An Analysis of Longitudinal Elastic-Plastic Pulse Propagation

1966 ◽  
Vol 33 (2) ◽  
pp. 248-255 ◽  
Author(s):  
R. J. Clifton ◽  
S. R. Bodner
Keyword(s):  
Pulse Propagation ◽  
Pure Aluminum ◽  
General Shape ◽  
Stress Strain ◽  
One Dimensional ◽  
Elastic Plastic ◽  
Strain Behavior ◽  
Commercially Pure ◽  
Strain Axis ◽  
The One

The one-dimensional, rate-independent theory of elastic-plastic wave propagation for smooth stress-strain curves concave toward the strain axis is applied to the problem of a long uniform bar loaded at one end by a pressure pulse of short duration. The essential features of the solution are obtained for the case of a semi-infinite bar and for the case of a finite bar whose other end is stress-free by using the method of characteristics in the t-x plane. The general shape of boundaries in the t-x plane which separate regions governed by the dynamic elastic equations from regions governed by the dynamic plastic equations is presented. The nature of the discontinuities that occur at these boundaries is also discussed. For the finite-bar case the analysis is given for materials which exhibit isotropic work hardening and for materials for which the stress-strain behavior in tension is independent of any previous compression. The main features of the solution are in agreement with the behavior observed for annealed, commercially pure aluminum bars subjected to explosive loading at one end. These experiments will be reported subsequently.

Response spectra of earthquakes on very soft clay

1964 ◽  
Vol 54 (3) ◽  
pp. 855-866
Author(s):  
J. I. Bustamante
Keyword(s):  
Mexico City ◽  
Soft Clay ◽  
Response Spectra ◽  
Wave Reflections ◽  
General Shape ◽  
Dimensional Theory ◽  
Multiple Wave ◽  
One Dimensional ◽  
Velocity Spectra ◽  
The One

Abstract The response spectra of two strong and two mild earthquakes recorded on the thick lacustrine formation of Mexico City in 1961 and 1962 are presented. The velocity spectra of the two strong ones are compared with studies made independently by Jennings. Discrepancies there-with are explained in terms of wave reflections. A criterion to simplify data reduction and spectrum computations is supported by these comparisons. Velocity and pseudovelocity spectra are practically alike. The period corresponding to the maximum peak and the general shape of these curves agree closely with those predicted applying the one-dimensional theory of multiple wave reflections to the formations in question.

scholarly journals On reflected and transmitted stress waves at an elastic-plastic boundary

1980 ◽  
Vol 15 (1) ◽  
pp. 15-20 ◽  
Author(s):  
A S Khan
Keyword(s):  
Wave Theory ◽  
Finite Amplitude ◽  
Stress Waves ◽  
Constitutive Relationship ◽  
One Dimensional ◽  
Elastic Plastic ◽  
Linear Elastic ◽  
Transmitted Waves ◽  
The One ◽  
Dynamic Plastic Deformation

A theoretical analysis for the reflected and transmitted waves at an elastic-plastic boundary is presented. The basis of this analysis is the linear elastic wave theory in a hard load-bar and the one-dimensional, strain-rate-independent theory of finite-amplitude plastic waves in a soft specimen. The constitutive relationship during dynamic plastic deformation is an experimentally determined dynamic response function in the soft material. The analysis predicts results that agree very closely with experimental results.

Unified Approach for Notch Stress Strain Conversion (NSSC) Rules

2012 ◽  
Author(s):  
R. Adibi-Asl ◽  
R. Seshadri
Keyword(s):  
Interpolation Method ◽  
Notch Root ◽  
Three Dimensional ◽  
Linear Interpolation ◽  
Unified Approach ◽  
Stress Strain ◽  
Elastic Plastic ◽  
Strain Behavior ◽  
Notch Stress ◽  
Non Linear

There are several simplified methods, known as notch stress-strain conversion (NSSC) rules that provide an approximate formula to relate local elastic-plastic stresses and strains at the notch root to those estimated elastically. This paper investigates a unified approach that estimates non-linear and history dependent stress-strain behavior of the notches using the conventional NSSC rules. A non-linear interpolation method is adapted to estimate the elastic-plastic stress and strain at notches. A comparison is made between the finite element results for several notch configurations (with and without three dimensional effects) and those obtained from NSSC rules and the proposed formulation.

Integrating Friction-Stir Back Extrusion to Powder Metallurgy

2021 ◽  
Author(s):  
Sahil Dhoka ◽  
Scott W. Wagner ◽  
Himansshu Abhi ◽  
Nicholas V. Hendrickson ◽  
William J. Emblom
Keyword(s):  
Pure Aluminum ◽  
Metal Powders ◽  
X Ray Diffraction ◽  
Friction Stir ◽  
Fine Grained ◽  
Commercially Pure ◽  
Automobile Components ◽  
The One ◽  
Processing Techniques ◽  
Improved Methods

Abstract Reducing fuel consumption has been a driving factor for researchers and manufacturers to continually develop improved methods for reducing the weight of automobiles or lightweighting. These vehicle lightweighting demands have directed researchers to look to using materials that are typically more difficult to manufacture in their studies. As a result, friction stir processing techniques are being looked at more closely. There are advantages to using friction stir methods. Dissimilar metals can be welded and fine-grained products can be created using friction stir methods to name a few. It can be an ideal solution for manufacturing high-conductive metals and alloys. Foamed aluminum tube similar to the one shown by Yoshiko Hangai et al [1] can be formed using the proposed process which could be used to develop lightweight automobile components. This paper provides preliminary results and insights gained when fine metal powders were used in a friction stir back extrusion (FSBE) setup. The tooling consisted of a D2 tool steel die with an H13 rotating probe mounted in a CNC mill. Within the die, commercially pure aluminum powder was topped by an aluminum cap with a milled pocket in the center. This pocket was used to locate the spin tool in the center of the cap and reduce the potential for the tool to drift and deflect. The cap was also used for compacting the powdered aluminum. X-ray diffraction indicated that Al13Fe4 was formed, indicating that the temperature within the die reached a minimum of 800°C and also indicated that the powder had the potential to partially sinter and melt.

Thermal Elastic-Plastic Analysis Considering Temperature Rise by Rapid Plastic Deformation in Undermatched Joints

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
Masahito Mochizuki ◽  
Gyu-Baek An ◽  
Masao Toyoda
Keyword(s):  
Plastic Deformation ◽  
Strain Rate ◽  
Temperature Rise ◽  
Structural Steels ◽  
Stress Strain ◽  
Elastic Plastic ◽  
Strain Behavior ◽  
Maximum Loading ◽  
Coupling Phenomena ◽  
Rapid Plastic Deformation

The characteristics of dynamic strength and fracture in structural steels and their welded joints particularly for pipelines should be evaluated based on the effects of the strain rate and service temperature. The temperature, however, rises so rapidly in structures due to the plastic work under the high strain rate such as ground sliding by earthquake when the effect of the temperature cannot be negligible for the dynamic fracture. It is difficult to predict or measure the temperature rise history with the corresponding stress-strain behavior, including the region beyond the uniform elongation, though the behavior at the large strain region after the maximum loading point is very important for the evaluation of fracture. In this paper, the coupling phenomena of the temperature and stress-strain fields under dynamic loading were simulated by using the finite element method. A modified rate-temperature parameter was defined by accounting for the effect of the temperature rise under rapid plastic deformation, and it was applied to the fully coupled analysis between the heat conduction and thermal elastic-plastic behavior. The temperature rise and stress-strain behavior, including the coupling phenomena, were studied including the region beyond the maximum loading point in structural steels and their undermatched joints, and then compared with the measured values.

Orowan-Based Deformation Model for Layered Metallic Materials

1996 ◽  
Vol 434 ◽  
Author(s):  
Eric R. Kreidler ◽  
Peter M. Anderson
Keyword(s):  
Plastic Layer ◽  
Deformation Model ◽  
Metallic Materials ◽  
Stress Strain ◽  
Dislocation Interaction ◽  
Line Energy ◽  
Elastic Plastic ◽  
Strain Behavior ◽  
Dislocation Pileups ◽  
Deformation Modes

AbstractAn Orowan-based deformation model for layered metallic materials is presented and used to calculate the stress-strain behavior for two deformation modes. This model assumes that layer thicknesses are sufficiently small so that single rather than multiple dislocation pileups form. Deformation then proceeds by increasing the density of single dislocation pileups. Furthermore, it is assumed that the controlling stress for plastic deformation is that to propagate a tunneling dislocation loop inside an embedded elastic-plastic layer. Initially, the resolved stress required to propagate an isolated tunneling loop does not depend on whether the loop shears the layer perpendicular to an interface or stretches it parallel to an interface. At larger strains, the tunneling arrays become sufficiently dense such that local dislocation interaction changes the line energy of a tunneling dislocation. As a result, the elastic-plastic layers may exhibit modest softening when sheared or substantial hardening when stretched. When the elastic-plastic layers are embedded into a multilayered specimen with alternating elastic-only layers, no macroscopic strain softening is observed. However, the predicted macroscopic stress-strain curves for stretching and shearing are significantly different in their dependence on layer thickness.

scholarly journals Shock wave speed and stress-strain relation of aluminium honeycombs under dynamic compression

2018 ◽  
Vol 183 ◽  
pp. 01047
Author(s):  
Peng Wang ◽  
Jun Zhang ◽  
Haiying Huang ◽  
Zhijun Zheng ◽  
Jilin Yu
Keyword(s):  
Shock Wave ◽  
Impact Velocity ◽  
Wave Speed ◽  
Dynamic Compression ◽  
Stress Strain ◽  
One Dimensional ◽  
Strain Relation ◽  
Stress Strain Relation ◽  
The One ◽  
The Impact

The propagation of layer-wise crushing bands in cellular materials under dynamic impact can be described by the plastic shock wave model. A cell-based finite element model of irregular aluminum honeycomb is constructed to carry out several constant-velocity compression tests. The shock wave speed is obtained by the one-dimensional stress distribution in the specimen along the loading direction. The relation between the shock wave speed and impact velocity is obtained and analyzed. It is found that the relation tends to be linear with the increase of the impact velocity. But the shock wave speed tends to be a constant value with the decrease of the impact velocity. A piecewise model is proposed to describe the dynamic stress-strain relation of aluminum honeycombs based on a piecewise hypothesis of the relation between the shock wave speed and the impact velocity together with the one-dimensional shock wave theory. Different stress-strain relations corresponding to different impact velocity regions and different deformation modes are obtained.

Unified Approach for Notch Stress Strain Conversion Rules

2013 ◽  
Vol 135 (4) ◽  
Author(s):  
R. Adibi-Asl ◽  
R. Seshadri
Keyword(s):  
Interpolation Method ◽  
Notch Root ◽  
Three Dimensional ◽  
Stress And Strain ◽  
Unified Approach ◽  
Stress Strain ◽  
Elastic Plastic ◽  
Strain Behavior ◽  
Notch Stress ◽  
Conversion Rules

There are several simplified methods, known as notch stress-strain conversion (NSSC) rules that provide an approximate formula to relate local elastic-plastic stresses and strains at the notch root to those estimated elastically. This paper investigates a unified approach that estimates nonlinear and history dependent stress-strain behavior of the notches using the conventional NSSC rules. A nonlinear interpolation method is adopted to estimate the elastic-plastic stress and strain at notches. A comparison is made between the finite element results for several notch configurations (with and without three-dimensional effects) and those obtained from NSSC rules and the proposed formulation.

scholarly journals Numerical study of one-dimensional compression of granular materials. I. Stress-strain behavior, microstructure, and irreversibility

2017 ◽  
Vol 95 (3) ◽  
Author(s):  
Mohamed Hassan Khalili ◽  
Jean-Noël Roux ◽  
Jean-Michel Pereira ◽  
Sébastien Brisard ◽  
Michel Bornert
Keyword(s):  
Granular Materials ◽  
Numerical Study ◽  
Stress Strain ◽  
One Dimensional ◽  
Strain Behavior
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