Journal articles: 'Strain energy methods'

1

McDaniel, J. G., and J. H. Ginsberg. "Fundamental Tests of Two Modal Strain Energy Methods." Journal of Vibration and Acoustics 118, no. 2 (April 1, 1996): 272–75. http://dx.doi.org/10.1115/1.2889659.

Full text

APA, Harvard, Vancouver, ISO, and other styles

2

Li, Li, Yujin Hu, and Xuelin Wang. "Numerical methods for evaluating the sensitivity of element modal strain energy." Finite Elements in Analysis and Design 64 (February 2013): 13–23. http://dx.doi.org/10.1016/j.finel.2012.09.006.

Full text

APA, Harvard, Vancouver, ISO, and other styles

3

Ma, Hang, Ping Lu, Tao Jiang, Sheng Feng Shi, Jian Bin Wei, and Jing Bo Duan. "Research on Feasibility and Applicability of Delamination Localization Methods for Composite Laminated Beams." Applied Mechanics and Materials 599-601 (August 2014): 92–95. http://dx.doi.org/10.4028/www.scientific.net/amm.599-601.92.

Full text

Abstract:

The feasibility and applicability of delamination damages localization methods with various defined damage indexes for the damaged composite laminated beam were studied. The results indicate that, for the modal strain energy method, damage indexes defined by strain energy difference are more effective to locate the delamination damage than that of strain energy ratio. For energy response method, damage index defined by the second difference can effectively locate the delamination damage in the composite laminated beams.

APA, Harvard, Vancouver, ISO, and other styles

4

Mahboub, Radia. "Structural Conformational Study of Eugenol Derivatives Using Semiempirical Methods." Advances in Chemistry 2014 (October 20, 2014): 1–5. http://dx.doi.org/10.1155/2014/490358.

Full text

Abstract:

We investigated the conformational structure of eugenol and eugenyl acetate under torsional angle effect by performing semiempirical calculations using AM1 and PM3 methods. From these calculations, we have evaluated the strain energy of conformational interconversion. To provide a better estimate of stable conformations, we have plotted the strain energy versus dihedral angle. So, we have determined five geometries of eugenol (three energy minima and two transition states) and three geometries of eugenyl acetate (two energy minima and one transition state). From the molecular orbital calculations, we deduce that the optimized trans form by AM1 method is more reactive than under PM3 method. We can conclude that both methods are efficient. The AM1 method allows us to determine the reactivity and PM3 method to verify the stability.

APA, Harvard, Vancouver, ISO, and other styles

5

Dasgupta, A., C. Oyan, D. Barker, and M. Pecht. "Solder Creep-Fatigue Analysis by an Energy-Partitioning Approach." Journal of Electronic Packaging 114, no. 2 (June 1, 1992): 152–60. http://dx.doi.org/10.1115/1.2906412.

Full text

Abstract:

This study explores the possibility of using a unified theory of creep-fatigue, similar to the Halford-Manson strain-range partitioning method, for examining the effect of cyclic temperature range on fatigue life, over a wide range of temperatures. Other investigators have attempted similar techniques before for solder fatigue analysis. The present study is different since it proposes an energy-partitioning technique rather than strain-partitioning to examine the dependence of solder fatigue behavior on temperature dependent changes in the relative amounts of plastic and creep strains. The solder microstructure also dictates creep behavior but is assumed to be a given invariant parameter in this study. In other words, this study is targeted at as-cast microstructures and does not address post-recrystallization behavior. A sample solder joint of axisymmetric configuration, commonly found in leaded through-hole mounting technology, is analyzed with the help of nonlinear finite element methods. The strain history is determined for constant-amplitude temperature cycling with linear loading and unloading, and with constant dwells at upper and lower ends of the cycle. Large-deformation continuum formulations are utilized in conjunction with a viscoplastic constitutive model for the solder creep-plasticity behavior. Relevant material properties are obtained from experimental data in the literature. The results show significant amounts of rachetting and shakedown in the solder joint. Detailed stress-strain histories are presented, illustrating the strain amplitude, mean strain and residual stresses and strains. For illustrative purposes, the hysteresis cycles are partitioned into elastic, plastic and creep components. Such partitioned histories are essential in order to implement either the Halford-Manson strain-range partitioning technique or the energy-based approach suggested here, for analyzing the creep-fatigue damage accumulation in solder material. This study also illustrates the role and utility of the finite element method in generating the detailed stress-strain histories necessary for implementing the energy partitioning approach for creep-fatigue damage evaluation. Solder life prediction is presented as a function of cyclic temperature range at a given mean temperature.

APA, Harvard, Vancouver, ISO, and other styles

6

Walsh, Richard Michael, and R. Byron Pipes. "Strain energy release rate determination of stress intensity factors by finite element methods." Engineering Fracture Mechanics 22, no. 1 (January 1985): 17–33. http://dx.doi.org/10.1016/0013-7944(85)90156-0.

Full text

APA, Harvard, Vancouver, ISO, and other styles

7

Liu, Shuang, and Qing Wen Ren. "Elastic Energy Change Rate Method Research Using Energy Catastrophe Theory." Applied Mechanics and Materials 105-107 (September 2011): 374–80. http://dx.doi.org/10.4028/www.scientific.net/amm.105-107.374.

Full text

Abstract:

The state before and after structural failure is quite different, which leads to some sudden changes to its corresponding energy. According to energy catastrophe theory, each phenomenon that reflect system state mutations can regarded as the criterion of instability. Based on the energy catastrophe theory, the problem of concrete structure failure is dealt with various energy calculation methods. Moreover, the energy change rate method is put forward to search the omen point of structure deformation and failure. By comparing with structure total strain energy and plastic strain energy, it is shown that the elastic energy change rate can determine the omen point of structure failure more easily, directly and precisely. Finally, it is found that the stress-strain relationship of many materials in engineering are quite similar, which shows that using elastic energy change rate method to determine the omen point of structure failure has some certain universality in engineering.

APA, Harvard, Vancouver, ISO, and other styles

8

Norris, A. N., and D. L. Johnson. "Nonlinear Elasticity of Granular Media." Journal of Applied Mechanics 64, no. 1 (March 1, 1997): 39–49. http://dx.doi.org/10.1115/1.2787292.

Full text

Abstract:

The finite and incremental elasticity of a random packing of identical spheres is derived using energy methods. We consider different models for the contact forces between spheres, all of which are based upon or related to the fundamental Hertz theory; we consider only the special cases of perfect friction (no tangential slip) or no tangential friction. The existence of a strain energy function for the medium depends critically upon the type of contact. If the tangential contact stiffness is independent of the normal force, then the energy is well defined for all values of the macroscopic strain. Otherwise, the strain energy of the system is path dependent, in general. However, the concept of a quadratic strain energy function is always well defined for incremental motion superimposed on large confining stress and strain. For all models considered, we derive the changes in wave speeds due to incremental strains. For the models based upon an energy function we derive expressions for the third-order elastic constants as a function of confining pressure.

APA, Harvard, Vancouver, ISO, and other styles

9

Pilliadugula, Rekha, and N. Gopalakrishnan. "Crystallite size and micro-strain investigations of hydrothermally synthesized β-Ga2O3 by different analytical methods." Functional Materials Letters 13, no. 05 (July 2020): 2051018. http://dx.doi.org/10.1142/s1793604720510182.

Full text

Abstract:

XRD pattern of [Formula: see text]-Ga2O3 powder, synthesized through template-free two step hydrothermal method at low temperature thoroughly, is investigated by imposing different methods of analysis. Both crystallite sizes and micro-strains of the micro-structures are analyzed and compared. Along with the traditional Scherrer’s formula (S-average, LF and LFTZ), modified Williamson–Hall (W-H) method with UDM, USDM and UDEDM and Size-Strain Plot (SSP) method were used for the investigation. Stress and defect energy densities were calculated from USDM and UDEDM modified W-H plots of the powder sample, respectively. Detailed analysis of the crystallite size and micro-strain from different methods/models was done. Obtained crystallite sizes and micro-strains from different models were compared with the results obtained from TEM analysis. It was found that crystallite sizes obtained from UDM modified W-H analysis and SSP models well coincided with crystallite size observed from TEM micrograph.

APA, Harvard, Vancouver, ISO, and other styles

10

Guo, Ping, Jian Guo Lin, Bin Xia Cao, and Na Ta. "Isolation and Characterization of Petroleum Hydrocarbon Degrading Bacteria from the Bohai Sea, China." Advanced Materials Research 955-959 (June 2014): 728–31. http://dx.doi.org/10.4028/www.scientific.net/amr.955-959.728.

Full text

Abstract:

Fourteen petroleum hydrocarbon degrading bacteria strains were isolated from oil-contaminated site. Isolated strains were able use diesel oil as sole carbon and energy source. Bacterial strain HD1 was selected due to the luxuriant growth on oil agar. The oil degradation rate of strain HD1 was analyzed using UV-spectrometry-based methods. The result showed that the rate of diesel oil degradation of 75% was observed after 14days of cultivation.

APA, Harvard, Vancouver, ISO, and other styles

11

Kupchella, R., J. Kidney, and W. Hutchison. "Test Methods for Hyperelastic Characterization of Rubber4." Tire Science and Technology 37, no. 3 (September 1, 2009): 165–86. http://dx.doi.org/10.2346/1.3138763.

Full text

Abstract:

Abstract Optical methods using digital image correlation (DIC) are utilized in developing rubber constitutive tests. Two and three dimensional DIC systems are employed to measure strains on rubber specimens subjected to uniaxial, planar, and biaxial stress states. A special membrane inflation test was developed and is described for providing the biaxial constitutive data. Deformation-induced material property changes for the three modes of testing are quantified using a concept based on energy dissipation. The constitutive test strain ranges for each of the three modes are separately selected to equalize the material states. The methodology is applied to filled rubber compounds in order to characterize them in terms of hyperelastic behavior. Evaluation and comparison of several common hyperelastic models are given, and application to finite element modeling of a structural rubber specimen is described.

APA, Harvard, Vancouver, ISO, and other styles

12

Charalambus, B., K. Hartz, D. Blind, and E. Roos. "Methods for estimating strain in structures - conditions and definitions." Nuclear Engineering and Design 96, no. 2-3 (October 1986): 427–36. http://dx.doi.org/10.1016/0029-5493(86)90280-3.

Full text

APA, Harvard, Vancouver, ISO, and other styles

13

Augustin, M., and T. Balu. "Estimation of Lattice Stress and Strain in Zinc and Manganese Ferrite Nanoparticles by Williamson–Hall and Size-Strain Plot Methods." International Journal of Nanoscience 16, no. 03 (January 24, 2017): 1650035. http://dx.doi.org/10.1142/s0219581x16500356.

Full text

Abstract:

The Williamson–Hall (W–H) analysis and size-strain plot method (SSP) were used to study the lattice stress, strain and crystalline size of zinc (ZnFe2O4) and manganese (MnFe2O4) ferrite nanoparticles. These nanoparticles were synthesized by chemical co-precipitation method and characterized by powder X-ray diffraction analysis (PXRD). The PXRD results revealed that the sample product was crystalline with mixed type spinel with cubic structure. The crystalline development in the ZnFe2O4 and MnFe2O4 was investigated by X-ray peak broadening. The physical parameters such as strain, stress and energy density values were calculated more precisely for all the reflection peaks of PXRD using the W–H plots and SSP method. The variation in particle size, lattice strain, stress and energy density calculated from W–H analysis and SSP method reveals a nonuniform strain in the particles. This nonuniform strain was increased when the particle sizes were increased.

APA, Harvard, Vancouver, ISO, and other styles

14

Lin, Yongjun, Xianzhao Zhang, Wenqiang Xu, and Meng Zhou. "Importance Assessment of Structural Members Based on Elastic-Plastic Strain Energy." Advances in Materials Science and Engineering 2019 (June 9, 2019): 1–17. http://dx.doi.org/10.1155/2019/8019675.

Full text

Abstract:

Based on the elastic analysis, the existing methods of the importance assessment of structural members can only reflect the structural elastic behavior. To understand the plasticity and stiffness degradation of the structure, the present study proposes a member importance assessment method which takes the structural elastic-plastic strain energy or the generalized elastic-plastic strain energy as the performance parameter. First, the existing methods of member importance assessment are explained. Second, by pushover analysis, structural elastic-plastic strain energy is calculated in accordance with the story force-displacement curve, and structural generalized elastic-plastic strain energy is calculated according to the base shear-top displacement curve. Third, the importance of structural members is measured with its effect on the elastic-plastic strain energy or generalized elastic-plastic strain energy of the structure. Given the difference between structural performance parameters, the coefficient of member importance is defined. Finally, the importance of the masonry structure wall is quantitatively assessed using the elastic-plastic strain energy method, the generalized elastic-plastic strain energy method, the generalized stiffness method, and the ultimate bearing capacity method. Besides, the effect of the seismic fortification intensity and the number of structural stories on the wall importance assessment results is analyzed. According to the results, the elastic-plastic strain energy method and the generalized elastic-plastic strain energy method can both reveal the mechanical performance of elastic-plastic state of the structure under severe earthquake. Furthermore, the greater the seismic fortification intensity is, the more important the wall will be on the bottom floor, the more the total number of structural stories will be, and the more important the opening wall and its adjacent wall will be.

APA, Harvard, Vancouver, ISO, and other styles

15

HE, L., Y. W. LIU, W. J. TONG, J. G. LIN, and X. F. WANG. "SURFACE ENERGY ENGINEERING OF Cu SURFACE BY STRAIN: FIRST-PRINCIPLES CALCULATIONS." Surface Review and Letters 20, no. 06 (December 2013): 1350054. http://dx.doi.org/10.1142/s0218625x13500546.

Full text

Abstract:

Surface energies of strained Cu surfaces were studied systematically using first-principles methods. Results showed that the strain-stabilization of Cu surface was anisotropic and strongly related to the strain distribution. This strain-induced approach could be used as an effective way to engineer the surface energies of metals.

APA, Harvard, Vancouver, ISO, and other styles

16

KY, DANG VAN. "NEW METHODS IN FATIGUE OF STRUCTURES." International Journal of Computational Methods 11, no. 03 (June 2014): 1343005. http://dx.doi.org/10.1142/s0219876213430056.

Full text

Abstract:

Combining the application of the shakedown theory and a multiscale approach to analysis of fatigue allows interpreting all types of fatigue problems in an efficient manner. The description of the stabilized mechanical state after shakedown at the engineering macroscopic scale and at the mesoscopic scale of grains gives access to the engineering values which will drive the fatigue damage of the structure. The evolution of stress and strain tensors thus obtained for a cycle of fatigue allows predicting the fatigue strength of structures. At high cycle fatigue (HCF), when elastic shakedown takes place, the fatigue strength can be described by a simple combination of mesoscopic shear amplitude and hydrostatic tension at any point of the calculated structure, irrespective of the complexity of the structure and the loading. Two new developments incorporating spectral or modal approaches allow analyzing the fatigue resistance of structures undergoing vibrations in a very efficient manner. At low cycle fatigue (LCF), from the stabilized state of stress and strain, the fatigue strength is derived from a combination of the inelastic strain energy and the hydrostatic pressure. Numerous examples of fatigue analysis are presented.

APA, Harvard, Vancouver, ISO, and other styles

17

Miller, Lindsay M., N. C. Emley, P. Shafer, and Paul K. Wright. "Strain Enhancement within Cantilevered, Piezoelectric MEMS Energy Scavenging Devices." Advances in Science and Technology 54 (September 2008): 405–10. http://dx.doi.org/10.4028/www.scientific.net/ast.54.405.

Full text

Abstract:

We present the current status of cantilevered MEMS vibrational energy harvesting devices with sol-gel-derived lead zirconate titanate (PZT) as the active layer. Sol-gel-deposited PZT typically suffers from lower piezoelectric constants than those from other deposition methods, but it remains a simple method for depositing PZT films onto arbitrary wafer sizes and is a scalable process. Several different cantilever geometries are explored in order to improve power output by increasing the fraction of the material strained during deflection. Finite element analysis estimates of the mechanical strain within these cantilevers, when driven at resonance, demonstrate that choice of cantilever shape can significantly affect their power output.

APA, Harvard, Vancouver, ISO, and other styles

18

Leo, Donald J., Eric M. Austin, and Christopher Beattie. "Constrained Substructure Approach to Optimal Strain Energy Analysis." Journal of Vibration and Acoustics 123, no. 3 (December 1, 2000): 340–46. http://dx.doi.org/10.1115/1.1368117.

Full text

Abstract:

The chief tool for design of viscoelastic-based damping treatments over the past 20 years has been the modal strain energy (MSE) approach. This approach to damping design traditionally has involved a practitioner to vary placement and stiffness of add-on elements using experience and trial and error so as to maximize the add-on element share of system MSE in modes of interest. In this paper we develop a new technique for maximizing strain energy as a function of stiffness for add-on structural elements modeled as rank r perturbations to the original stiffness matrix. The technique is based on a constrained substructure approach allowing us to parameterize strain energy in terms of the eigenvalues of the perturbed structure. An optimality condition is derived that relates the input-output response at the attachment location of the add-on elements to the maximum achievable strain energy. A realizability condition is also derived which indicates whether or not the optimal solution is achievable with passive structural elements. This method has applications in the design of structural treatments for controlling sound and vibration and promises an efficient means of determining the limits of performance of passive structural treatments. An advantage of our approach over existing methods is that the maximum achievable strain energy fraction in the add-on elements is directly computable with the realizability condition then indicating whether the optimal solution is achievable.

APA, Harvard, Vancouver, ISO, and other styles

19

Audenino, A. L., E. M. Zanetti, and P. M. Calderale. "Assessment of Internal Damping in Uniaxially Stressed Metals: Exponential and Autoregressive Methods." Journal of Dynamic Systems, Measurement, and Control 120, no. 2 (June 1, 1998): 177–84. http://dx.doi.org/10.1115/1.2802407.

Full text

Abstract:

When a metallic material is highly stressed, its internal specific damping capacity increases showing a nonlinear behavior. In spite of this, the most part of experimental methods employ nonhomogeneous stress fields measuring only a volumetric average, often called structural damping. To overcome this problem the procedure herein presented extends the applicability of the plain traction or compression methods to higher frequency range (up to 300 Hz). The introduced methodology corrects for elastic energy and dissipated energy relative to the test machine and to the fixtures. The experimental procedure is based on the acquisition of a decay signal when the test machine excitation force has been removed. Two different methods to extract the pattern of internal damping versus material strain have been compared: one is based on least square exponential fitting while the other employs an autoregressive model. Best results have been obtained combining the two techniques taking into account also the variation of Young’s modulus with strain. The resulting curves of the loss factor as a function of strain amplitude for three steels and two cast irons are presented.

APA, Harvard, Vancouver, ISO, and other styles

20

Ren, Jiali, Yang Wang, De-Hua Han, Luanxiao Zhao, Teng Long, and Shuhang Tang. "Determining crack initiation stress in unconventional shales based on strain energy evolution." Journal of Geophysics and Engineering 18, no. 5 (September 3, 2021): 642–52. http://dx.doi.org/10.1093/jge/gxab041.

Full text

Abstract:

Abstract Determining the crack initiation stress (Ci) for unconventional shale rocks is of critical importance in describing the entire failure process of unconventional shale reservoirs. We propose a new method to identify Ci values based on triaxial failure tests on four organic shale samples, attempting to improve the shortcomings of other methods. The new method is based on the relationship between crack development and strain energy evolution (SEE). Additionally, the proposed SEE method is compared with three widely used methods, including crack volumetric strain (CVS), moving point regression (MPR) and the lateral strain response (LSR), intending to examine the performance of different methods. The contrastive results indicate that the LSR method cannot determine Ci when the rock ruptures without volumetric dilatancy, which frequently occurs in the compression process of organic shales. Ci values obtained using the SEE method are consistent with those from the CVS and MPR methods. However, the proposed SEE method with a solid physical basis is more objective and stable than the CVS and MPR methods. The proposed method, from one aspect, compensates for the shortcomings of other methods when facing different failure modes in organic shales. From the other aspect, it provides a way to precisely determine Ci values for applications in wellbore stability evaluation and hydraulic fracturing design.

APA, Harvard, Vancouver, ISO, and other styles

21

Thomas, Siby, K. M. Ajith, Sang Uck Lee, and M. C. Valsakumar. "Assessment of the mechanical properties of monolayer graphene using the energy and strain-fluctuation methods." RSC Advances 8, no. 48 (2018): 27283–92. http://dx.doi.org/10.1039/c8ra02967a.

Full text

APA, Harvard, Vancouver, ISO, and other styles

22

Fernández, Israel. "Combined activation strain model and energy decomposition analysis methods: a new way to understand pericyclic reactions." Phys. Chem. Chem. Phys. 16, no. 17 (2014): 7662–71. http://dx.doi.org/10.1039/c4cp00346b.

Full text

APA, Harvard, Vancouver, ISO, and other styles

23

Chen, Gui Qing, Gao Sheng Fu, Hong Ling Chen, Wen Duan Yan, Chao Zeng Cheng, and Ze Chang Zou. "Research on Hot Deformation Behavior of 3003 Al Alloy Prepared by Different Melt-Treatment Methods." Applied Mechanics and Materials 66-68 (July 2011): 1611–16. http://dx.doi.org/10.4028/www.scientific.net/amm.66-68.1611.

Full text

Abstract:

3003 Al alloy with different metallurgical quality were obtained by different melt-treatment methods, which were deformed by isothermal compression in the range of deformation temperature 300-500°C at strain rate 0.0l-10.0 s-1 with Gleeble-1500 thermal simulator. The results show that the material is sensitive to positive strain rate. The hot deformation activation energy (Q) bears linear relationship with inclusion content (H) of 3003 Al alloy prepared by different melt-treatment, Q=35.62 H+171.58, the activation energy of 3003 Al alloy prepared by high melt-treatment is the lowest (174.62 KJ×mol-1), which is beneficial to the material hot plastic deformation. The critical strain of 3003 Al alloy prepared by different melt-treatment methods is investigated through the work hardening rate. Finally, the critical conditions of the investigated alloy were determined to predict the dynamic recrystallization occurrence in the paper.

APA, Harvard, Vancouver, ISO, and other styles

24

Koruk, Hasan, and Kenan Y. Sanliturk. "Optimisation of damping treatments based on big bang–big crunch and modal strain energy methods." Journal of Sound and Vibration 333, no. 5 (February 2014): 1319–30. http://dx.doi.org/10.1016/j.jsv.2013.10.023.

Full text

APA, Harvard, Vancouver, ISO, and other styles

25

Sellers, Benjamin D., Natalie C. James, and Alberto Gobbi. "A Comparison of Quantum and Molecular Mechanical Methods to Estimate Strain Energy in Druglike Fragments." Journal of Chemical Information and Modeling 57, no. 6 (May 17, 2017): 1265–75. http://dx.doi.org/10.1021/acs.jcim.6b00614.

Full text

APA, Harvard, Vancouver, ISO, and other styles

26

Ye, Jia-Yu, Lu-Wen Zhang, and J. N. Reddy. "Large strained fracture of nearly incompressible hyperelastic materials: Enhanced assumed strain methods and energy decomposition." Journal of the Mechanics and Physics of Solids 139 (June 2020): 103939. http://dx.doi.org/10.1016/j.jmps.2020.103939.

Full text

APA, Harvard, Vancouver, ISO, and other styles

27

Curà, Francesca, Andrea Mura, and Fabrizio Scarpa. "Modal strain energy based methods for the analysis of complex patterned free layer damped plates." Journal of Vibration and Control 18, no. 9 (September 29, 2011): 1291–302. http://dx.doi.org/10.1177/1077546311417277.

Full text

Abstract:

The aim of this work is to study the modal behavior of structures covered with a complex pattern of viscoelastic material in Free Layer Damping (FLD) configuration in terms of damping performances. Two original methods based on the Modal Strain Energy (MSE) method named New Modified MSE method and the Corrected MSE method have been developed and applied to some test cases. A comparison between the new methods and the classic one has been done. Different viscoelastic distributions have been analyzed in order to evaluate how the patch design may influence the damping performances of the coupled structure. The structure has been discretized by means of a hybrid Finite Element (FE) developed to simulate the structure with the FLD viscoelastic treatment. The hybrid FE element has been benchmarked against an analytical example with full FLD coverage.

APA, Harvard, Vancouver, ISO, and other styles

28

Hu, Huiwen, Chengbo Wu, and Wei-Jun Lu. "Damage detection of circular hollow cylinder using modal strain energy and scanning damage index methods." Computers & Structures 89, no. 1-2 (January 2011): 149–60. http://dx.doi.org/10.1016/j.compstruc.2010.08.011.

Full text

APA, Harvard, Vancouver, ISO, and other styles

29

Kim, Duck Hoi, Soon Il Moon, and Jae Hoon Kim. "Determination of Dynamic Fracture Toughness Using Strain Measurement." Key Engineering Materials 261-263 (April 2004): 313–18. http://dx.doi.org/10.4028/www.scientific.net/kem.261-263.313.

Full text

Abstract:

By contrast with static fracture toughness determination, the methodology for dynamic fracture toughness characterization is not yet standardized and appropriate approaches must be devised. The accurate determination of the dynamic stress intensity factors must take into account inertial effects. Most methods for dynamic fracture toughness measurement are experimentally complex. However, dynamic fracture toughness determination using strain measurement is extremely attractive in terms of experimental simplicity. In this study, dynamic fracture toughness tests using strain measurement are performed. High rate tension and charpy impact tests are carried out for titanium alloy, maraging steel and Al alloys. In the case of evaluating the dynamic fracture toughness using high rate tension and charpy impact tests, load or energy methods are used commonly. The consideration about inertial effects is essential, because load or energy methods are influenced by inertia. In contrast, if the position for optimum response of strain is provided, dynamic fracture toughness evaluation using strain near crack tip is more accurate. To obtain the position for optimum response of strain, a number of gages were attached at angles of 60°. Reliability for experimental results is evaluated by Weibull analysis. The method presented in this paper is easy to implement in a laboratory and it provides accurate results compared to results from load or energy methods influenced by inertia.

APA, Harvard, Vancouver, ISO, and other styles

30

Alwar, R. S., and Suresh Babu. "INELASTIC STRAIN CONCENTRATION IN DIRECTIONALLY SOLIDIFIED MATERIALS." Transactions of the Canadian Society for Mechanical Engineering 19, no. 3 (September 1995): 331–46. http://dx.doi.org/10.1139/tcsme-1995-0018.

Full text

Abstract:

The application of Directionally Solidified (DS) materials in the construction of hot section parts (blades, vanes) of a gas turbine results in improvement in the engine performance and durability. Inelastic strain, an important parameter in low cycle fatigue (LCF) life prediction methodology, may be evaluated using simplified methods like Neuber’s rule and Equivalent Strain Energy Density Hypothesis. The objectives of the present investigation are to examine the validity of these methods in case of DS materials and to demonstrate using numerical methods that the low cycle fatigue life of DS materials is superior to isotropic materials.

APA, Harvard, Vancouver, ISO, and other styles

31

Song, Mou Sheng, and Mao Wu Ran. "Plastic Strain Energy in Low-Cycle Fatigue of A356 (Al-7Si-0.4Mg) Aluminum Alloys." Advanced Materials Research 194-196 (February 2011): 1210–16. http://dx.doi.org/10.4028/www.scientific.net/amr.194-196.1210.

Full text

Abstract:

In this paper, the problem of plastic strain energy density as a evaluation of low-cycle fatigue (LCF) properties for A356 alloys with various Ti content and Ti-addition methods is considered. The experimental results reveal that it is not the Ti-addition methods but the Ti content that has played an important role in influencing on the plastic strain energy density, thus on the LCF life. Whether for the electrolytic A356 alloys or for the melted A356 alloys, the alloys with 0.1% Ti content can consume higher cyclic plastic strain energy during the cyclic deformation compared with the alloys with 0.14% Ti content due to the better plasticity, giving rise to a better fatigue resistance and a longer LCF life. Because of the different macro or micro deformation mechanism, the fracture surface of electrolytic A356 alloy exhibits the diverse microstructural morphologies under the various strain amplitude.

APA, Harvard, Vancouver, ISO, and other styles

32

Vinjamuri, Krishna Bharath, Sashank Viswanadha, Hymavathi Basireddy, and Rajesh Kumar Borra. "X-Ray Diffraction Analysis by Williamson-Hall, Size-Strain, Halder-Wagner Plot Methods for Ni Doped CdS Nanoparticles." Applied Mechanics and Materials 903 (April 2021): 27–32. http://dx.doi.org/10.4028/www.scientific.net/amm.903.27.

Full text

Abstract:

Cadmium sulfide (CdS) doped with different concentrations of Ni (2, 4, 6, 8, and 10 %) nanoparticles have been synthesized by chemical co-precipitation method. X-ray diffraction (XRD) studies confirm the crystalline nature of Ni doped CdS nanoparticles had a hexagonal wurtzite structure. Williamson-Hall (W–H), Size-Strain Plot (SSP), and Halder-Wagner (H–W) methods have been used to investigate the average particle size, lattice strain, stress, and energy density from the XRD peak broadening analysis. In W–H method, the models of uniform deformation, uniform deformation stress, and uniform deformation energy density have been implemented to determine the elastic parameters.

APA, Harvard, Vancouver, ISO, and other styles

33

Fu, Rui-Min, Wei Tang, Hong Zhang, Ting-Ting Xue, and Wu-Ling Chen. "Screening of a Mannosylerythritol Lipids Producing Strain and Analysis on Its Products." Journal of Biobased Materials and Bioenergy 15, no. 3 (June 1, 2021): 408–12. http://dx.doi.org/10.1166/jbmb.2021.2065.

Full text

Abstract:

The purpose of this study is to improve the environmental pollution problem, the strains which can produce glycolipid biosurfactant and degrade petroleum hydrocarbons efficiently were screened out in this study. Six strains of glycolipid-producing fungi were isolated from the surface of apple skin by the methods of blood plate and oil plate. After comparing the oil drainage ability of each strain and using PCR to amplify the key genes for the synthesis of glycolipid surfactants, we screened a fungus K6 with emtl sequence. The strain was identified by morphological, physiological and biochemical tests and molecular phylogenetic analysis (5.8S, ITS1, ITS2). Its metabolites were analyzed by TLC and HPLC. The strain was identified as Pseudozyma churashimaensis, which could produce mannose and erythritol. The experiment of petroleum hydrocarbon degradation shows that strain K6 has strong emulsifying ability and the ability of degrading petroleum hydrocarbon. Strain K6, with the strong ability in producing biosurfactants and degrading petroleum, will have broad application prospects for bioremediation of petroleum contaminated environment.

APA, Harvard, Vancouver, ISO, and other styles

34

Young, Sung-Young, and Tae Hyun Nam. "Calculation of the elastic strain energy of inclusions by the Green's function and finite element methods." Materials Research Bulletin 47, no. 10 (October 2012): 2936–38. http://dx.doi.org/10.1016/j.materresbull.2012.04.052.

Full text

APA, Harvard, Vancouver, ISO, and other styles

35

Fajdiga, G., Z. Ren, and J. Kramar. "Comparison of virtual crack extension and strain energy density methods applied to contact surface crack growth." Engineering Fracture Mechanics 74, no. 17 (November 2007): 2721–34. http://dx.doi.org/10.1016/j.engfracmech.2007.01.016.

Full text

APA, Harvard, Vancouver, ISO, and other styles

36

Lian, Haojie, and Pengfei Wu. "The shape optimization of underground caverns based on strain energy criterion via explicit interface tracking methods." International Journal of Advances in Engineering Sciences and Applied Mathematics 12, no. 3-4 (December 2020): 183–92. http://dx.doi.org/10.1007/s12572-020-00281-7.

Full text

APA, Harvard, Vancouver, ISO, and other styles

37

Cui, Jianxia, Mark Rapo, Kiran Mathews, Charles Webber, and Laurel Ng. "Biomechanically Based Correlate for Localized Lung Contusion From Nonlethal Blunt Impact Projectiles." Military Medicine 186, Supplement_1 (January 1, 2021): 331–38. http://dx.doi.org/10.1093/milmed/usaa353.

Full text

Abstract:

ABSTRACT Introduction Injury mechanics of blunt impact projectiles differ from those experienced in whole body motor vehicle collisions because the effects are localized around the point of impact, and thus, injury thresholds based upon gross chest kinematics (e.g., force, velocity) may not be applicable across impact types. Therefore, knowledge of biomechanically based tissue injury correlates for blunt impact projectiles are needed to better guide design and development of protective systems as well as assess injury risks from blunt impact projectile weapons. Materials and Methods In this study, subject-specific swine finite element models were used to quantify the tissue-level stresses and strains resulting from high speed projectile impact. These tissue-level injury doses were correlated to pathology injury outcomes to produce injury risk curves for lung contusion. Details of the pathology data and finite element results are provided in Appendix 1. Survival analysis regression methods were applied to develop lung injury regression curves and a number of statistical methods were used to evaluate several biomechanical metrics as correlates to lung contusion. Uncertainty and sensitivity analyses were used to further confirm the selection of the correlate. Results Statistical analysis revealed that normalized strain-energy density was the best correlate for prediction of lung tissue damage. Going further, normalized strain-energy density also proved to be suitable for prediction of the percentage of contused lung volume, a more meaningful medical diagnosis. As expected, peak strain-energy density is most sensitive to muscle-skin properties, as quantified through a comprehensive uncertainty and sensitivity analysis over three sets of projectile weights and speeds. Conclusions Normalized strain-energy density was found to be the best correlate for prediction of lung tissue damage and correlate well to extent of contused lung volume.

APA, Harvard, Vancouver, ISO, and other styles

38

Li, Yingchao, Min Zhang, and Wenlong Yang. "Numerical and experimental investigation of modal-energy-based damage localization for offshore wind turbine structures." Advances in Structural Engineering 21, no. 10 (January 4, 2018): 1510–25. http://dx.doi.org/10.1177/1369433217750725.

Full text

Abstract:

Offshore wind turbine structures are prone to deterioration and damage during their service life in harsh marine environment. To explore highly efficient and robust damage detection methods for offshore wind turbine structures, three well-known modal strain energy indices are reviewed first and then a new index named total modal energy method is proposed. The innovation of the new index is the simultaneous use of modal strain energy and modal kinetic energy. To investigate the feasibility and robustness of the four modal-energy-based methods, numerical and experimental studies are conducted on a tripod-type offshore wind turbine structure with simulated and measured data. It is indicated that all the four modal-energy-based methods work well with limited incomplete modal data, especially for the single-damage cases. While for the cases of multiple damage locations, the new total modal energy index significantly outperforms the traditional modal strain energy indices. Moreover, high robustness is shown for the indices, when the measured mode shapes of undamaged and damaged structures are polluted with the same noise level. However, when their noise levels have some difference, two of the modal strain energy indices turn invalid, but the new total modal energy index still shows stronger robustness. As frequencies are also used in the total modal energy index, its robustness to the noise in modal frequencies is also studied. It is shown that the results are slightly affected by the measurement noise in modal frequencies. Besides, the influence of finite element modeling errors is also investigated with both simulated and experimental data. Results show that all the four modal-energy-based methods are all very stable and insensitive to certain modeling errors. So, finite element model updating is not necessary in the test structure herein.

APA, Harvard, Vancouver, ISO, and other styles

39

Seshadri, R., and R. K. Kizhatil. "Robust Approximate Methods for Estimating Inelastic Fracture Parameters." Journal of Pressure Vessel Technology 117, no. 2 (May 1, 1995): 115–23. http://dx.doi.org/10.1115/1.2842098.

Full text

Abstract:

Robust approximate methods to estimate the inelastic energy release rate J, and the creep crack-growth parameter, C*, for cracked components are described in this paper. These methods use linear elastic finite element analysis in conjunction with the concepts of the generalized local stress strain (GLOSS) analysis and redistribution nodes (r-nodes), and are readily applicable to complex geometries and loadings. J-estimates obtained by the use of robust methods are found to be in good agreement with the results of elastic-plastic finite element analysis.

APA, Harvard, Vancouver, ISO, and other styles

40

Wilcox, Dan, Peter Loveridge, Saurabh Kabra, Tung Lik Lee, Jeremy Moor, and David Jenkins. "Measurement of residual strain in tantalum-clad tungsten after hot isostatic pressing." Journal of Neutron Research 22, no. 2-3 (October 20, 2020): 287–97. http://dx.doi.org/10.3233/jnr-200181.

Full text

Abstract:

Tantalum-clad tungsten targets are a popular choice for spallation neutron production, due to the combination of high neutron yield and corrosion resistance. Such targets typically use the Hot Isostatic Press (HIP) process to bond the cladding to the core; this produces a strong bond but also introduces large residual stresses in the target and cladding. This is of particular interest at the ISIS neutron source, because cladding breaches are currently believed to limit the lifetime of ISIS TS2 targets. Two different and complementary methods were used to measure the residual strain in a tantalum-clad tungsten strip manufactured using the same HIP process as ISIS targets. The strip was produced with deliberately asymmetric cladding, causing it to deflect in proportion to the residual stress. FEA simulations were used to back-calculate the stress from the measured deflection. The strip was then placed on the ISIS instrument ENGIN-X, which allowed detailed through-thickness strain profiles to be measured via neutron diffraction. The results of both methods confirm the presence of large residual strains, and agree reasonably well with FEA simulations of the cladding process.

APA, Harvard, Vancouver, ISO, and other styles

41

Irfan, H., K. Mohamed Racik, and S. Anand. "X-ray peak profile analysis of CoAl2O4 nanoparticles by Williamson-Hall and size-strain plot methods." Modern Electronic Materials 4, no. 1 (May 1, 2018): 31–40. http://dx.doi.org/10.3897/j.moem.4.1.33272.

Full text

Abstract:

CoAl2O4nanoparticles were prepared by a sol-gel process using citric acid as chelating agent with different calcination temperatures of 600 to 900 °C. The crystalline spinel cubic phase was confirmed by X-ray diffraction results. High-resolution scanning electron microscopy (HRSEM) revealed that nanoparticles of CoAl2O4morphology showed spherical forms with a certain degree of agglomeration. The Williamson-Hall (W-H) method and size-strain method to evaluate the size of crystallites and strain in the CoAl2O4nanoparticles peak broadening were applied. Physical parameters such as strain and stress values were calculated for all XRD reflection peaks corresponding to the cubic spinel phase of CoAl2O4in the range of 20 to 70° from the modified plot shape by W-H plot assuming a uniform deformation model (UDM), uniform stress deformation model (USDM), uniform deformation energy density model (UDEDM) and by the size-strain plot method (SSP). The CoAl2O4NPs crystal size calculated on the W-H plots and the SSP method are in good agreement with the HRSEM Scherrer method.

APA, Harvard, Vancouver, ISO, and other styles

42

Cai, Xuesong, Shijun Sun, and Guangchun Zhou. "An Experimental Strain-Based Study on the Working State of Husk Mortar Wallboards with Openings." Applied Sciences 10, no. 2 (January 19, 2020): 710. http://dx.doi.org/10.3390/app10020710.

Full text

Abstract:

Rice husks as common agricultural remnants with low density and good thermal conductivity properties have been used in infill walls in the northern area of China. Accordingly, many tests and numerical simulations were conducted to address a difficult issue, the inaccurate estimation on the lateral load-bearing capacity of different types of husk mortar energy-saving (HMES) wallboards. The difficulty has not been overcome so far, implying that the novel methods are anticipated to achieve the accurate estimation. This paper tests the full-scale HMES wallboards with different openings and obtains the strains at the points distributed on the wallboard sides. The experimental strains are modeled as the approximate strain energy values to produce the characteristic parameter of the HMES wallboard’s stressing state. Furthermore, the inherent working state characteristic points of HMES wallboards are revealed from the evolution of the characteristic parameter called as the normalized approximate strain energy sum, leading to the redefinition of the failure loads for the HMES wallboards. Finally, it investigates the stressing state mode evolution of the HMES wallboard around the failure loads. The achieved results provide the reference to the accurate estimation of the bearing capacity of the HMES wallboards.

APA, Harvard, Vancouver, ISO, and other styles

43

Molladavoodi, H., and Y. RahimiRezaei. "Heterogeneous Rock Simulation Using DIP-Micromechanics-Statistical Methods." Advances in Civil Engineering 2018 (2018): 1–10. http://dx.doi.org/10.1155/2018/7010817.

Full text

Abstract:

Rock as a natural material is heterogeneous. Rock material consists of minerals, crystals, cement, grains, and microcracks. Each component of rock has a different mechanical behavior under applied loading condition. Therefore, rock component distribution has an important effect on rock mechanical behavior, especially in the postpeak region. In this paper, the rock sample was studied by digital image processing (DIP), micromechanics, and statistical methods. Using image processing, volume fractions of the rock minerals composing the rock sample were evaluated precisely. The mechanical properties of the rock matrix were determined based on upscaling micromechanics. In order to consider the rock heterogeneities effect on mechanical behavior, the heterogeneity index was calculated in a framework of statistical method. A Weibull distribution function was fitted to the Young modulus distribution of minerals. Finally, statistical and Mohr–Coulomb strain-softening models were used simultaneously as a constitutive model in DEM code. The acoustic emission, strain energy release, and the effect of rock heterogeneities on the postpeak behavior process were investigated. The numerical results are in good agreement with experimental data.

APA, Harvard, Vancouver, ISO, and other styles

44

Duffey, T. A., S. W. Doebling, C. R. Farrar, W. E. Baker, and W. H. Rhee. "Vibration-Based Damage Identification in Structures Exhibiting Axial and Torsional Response." Journal of Vibration and Acoustics 123, no. 1 (April 1, 2000): 84–91. http://dx.doi.org/10.1115/1.1320445.

Full text

Abstract:

A method is derived to detect and localize linear damage in a structure using the measured modal vibration parameters. This method is applicable when the vibration strain energy is stored in the axial or torsional modes, which differentiates it from previously derived strain-energy-based methods. The new method is compared to the previously derived flexibility-change method for comparison. Both methods are verified by application to an analytical eight degree of freedom model. Experimental validation for both methods is also presented by application to an experimental eight degree of freedom spring-mass structure.

APA, Harvard, Vancouver, ISO, and other styles

45

Zhao, Jin Fang, and Qun Zhao. "Typical Calculation Method of Stress Intensity Factors and Crack Growth Criterions on Infinite Plate Containing Hole-Edge Cracks." Advanced Materials Research 568 (September 2012): 154–58. http://dx.doi.org/10.4028/www.scientific.net/amr.568.154.

Full text

Abstract:

This paper introduces a finite element analysis software FRANC2D/L to calculate the stress intensity factor (SIF) and simulate the crack growth. Samples with infinite plate containing center crack, one hole-edge crack and two symmetrical hole-edge cracks were analyzed by this software. Comparing the SIF calculation results of the three samples based on displacement correlation method, J-integral method and virtual crack closure integral method, the results show that the three methods are all suitable for calculating the SIF problems, and the calculation precision of J-integral method and virtual crack closure integral method are better. Comparing the three crack growth criterion of maximum circumferential stress, maximum strain energy release rate and minimum strain energy density, the calculation velocity and precision of maximum circumferential stress criterion and minimum strain energy density criterion are prior to maximum strain energy release rate criterion. The calculating time and angle error of maximum strain energy release rate criterion is larger than that of the other two criterions．

APA, Harvard, Vancouver, ISO, and other styles

46

Meng, Hai Ping, and Xin Yan Lin. "Damage Orientation Method Based on the Modal Kinetic Energy." Applied Mechanics and Materials 256-259 (December 2012): 1112–16. http://dx.doi.org/10.4028/www.scientific.net/amm.256-259.1112.

Full text

Abstract:

Dynamic methods by structural vibration responses and system dynamic characteristic parameters are the main methods for structural damage identification. Based on the modal strain energy method and used unit location matrix instead of element mass matrix, modal kinetic method is proposed. Two kinds of typical damage condition were simulated and the results show that the method can reduce structural finite element model accuracy, calculate simply and realize the initial damage location.

APA, Harvard, Vancouver, ISO, and other styles

47

Tang, Xiaoning, Deshan Cheng, Jianhua Ran, Daiqi Li, Chengen He, Shuguang Bi, Guangming Cai, and Xin Wang. "Recent advances on the fabrication methods of nanocomposite yarn-based strain sensor." Nanotechnology Reviews 10, no. 1 (January 1, 2021): 221–36. http://dx.doi.org/10.1515/ntrev-2021-0021.

Full text

Abstract:

Abstract Yarn-based strain sensor is an emerging candidate for the fabrication of wearable electronic devices. The intrinsic properties of yarn, such as excellent lightweight, flexibility, stitchability, and especially its highly stretchable performance, stand out the yarn-based strain sensor from conventional rigid sensors in detection of human body motions. Recent advances in conductive materials and fabrication methods of yarn-based strain sensors are well reviewed and discussed in this work. Coating techniques including dip-coating, layer by layer assemble, and chemical deposition for deposition of conductive layer on elastic filament were first introduced, and fabrication technology to incorporate conductive components into elastic matrix via melt extrusion or wet spinning was reviewed afterwards. Especially, the recent advances of core–sheath/wrapping yarn strain sensor as-fabricated by traditional spinning technique were well summarized. Finally, promising perspectives and challenges together with key points in the development of yarn strain sensors were presented for future endeavor.

APA, Harvard, Vancouver, ISO, and other styles

48

Bechtel, G. S., and T. S. Cook. "Load Control–Strain Control Isochronous Stress–Strain Curves for High Temperature Nonlinear Analysis." Journal of Engineering for Gas Turbines and Power 117, no. 2 (April 1, 1995): 364–70. http://dx.doi.org/10.1115/1.2814103.

Full text

Abstract:

Aircraft gas turbine components are subjected to severe operating conditions. High temperatures, large thermal strains, and mechanical loads combine to cause the material to undergo significant nonlinear behavior. In order to assure safe, durable components, it is necessary that analysis methods be available to predict the nonlinear deformation. General purpose finite element codes are available to perform elastic and viscoplastic analyses, but the analyses are expensive. Both large plastic and creep strain analyses can require significant computer resources, but typically a plastic solution is more economical to run than a time-stepping creep or viscoplastic model solution. For those applications where the deformation is principally time dependent, it is advantageous to include time-dependent creep effects in a “constant time” or “isochronous” analysis. Although this approach has been used in the past to estimate rupture life, this paper will present several significant new techniques for doing an isochronous analysis to analyze time-dependent deformation.

APA, Harvard, Vancouver, ISO, and other styles

49

Zhao, Wei Mao, Wei Zheng Zhang, and Zhao Ju Qin. "Study on LCF Lifetime Prediction of Thermal Shock." Applied Mechanics and Materials 152-154 (January 2012): 924–30. http://dx.doi.org/10.4028/www.scientific.net/amm.152-154.924.

Full text

Abstract:

Gray cast iron specimen was heated to a fixed temperature with high frequency induction heating equipment, then was cooled to room temperature by spraying water to the heated surface. This process was repeated until a crack whose length exceeds 3mm appeared. Transient cyclic heat transfer and stress-strain FEA analysis was conducted to obtain specimen’s stress-strain state, then different LCF life prediction methods based on strain and energy were presented and contrasted, and results showed modified dissipated energy method with maximal hydrostatic pressure was more accurate than other methods. With the help of modified dissipated energy method, the relationship between thermal shock life, highest cooling temperature and cooling speed was studied, and the effect law of highest cooling temperature and cooling heat transfer coefficient on life was obtained.

APA, Harvard, Vancouver, ISO, and other styles

50

Kim, J., H. A. A. Tchelepi, and R. Juanes. "Stability, Accuracy, and Efficiency of Sequential Methods for Coupled Flow and Geomechanics." SPE Journal 16, no. 02 (January 17, 2011): 249–62. http://dx.doi.org/10.2118/119084-pa.

Full text

Abstract:

Summary We perform detailed stability and convergence analyses of sequential-implicit solution methods for coupled fluid flow and reservoir geomechanics. We analyze four different sequential-implicit solution strategies, where each subproblem (flow and mechanics) is solved implicitly: two schemes in which the mechanical problem is solved first—namely, the drained and undrained splits—and two schemes in which the flow problem is solved first—namely, the fixed-strain and fixed-stress splits. The von Neumann method is used to obtain the linear-stability criteria of the four sequential schemes, and numerical simulations are used to test the validity and sharpness of these criteria for representative problems. The analysis indicates that the drained and fixed-strain splits, which are commonly used, are conditionally stable and that the stability limits depend only on the strength of coupling between flow and mechanics and are independent of the timestep size. Therefore, the drained and fixed-strain schemes cannot be used when the coupling between flow and mechanics is strong. Moreover, numerical solutions obtained using the drained and fixed-strain sequential schemes suffer from oscillations, even when the stability limit is honored. For problems where the deformation may be plastic (nonlinear) in nature, the drained and fixed-strain sequential schemes become unstable when the system enters the plastic regime. On the other hand, the undrained and fixed-stress sequential schemes are unconditionally stable regardless of the coupling strength, and they do not suffer from oscillations. While both the undrained and fixed-stress schemes are unconditionally stable, for the cases investigated we found that the fixed-stress split converges more rapidly than the undrained split. On the basis of these findings, we strongly recommend the fixed-stress sequential-implicit method for modeling coupled flow and geomechanics in reservoirs.

APA, Harvard, Vancouver, ISO, and other styles

Journal articles on the topic 'Strain energy methods'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles