The Effect of Plate Curvature on the Influence of Macroscale Geometric Voids in Controlling Stress Wave Propagation

2020 ◽  
Author(s):  
C. S. Florio
Keyword(s):  
Wave Propagation ◽  
Stress Wave ◽  
Plane Stress ◽  
Cylindrical Shells ◽  
Reaction Force ◽  
Stress Waves ◽  
Stress Wave Propagation ◽  
Axial Impact ◽  
Plate Curvature ◽  
Metal Plates

Abstract Much work has been done to create and understand means to control the propagation of acoustic and light waves through materials and structures. The ability to perform similar studies on the control of stress waves has implications not only for the development of capabilities to disrupt stress waves in order to limit their damage, but also to direct stress waves in order to tailor the behavior of a structure for a specific functional goal. Recent studies have demonstrated the use of voids and inclusions of varying size, geometry, arrangement, and composition in structures to attenuate impact forces or cloak stress waves in thin, flat, plane stress plates. However, many structures that may benefit from these wave modification methods are comprised of cylindrical shells. It is not currently known how well the techniques to control wave propagation and trends identified in plane stress plates can be applied to structures with cylindrical shells. Therefore, this study develops and uses computational modeling methods to examine the modification and control of stress waves induced by an axial impact load in metal plates of varying curvature through the inclusion of macroscale voids. Methods are developed and used in this work to study the response of metal plates of varying curvature with and without voids of different shapes and arrangement to axial impact loads. The response is quantified through the magnitude of the fixed end reaction force and through normal oscillations of discrete points along the length of the plate. Fast Fourier transformation and wavelet coherence techniques are used to understand both the time-averaged and time-dependent oscillation behavior. Correlations are drawn between plate curvature and void design on the control of the propagation of stress waves. The knowledge gained can help guide the understanding design of these stress wave modification features.

scholarly journals A Numerical and Experimental Aproach of Stress Waves Propagation in Short Tronconical Bars Under Axial Impact

2018 ◽  
Vol 24 (3) ◽  
pp. 101-106
Author(s):  
Nicolae Iliescu ◽  
Vasile Nastasescu ◽  
Ghiță Barsan
Keyword(s):  
Wave Propagation ◽  
Numerical Analysis ◽  
Stress Wave ◽  
Cross Sections ◽  
Stress Waves ◽  
Stress Wave Propagation ◽  
Experimental Investigations ◽  
Axial Impact ◽  
Calculation Methodology ◽  
Waves Propagation

Abstract In the first part of the paper, using the numerical simulations with FEM and the results of some investigations made with different experimental techniques, a calculation methodology was developed for the study of the stress waves propagation in the short tronconical bars subjected at axial impact. Because a good agreement between data obtained from numerical analysis and experimental investigations was observed, the numerical model of calculus conceived for this study was considered validated. The calculus model established was used to investigate other aspects connected of stress wave propagation in the short tronconical bars. In the second part of the paper, using established calculus model and numerical analysis with Finite Element Method the influence of bar conicity on stress wave propagation and on stress distribution in different cross sections of the bar was analyzed

The Micro-Mechanism of Vibration Cutting Stress Wave and the Analysis of Macro-Processing Effect

2009 ◽  
Vol 407-408 ◽  
pp. 632-635
Author(s):  
Jia Yao ◽  
Wei Lu ◽  
Chun Shan Liu
Keyword(s):  
Finite Element Method ◽  
Stress Intensity Factor ◽  
Wave Propagation ◽  
Stress Wave ◽  
Dynamic Stress ◽  
Dynamic Stress Intensity Factor ◽  
Shear Angle ◽  
Stress Waves ◽  
Stress Wave Propagation ◽  
Vibration Cutting

The specification of the vibration cutting loading is a decision factor for the generation of stress wave and the stress wave propagation has a significant impact on its micro-mechanism. Making the stress waves’ generation in the cutting area of vibration cutting for entry point, the analysis of internal inflection wave, inflection fracture and dynamic stress intensity factor has been carried out, the simulation of vibration cutting has also been done by finite element method, the essential of energy concentrated role, shear angle increment and cutting quality improvement has been explained.

Stress Wave Propagation, Dynamic Material Response, and Quantitative Non-Destructive Evaluation

1985 ◽  
Vol 38 (10) ◽  
pp. 1276-1278 ◽  
Author(s):  
R. J. Clifton
Keyword(s):  
Wave Propagation ◽  
Dynamic Loading ◽  
Stress Wave ◽  
Stress Waves ◽  
Ultrasonic Waves ◽  
Material Behavior ◽  
Stress Wave Propagation ◽  
Reliable Determination ◽  
Wide Range

Stress wave propagation is of fundamental importance in modern technology because it provides the primary means for the nondestructive examination of defects and in-homogeneities in opaque materials and the only means for studying the response of materials under the dynamic loading conditions associated with impact and explosions. Advances in such diverse technologies as nuclear reactor safety, integrated circuit inspection, and armor penetration depend strongly on advances in the modeling of the propagation of stress waves and in the improved characterization of the dynamic response of materials. Stress waves play a central role in a wide range of geotechnical and geophysical applications including reservoir exploration, earthquake monitoring, and the prediction of ground motion due to earthquakes and blast loading. Because of the inherent complexity of stress waves in solids (i.e., three wave speeds, anisotropy, and inhomogeneity), as well as the importance of nonlinearity in applications involving intense loading, progress in the modeling of stress wave phenomena depends critically on large scale computations. Increased availability of supercomputers provides an excellent opportunity for advances in the modeling of three dimensional phenomena, including such complicating features as anisotropy, inhomogeneity, defects, nonlinearity, and sliding interfaces. Research is needed on accurate and efficient algorithms for these calculations and for acoustic imaging which requires algorithms for inverse problems in which the size and shape of defects, as well as variations in density and in elastic moduli, are to be obtained by probing the region of interest with ultrasonic waves. Improved characterization of the sources and receivers of ultrasound is essential for reliable determination of the required geometrical features and material properties. Improved understanding of the dynamic inelastic response of materials is crucial to realizing the full benefits of the emerging computational power. Strain rate sensitivity, shear strain localization, crack propagation, twinning, and phase transformations are all aspects of mechanical response that need to be modeled in many dynamic loading applications. Basic experiments on these aspects of material behavior combined with computer simulation of the experiments should lead to significant progress in understanding the underlying mechanisms and, thereby, to improved models for use in computations.

Plane Stress Wave Propagation in Solids

1970 ◽  
Vol 41 (1) ◽  
pp. 360-363 ◽  
Author(s):  
Richard Fowles ◽  
Roger F. Williams
Keyword(s):  
Wave Propagation ◽  
Stress Wave ◽  
Plane Stress ◽  
Stress Wave Propagation

scholarly journals A Numerical Simulation of Blasting Stress Wave Propagation in a Jointed Rock Mass under Initial Stresses

2021 ◽  
Vol 11 (17) ◽  
pp. 7873
Author(s):  
Qian Dong ◽  
Xinping Li ◽  
Yongsheng Jia ◽  
Jinshan Sun
Keyword(s):  
Wave Propagation ◽  
Rock Mass ◽  
Initial Stress ◽  
Stress Wave ◽  
Jointed Rock ◽  
Jointed Rock Mass ◽  
Stress Waves ◽  
Initial Stresses ◽  
Stress Wave Propagation ◽  
Rock Masses

The initial stresses have a strong effect on the mechanical behavior of underground rock masses, and the initial stressed rock masses are usually under strong dynamic disturbances such as blasting and earthquakes. The influence mechanism of a blasting excavation on underground rock masses can be revealed by studying the propagation of stress waves in them. In this paper, the improved Mohr-Coulomb elasto-plastic constitutive model of the intact rock considering the initial damage was first established and numerically implemented in Universal Distinct Element Code (UDEC) based on the variation of the experimental stress wave velocity in the initial stressed intact rock, and the feasibility of combining the established rock constitutive model and the BB (Bandis-Barton) model which characterizes the nonlinear deformation of the joints to simulate stress waves across jointed rock masses under initial stress was validated by comparing the numerical and model test results subsequently. Finally, further parameter studies were carried out through the UDEC to investigate the effect of the initial stress, angle, and number of joints on the transmission of the blasting stress wave in the jointed rock mass. The results showed that the initial stress significantly changed the propagation of the stress waves in the jointed rock mass. When the initial stress was small, the transmission coefficients of the stress waves in the jointed rock were vulnerable to be influenced by the variation of the angle and the number of joints, while the effect of the angle and the number of joints on the stress wave propagation gradually weakened as the initial stress increased.

Damage Severity Estimation of Timber Poles Using Stress Wave Propagation and Wavelet Entropy Evolution

2020 ◽  
Vol 4 (1) ◽  
Author(s):  
S. Bandara ◽  
P. Rajeev ◽  
E. Gad ◽  
B. Sriskantharajah
Keyword(s):  
Wave Propagation ◽  
Numerical Model ◽  
Stress Wave ◽  
Estimation Method ◽  
Stress Waves ◽  
Stress Wave Propagation ◽  
Discrete Wavelet ◽  
Wavelet Entropy ◽  
Time Frequency ◽  
Severity Estimation

Abstract Timber poles are widely used in electricity transmission and telecommunication sectors throughout the world. The stress wave propagation for the condition assessment of timber poles is identified as a promising non-destructive testing (NDT) technique due to its simplicity and cost-effectiveness compared to other traditional methods. In this paper, a novel damage severity evaluation criterion for timber poles is proposed on the basis of short-time wavelet entropy of the reflected stress waves. The stress waves are generated by transverse impacts close to the ground level of the pole. The reflected stress waves are recorded and processed in the time frequency domain using the discrete wavelet transform. The decomposed signal components using discrete wavelet analysis are used to determine the wavelet entropy. The wavelet entropies of intact and damaged poles are compared to obtain the relative wavelet entropy (RWE) for damage severity estimation. Further, a numerical model for an in situ pole system is developed to simulate the transverse stress wave propagation and to evaluate the capability of the proposed defect severity estimation method. The developed numerical model is validated with experimental data from controlled testing and the data from field tests. The validated numerical model is then used to simulate different defect scenarios. The wavelet entropy is sensitive to the damage severity in timber poles and can be used as an effective tool to evaluate the severity of damages.

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