared with that of samples without freeze-thaw. The freeze-thaw damage degree, axial pressure, and strain rate are coupled with each other, which together affect the dynamic mechanical properties of samples, and make the variation of mechanical parameters, such as dynamic peak strength and dynamic elastic modulus of rock. The combined action of freeze-thaw damage and axial pressure weakens the strain rate effect of samples, but when the incident wave of SHPB test is same, the dynamic strength and elastic modulus of freeze-thaw damaged samples are reduced compared with those without freeze-thaw. Combining with strain equivalence principle, the constitutive relation of freeze-thaw damage of red sandstone under dynamic and static combined loading can reflect the influence of coupling damage of axial pressure and freeze-thaw, dynamic impact parameters, and other factors, which are in good agreement with the test results.
30
Morassi, Antonino, and Luigi Rocchetto. "A Damage Analysis of Steel-Concrete Composite Beams Via Dynamic Methods: Part I. Experimental Results." Journal of Vibration and Control 9, no. 5 (May 2003): 507–27. http://dx.doi.org/10.1177/1077546303009005002.
Abstract:
This paper is an experimental investigation on damage-induced changes in modal parameters of steel-concrete composite beams subject to small vibrations. Dynamic tests have been performed on two pairs of composite beams, whose connections have different linear densities, and three damage configurations for each beam have been analyzed. Damage was induced by removing concrete around some elements connecting the steel beam and the reinforced concrete slab and consequently causing a lack of structural solidarity between the two beams. Experiments revealed that: (i) unlike axial frequencies, flexural frequencies show a rather high sensitivity to damage and therefore can be considered as a valid indicator upon a diagnostic analysis; (ii) induced damage causes the nodes of flexural vibration modes to displace towards the damaged area; (iii) in addition to hindering relative sliding on the concrete-steel interface, the elements connecting the slab and the metallic beam play a key role in reducing transversal motions between the two beams. These experimental results were crucial to outline an accurate analytical model of the dynamic behavior of composite beams with damaged connectors and to formulate a diagnostic problem from dynamic test data. Part II of this research will deal with mechanical modeling of damaged composite beams and damage identification.
31
Cheng, Yuqiang, and Jianjun Wu. "Particle swarm algorithm-based damage-mitigating control law analysis and synthesis for liquid-propellant rocket engine." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 233, no. 10 (October 31, 2018): 3810–18. http://dx.doi.org/10.1177/0954410018806080.
Abstract:
The damage-mitigating control is a novel technique to ameliorate the reliability and safety of liquid-propellant rocket engines by achieving an optimized trade-off level between overall dynamic performance of the liquid-propellant rocket engine and structural durability of some selected critical damageable components under the condition of no impact on the achievement of the launch and flight mission. Thus, it is needed to be solved for the damage-mitigating control that the global optimization of the best trade-off between the damage of the critical damageable components and the performance of rocket engine. The major challenge should focus on: (i) to construct model of a certain rocket engine system dynamics, critical components structural dynamics, and damage dynamics; (ii) to optimize open loop feed-forward control law based on liquid-propellant rocket engine system dynamic model, structural and damage dynamics model, by using particle swarm optimization algorithm; (iii) to synthesize an intelligent damage-mitigating control system using the optimized open loop control law. In this paper, synthesis procedure of damage mitigation is introduced; structure and damage dynamic model of damageable components are formulated. The results of the simulation computation show that the synthesized control laws are implemented and achieve the effect of damage mitigating for the liquid-propellant rocket engine. It can provide important theoretical and practical value not only for improving the safety and reliability of the liquid-propellant rocket engine, but also for the complex thermo-flow-mechanical systems such as airplane engines, automobile engines, and fossil-fueled power plant because their service life is very critical too.
32
Cao, Li Lin, Ai Qun Li, and Yang Deng. "Experimental Research on Structural Damage Alarming of Benchmark Structure Based on Empirical Mode Decomposition." Advanced Materials Research 243-249 (May 2011): 61–66. http://dx.doi.org/10.4028/www.scientific.net/amr.243-249.61.
Abstract:
A structural damage alarming method is proposed using empirical mode decomposition. The basic idea of this method is that with respect to the intact model and damaged models, the energy redistribution of the intrinsic mode functions decomposed from the structural response can represent the variation of the structural dynamic characteristics caused by the structural damage. By taking the Benchmark test model as the research object, the structural dynamic responses from the hammer-impact tests are collected then the damage alarming parameters and the damage alarming indices are evaluated. The experimental results reveal that the structural damage alarming indices based on empirical mode decomposition is able to effectively detect the structural initial damage with preferable damage alarming capacity.
33
Ikura, Masae, Kanji Furuya, Atsuhiko Fukuto, Ryo Matsuda, Jun Adachi, Tomonari Matsuda, Akira Kakizuka, and Tsuyoshi Ikura. "Coordinated Regulation of TIP60 and Poly(ADP-Ribose) Polymerase 1 in Damaged-Chromatin Dynamics." Molecular and Cellular Biology 36, no. 10 (March 14, 2016): 1595–607. http://dx.doi.org/10.1128/mcb.01085-15.
Abstract:
The dynamic exchange of histones alleviates the nucleosome barrier and simultaneously facilitates various aspects of cellular DNA metabolism, such as DNA repair and transcription. In response to DNA damage, the acetylation of Lys5 in the histone variant H2AX, catalyzed by TIP60, plays a key role in promoting histone exchange; however, the detailed molecular mechanism still is unclear. Here, we show that the TIP60 complex includes poly(ADP-ribose) polymerase 1 (PARP-1). PARP-1 is required for the rapid exchange of H2AX on chromatin at DNA damage sites. It is known that PARP-1 binds dynamically to damaged chromatin and is crucial for the subsequent recruitment of other repair factors, and its auto-poly(ADP-ribosyl)ation is required for the dynamics. We also show that the acetylation of histone H2AX at Lys5 by TIP60, but not the phosphorylation of H2AX, is required for the ADP-ribosylation activity of PARP-1 and its dynamic binding to damaged chromatin. Our results indicate the reciprocal regulation of K5 acetylation of H2AX and PARP-1, which could modulate the chromatin structure to facilitate DNA metabolism at damage sites. This could explain the rather undefined roles of PARP-1 in various DNA damage responses.
34
Mohan, Poonam, and A. P. Shashikala. "Numerical Investigation on Flood Water Sloshing Influence on Intact and Damaged Stability of Ship." WSEAS TRANSACTIONS ON APPLIED AND THEORETICAL MECHANICS 16 (January 12, 2022): 261–73. http://dx.doi.org/10.37394/232011.2021.16.29.
Abstract:
Sloshing affects the intact and damage stability of the ship, which causes variation in dynamic metacentric height (GM) under critical load conditions. The transient flooding soon after the ship damage is analyzed, with floodwater accumulation in large space and causing the ship to suffer huge heel angles. The ship motion and stability changes when sloshing becomes high in partially flooded compartments. Most of the previous researches focus on the motion response of ship alone, hence the variation of stability due to sloshing is to be more critically studied. In the present study, three critical damage locations are identified and flooding through these locations are analyzed using the volume of fluids method. The method focus on finding damage ship motion response, flood water dynamics, and coupled dynamics of both. This is studied using the numerical method FLOW3D. Motion and stability behaviour will be different for different damage locations; hence portside, starboard-side, and aft-end bottom damage cases are considered. The effect of compartment shape and damage location on motion response and stability of the damaged ship is highlighted.
35
Wang, Feifei, Jinggan Shao, Wenkai Li, Longfei Wang, Yafei Wang, and Honglin Liu. "Numerical Simulation Study on Lining Damage of Shield Tunnel under Train Load." Sustainability 14, no. 21 (October 27, 2022): 14018. http://dx.doi.org/10.3390/su142114018.
Abstract:
Under the long-term dynamic load influence of trains, shield tunnel structures are damaged. With the increase in operating number, cumulative damage gradually increases. When cumulative damage increases to a certain value, the tunnel lining produces cracks and loses tensile strength, which leads to tunnel deformation, damage, etc. In serious cases, the tunnel ceases operation, causing traffic accidents and casualties. Based on the finite element software ABAQUS, this paper analyses the change rule of tunnel lining damage under long-term dynamic train load and explores the influence of tunnel buried depth on the change rule of tunnel lining damage. The excitation force function is used to generate a series of dynamic and static loads superimposed by sine functions to simulate the dynamic loads of trains. Load is applied above the tunnel by writing DLOAD subprogram. The results show that the damage of tunnel lining mainly occurs at the arch foot and the structural damage in other places can be neglected. Under the same loading condition, the greater the tunnel lining damage is. Under the same loading conditions, the tunnel lining damage increases with the increase in buried depth. According to the test results, the mathematical expressions of cumulative damage value versus loading times at the location prone to fatigue damage. It provides theoretical reference for safety evaluation and protection of tunnel structure under long-term train load.
36
Li, Sheng Long, Liang Gao, and He Zhang. "Research on the Optimization Method of the Friction Plate Backlash." Key Engineering Materials 572 (September 2013): 476–79. http://dx.doi.org/10.4028/www.scientific.net/kem.572.476.
Abstract:
Friction plate, the key part of the planetary transmission, is often damaged by the impact of the geer mesh. And the reason of the impact damage is not known yet. The backlash of the friction plate is crucial to the impact damage, thus the relationship of the backlash and impact damage is dissgussed in this study.The mathematic model is built up to calculate the impact force and the ADAMS dynamics simulation software is used to check the result of the mathematic model and get the dynamic characteristics of the impact force and provide the basis for the optimizing of backlash. Keywords: friction plate;impact of geer mesh;geer backlash;mathematic model
37
Yatom, H., and R. Ruppin. "Dynamic fragmentation model with internal damage." Journal of Applied Physics 65, no. 1 (January 1989): 112–16. http://dx.doi.org/10.1063/1.343408.
38
Haritos, N., and E. Abu-Aisheh. "Damage Detection Using Dynamic Testing Techniques." Australian Journal of Structural Engineering 4, no. 1 (January 2002): 41–49. http://dx.doi.org/10.1080/13287982.2002.11464906.
39
Bourne, N. K., S. Parry, D. Townsend, P. J. Withers, C. Soutis, and C. Frias. "Dynamic damage in carbon-fibre composites." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 374, no. 2071 (July 13, 2016): 20160018. http://dx.doi.org/10.1098/rsta.2016.0018.
Abstract:
The Taylor test is used to determine damage evolution in carbon-fibre composites across a range of strain rates. The hierarchy of damage across the scales is key in determining the suite of operating mechanisms and high-speed diagnostics are used to determine states during dynamic loading. Experiments record the test response as a function of the orientation of the cylinder cut from the engineered multi-ply composite with high-speed photography and post-mortem target examination. The ensuing damage occurs during the shock compression phase but three other tensile loading modes operate during the test and these are explored. Experiment has shown that ply orientations respond to two components of release; longitudinal and radial as well as the hoop stresses generated in inelastic flow at the impact surface. The test is a discriminant not only of damage thresholds but of local failure modes and their kinetics. This article is part of the themed issue ‘Multiscale modelling of the structural integrity of composite materials’.
40
Deng, H., and S. Nemat-Nasser. "Dynamic damage evolution in brittle solids." Mechanics of Materials 14, no. 2 (December 1992): 83–103. http://dx.doi.org/10.1016/0167-6636(92)90008-2.
41
Pijaudier-Cabot, Gilles, and Zdeněk P. Bažant. "Dynamic stability analysis with nonlocal damage." Computers & Structures 29, no. 3 (January 1988): 503–7. http://dx.doi.org/10.1016/0045-7949(88)90403-8.
42
Zimmerman, David C., Hyoung M. Kim, Theodore J. Bartkowicz, and Mohamed Kaouk. "Damage Detection Using Expanded Dynamic Residuals." Journal of Dynamic Systems, Measurement, and Control 123, no. 4 (December 25, 2000): 699–705. http://dx.doi.org/10.1115/1.1410932.
Abstract:
In this work, an algorithm for detecting the location of damage in a structure using a finite element model and pre- and post-damage measured modal properties is presented. In particular, an algorithm which addresses one aspect of the incomplete measurement problem, namely the measurement of mode shape information at fewer spatial degrees of freedom than that modeled in the finite element model, is presented. The performance of the algorithm is evaluated using the NASA 8-bay experimental test bed. The results indicate that the proposed approach holds great promise for identifying damage when structural instrumentation is limited. The same approach can also be used in model correlation efforts to aid in the selection of physical parameters to be estimated.
43
Zhu, Hong, Ge Fu, Yu-Cai Feng, and Kevin Lü. "Dynamic Damage Recovery for Web Databases." Journal of Computer Science and Technology 25, no. 3 (May 2010): 548–61. http://dx.doi.org/10.1007/s11390-010-9344-y.
44
ZHU, XINQUN, and HONG HAO. "DAMAGE DETECTION OF RC SLABS USING NONLINEAR VIBRATION FEATURES." International Journal of Structural Stability and Dynamics 09, no. 04 (December 2009): 687–709. http://dx.doi.org/10.1142/s0219455409003247.
Abstract:
Studied herein are the signatures of nonlinear vibration characteristics of damaged reinforced concrete structures using the wavelet transform (WT). A two-span RC slab built in 2003 was tested to failure in the laboratory. Vibration measurements were carried out at various stages of structural damage. The vibration frequencies, mode shapes, and damping ratios at each loading stage were extracted and analyzed. It is found that the vibration frequencies are not sensitive to small damages, but are good indicators when damage is severe. The dynamic responses are also analyzed in the time–frequency domain by WT and the skeleton curve is constructed to describe the nonlinear characteristics in the reinforced concrete structures. The results show that the skeleton curves are good indicators of damage in the reinforced concrete structures because they are more sensitive to small damages than vibration frequencies.
45
Minhas, Zill-e. Hasnain, and Sun Qin. "Evolution of the Coefficient of Dynamic Viscosity with Growing Damage in Metals." Applied Mechanics and Materials 313-314 (March 2013): 72–76. http://dx.doi.org/10.4028/www.scientific.net/amm.313-314.72.
Abstract:
Coefficient of dynamic viscosity (η) for uniaxial rectangular bar of steel is calculated using creep simulation in Ansys. Norton Secondary creep law with coefficients at 600 ᵒC is used. Steel bar is then inflicted with some damage elements in order to investigate the evolution of dynamic viscosity for varying degree of fatigued specimen at constant rate and temperature. Isotropic damage parameter (D) based on the volume fraction of damaged elements is used to formulate a linear relation between the coefficient of viscosity and D. It is found that with 0.001 increase is damage parameter (D), almost 0.6% decrease on the value of Coefficient of dynamic viscosity (η) is observed.
46
Biswas, S., P. K. Datta, and C. D. Kong. "Static and dynamic instability characteristics of curved laminates with internal damage subjected to follower loading." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 225, no. 7 (May 17, 2011): 1589–600. http://dx.doi.org/10.1177/0954406211399977.
Abstract:
This article deals with the study of vibration, buckling, and dynamic instability characteristics in damaged cross-ply and angle-ply curved laminates under uniform, uniaxial follower loading, using finite element approach. First-order shear deformation theory is used to model the doubly curved panels and is formulated according to Sandars' first approximation. Damage is modelled using an anisotropic damage formulation. Analysis is carried out on plate and three types of curved panels to obtain vibration, buckling, and dynamic instability (flutter) behaviour. The effect of damage on natural frequency, critical buckling load, flutter load, and flutter frequency is studied. The results show that the introduction of damage influences the flutter characteristics of panels more profoundly than the free-vibration or buckling characteristics. The results also indicate that, compared to undamaged panels, heavily damaged panels show steeper deviations in stability characteristics than mildly damaged ones.
47
Makarov, N. S. "EXPERIMENTAL SETUP FOR DYNAMIC LOADING TIME-CONTROLLED." Problems of Strength and Plasticity 84, no. 4 (2023): 565–72. http://dx.doi.org/10.32326/1814-9146-2023-85-4-565-572.
Abstract:
The occurrence and development of damage in concrete and other brittle materials subjected to mechanical loads of varying intensity and duration, at the macroscopic level manifests itself in the form of cracking and fragmentation and makes a significant contribution to the load-bearing capacity of structures. To quantify the strength degradation of the damaged material, a scalar damage parameter is often used. Experimental investigation of the damage accumulation process under high-speed dynamic loads requires a tool that allows stopping the deformation process of a specimen at a given strain rate at a given strain magnitude. The proposed work is devoted to the problem of experimental study of damage accumulation process in brittle materials. Some common models used to predict the processes of dynamic deformation and fracture of concrete taking into account damage under loading are described. An experimental setup realizing a modification of the Kola method is developed to obtain the specified degrees of deformation of the specimen at different strain rates. Several load shaping schemes are considered. Two schemes allow limiting the deformation of the specimen in the experiment by adjusting the duration of the loading pulse, and one scheme allows limiting the deformation of the specimen due to the presence of a rigid ring surrounding the specimen. The processes of load formation and dynamic deformation of the specimen under the action of this load were analyzed using the following methods.
48
Algolfat, Amna, Weizhuo Wang, and Alhussein Albarbar. "The Sensitivity of 5MW Wind Turbine Blade Sections to the Existence of Damage." Energies 16, no. 3 (January 28, 2023): 1367. http://dx.doi.org/10.3390/en16031367.
Abstract:
Due to the large size of offshore wind turbine blades (OWTBs) and the corrosive nature of salt water, OWTs need to be safer and more reliable that their onshore counterparts. To ensure blade reliability, an accurate and computationally efficient structural dynamic model is an essential ingredient. If damage occurs to the structure, the intrinsic properties will change, e.g., stiffness reduction. Therefore, the blade’s dynamic characteristics will differ from those of the intact ones. Hence, symptoms of the damage are reflected in the dynamic characteristics that can be extracted from the damaged blade. Thus, damage identification in OWTBs has become a significant research focus. In this study, modal model characteristics were used for developing an effective damage detection method for WTBs. The technique was used to identify the performance of the blade’s sections and discover the warning signs of damage. The method was based on a vibration-based technique. It was adopted by investigating the influence of reduced blade element rigidity and its effect on the other blade elements. A computational structural dynamics model using Rayleigh beam theory was employed to investigate the behaviour of each blade section. The National Renewable Energy Laboratory (NREL) 5MW blade benchmark was used to demonstrate the behaviour of different blade elements. Compared to previous studies in the literature, where only the simple structures were used, the present study offers a more comprehensive method to identify damage and determine the performance of complicated WTB sections. This technique can be implemented to identify the damage’s existence, and for diagnosis and decision support. The element most sensitive to damage was element number 14, which is NACA_64_618.
49
Cheng, Cheng, Zhen Hua Nie, and Hong Wei Ma. "Structural Damage Detection of the Simple Beam Based on Responses Phase Space." Advanced Materials Research 605-607 (December 2012): 989–95. http://dx.doi.org/10.4028/www.scientific.net/amr.605-607.989.
Abstract:
In this paper, the technology of attractor phase space in chaotic theory is introduced and applied in the structural damage detection. Firstly the phase plane is constructed with the displacement and acceleration responses. Using the changes of phase plane topology of intact and damaged responses, a new damage index is extracted, and the structural damage existence and severity are identified successfully. Since some of the state variables can not be measured, a method of phase space reconstruction is proposed using single dynamic response. The dynamic responses are directly displayed into phase space, realizing transforming the signals from time domain to space domain. Then using the reconstructed phase space, the damage is diagnosed. The results indicate that the phase space reconstruction method has good robustness to noise, and higher sensitivity compared with traditional modal-based methods. The phase space reconstruction method can calculate the value of the damage index using single dynamic response, so that a single sensor can monitor structural damage existence and severity.
50
Yam, L. H., Li Cheng, Z. Wei, and Y. J. Yan. "Damage Detection of Composite Structures Using Dynamic Analysis." Key Engineering Materials 295-296 (October 2005): 33–38. http://dx.doi.org/10.4028/www.scientific.net/kem.295-296.33.
Abstract:
A study on the use of modal parameter analysis for damage detection of structures made of composites is conducted. The damage-induced variations of modal parameters are investigated both numerically and experimentally. An appropriate finite element model is proposed to analyze the dynamic characteristics of different types of structures made of composites, such as honeycomb sandwich plates and multi-layer composite plates, with internal cracks and delamination. The numerical results are in good agreement with experimental results available in the literature. Natural frequencies, modal displacements, strains and energy are analyzed for the determination of damage severity and location. Vibration measurements are carried out using piezoelectric patch actuators and sensors for comparison and verification of the FEM model proposed in this study. Energy spectrum for wavelet packets decomposition of structural dynamic responses is used to highlight the features of damaged samples. The mechanism of mode-dependent energy dissipation of composite plates due to delamination is revealed for the first time. Experimental results clearly show the dependence of changes of modal parameters on damage size and location. The results obtained in this study show that the measured modal damping change combined with the computed modal strain energy distribution can be used to determine the location of delamination in composite structures. Both numerical and experimental findings in this study are significant to the establishment of guideline for size and location identification of damage in composite structures.