scholarly journals EVALUATING CONTACT STRESSES IN AN IMPACTOR PENETRATING A HARD SOIL

2020 ◽  
Vol 82 (1) ◽  
pp. 52-63
Author(s):  
E.Yu. Linnik
Keyword(s):  
Yield Criterion ◽  
Interaction Model ◽  
Shock Adiabat ◽  
Contact Stresses ◽  
Plasticity Condition ◽  
Soil Medium ◽  
Initial Strength ◽  
Hard Soil ◽  
Shockwave Front ◽  
Frozen Sandy Soil

Finite formulas have been derived for evaluating contact stresses in a rigid impactor penetrating a soil, taking into account the friction in the framework of the local interaction model. In analyzing dynamic deformation of the soil, its volumetric compressibility, shear resistance and initial strength are accounted for. The obtained evaluations of resistance to penetration of an impactor into the soil are based on a quadratic relation between the stress normal to the impactor surface and impact velocity. The authors have pioneered in deriving finite expressions for coefficients of a trinomial approximation as a function of experimentally determined physical-mechanical parameters of the soil - a dynamic compressibility diagram (a shock adiabat) and a yield strength - pressure diagram. Impact compressibility of soils is described based on Hugoniot's adiabat - a linear relation between shock wave velocity and mass velocity of the medium particles behind the shockwave front. Plastic deformation obeys the Mohr - Coulomb yield criterion with a constraint on the limiting value of maximal tangential stresses according to Tresca's criterion - the Mohr - Coulomb - Tresca plasticity condition. An earlier obtained analytical solution of a one-dimensional problem of a spherical cavity expanding at a constant velocity from a point in a half-space occupied by a plastic soil medium is used. A formula for determining critical pressure (a minimal pressure required for the formation of a cavity, accounting for internal pressure in the framework of Mohr - Coulomb's yield criterion) is also used, which generalizes a known solution for an elastic ideally plastic medium with Tresca's criterion. The derived formulas have been verified by comparing their results with the available data from experiments on the penetration of a steel conical impactor into a frozen sandy soil. It is shown that the disagreement between the numerical and experimental results is within 10%.

scholarly journals ANALYZING THE SPHERICAL CAVITY EXPANSION PROBLEM IN A MEDIUM WITH MOHR − COULOMB − TRESCA'S PLASTICITY CONDITION

2019 ◽  
Vol 81 (3) ◽  
pp. 292-304 ◽  
Author(s):  
V.L. Kotov ◽  
D.B. Timofeev
Keyword(s):  
Plastic Deformation ◽  
Analytical Solution ◽  
Spherical Cavity ◽  
Yield Criterion ◽  
Closed Form Solution ◽  
Cavity Expansion ◽  
Plasticity Condition ◽  
Rigid Plastic ◽  
Tangential Stresses ◽  
Shockwave Front

An analytical solution of the one-dimensional problem of a spherical cavity expanding at a constant velocity from a point in a space occupied by a plastic medium has been obtained. Impact compressibility of the medium is described using linear Hugoniot's adiabat. Plastic deformation obeys the Mohr - Coulomb yield criterion with constraints on the value of maximum tangential stresses according to Tresca's criterion. In the assumption of rigid-plastic deformation (the elastic precursor being neglected), incompressibility behind the shockwave front and the equality of the propagation velocities of the fronts of the plastic wave and the plane shockwave defined by linear Hugoniot's adiabat, a boundary-value problem for a system of two first-order ordinary differential equations for the dimensionless velocity and stress depending on the self-similar variable is formulated. A closed-form solution of this problem has been obtained in the form of a stationary running wave - a plastic shockwave propagating in an unperturbed half-space. This solution is a generalization of the earlier obtained analytical solution for a medium with the Mohr - Coulomb plasticity condition. The effect of constraining the limiting value of maximal tangential stresses on the distribution of dimensionless stresses behind the shockwave front has been examined. Formulas for determining the range of cavity expansion velocities, within which a simple solution for a medium with Tresca's plasticity condition is applicable, have been derived. The obtained solution can be used for evaluating resistance to high-velocity penetration of rigid strikers into low-strength soil media.

Thermomechanical Coupling of a Hyper-viscoelastic Truck Tire and a Pavement Layer and its Impact on Three-dimensional Contact Stresses

2021 ◽  
pp. 036119812110171
Author(s):  
Angeli Jayme ◽  
Imad L. Al-Qadi
Keyword(s):  
Contact Stress ◽  
Contact Area ◽  
Three Dimensional ◽  
Interaction Model ◽  
Rolling Resistance ◽  
Contact Stresses ◽  
Thermomechanical Coupling ◽  
Temperature Profiles ◽  
Near Surface ◽  
Truck Tire

A thermomechanical coupling between a hyper-viscoelastic tire and a representative pavement layer was conducted to assess the effect of various temperature profiles on the mechanical behavior of a rolling truck tire. The two deformable bodies, namely the tire and pavement layer, were subjected to steady-state-uniform and non-uniform temperature profiles to identify the significance of considering temperature as a variable in contact-stress prediction. A myriad of ambient, internal air, and pavement-surface conditions were simulated, along with combinations of applied tire load, tire-inflation pressure, and traveling speed. Analogous to winter, the low temperature profiles induced a smaller tire-pavement contact area that resulted in stress localization. On the other hand, under high temperature conditions during the summer, higher tire deformation resulted in lower contact-stress magnitudes owing to an increase in the tire-pavement contact area. In both conditions, vertical and longitudinal contact stresses are impacted, while transverse contact stresses are relatively less affected. This behavior, however, may change under a non-free-rolling condition, such as braking, accelerating, and cornering. By incorporating temperature into the tire-pavement interaction model, changes in the magnitude and distribution of the three-dimensional contact stresses were manifested. This would have a direct implication on the rolling resistance and near-surface behavior of flexible pavements.

Improvement of Methods of Calculation of Forces in Hot Strip Rolling

2020 ◽  
Vol 299 ◽  
pp. 577-581
Author(s):  
Georgy L. Baranov
Keyword(s):  
Rolling Force ◽  
Contact Stresses ◽  
Plasticity Condition ◽  
Neutral Position ◽  
Hot Strip Rolling ◽  
Strip Rolling ◽  
Normal Contact ◽  
Primary Stress ◽  
Hot Strip ◽  
Frictional Coefficients

A new solution Karman’s equation with the Mises plasticity condition is proposed for determining contact stresses in the slip zones for hot strip rolling. Replacement of the precise plasticity condition by an approximate condition in terms of primary stress leads to a substantial decrease in the length of slip zones and to increase of the rolling force. It was shown that, even at high frictional coefficients, the length of slip zones forms a significant part of the length of deformation region. On the basis of the obtained solutions the techniques for plotting curves of the normal contact stresses, determining the length of the slip zones, the neutral position of the cross section and rolling force refined.

scholarly journals MAPPROXIMATING STRESSES IN THE VICINITY OF A CAVITY EXPANDING AT A CONSTANT VELOCITY IN A MEDIUM WITH THE MOHR - COULOMB PLASTICITY CONDITION

2019 ◽  
Vol 81 (2) ◽  
pp. 177-190 ◽  
Author(s):  
V. L. Kotov
Keyword(s):  
Constant Velocity ◽  
Yield Criterion ◽  
Plastic Region ◽  
Plasticity Condition ◽  
Practical Applications ◽  
Plastic Yield ◽  
Runge Kutta Method ◽  
Wide Range ◽  
Self Similar Solution ◽  
Internal Friction Coefficient

A one-dimensional problem of a spherical cavity expanding at a constant velocity from a point in an infinite elastoplastic medium is considered. The problem has a first-kind self-similar solution. Elastoplastic deformation of the soil is described based on Hooke's law and the Mohr-Coulomb yield criterion. An analytical solution of the problem in the elastic region contacting with the plastic yield region has been obtained. To determine stress and velocity fields in the plastic region, a known algorithm, based on the shooting method, of analyzing a boundary-value problem for a system of two first-order ordinary differential equations, including the fourth-order Runge - Kutta method, has been realized. An effective algorithm of numerically analyzing an expanding cavity problem, earlier proposed in the works by М. Forrestal et al., makes it possible to solve the problem accurately enough for practical applications. A formula for determining the critical pressure - the minimal pressure required for the nucleation, accounting for internal pressure of a cavity in the framework of the Mohr - Coulomb yield criterion, has been derived, which is a generalization of the earlier published solution for an elastic ideally plastic medium with Tresca's criterion. The obtained critical value was compared with a numerical solution in a full formulation at the cavity expansion velocities close to zero in a wide range of variation of the parameters of the Mohr - Coulomb yield criterion. It is shown that the inaccuracy of the approximation of the proposed formula does not exceed 6% for the variation of the internal friction coefficient all over the admissible range, and for the initial value of the yield strength increasing by three orders of magnitude.

scholarly journals Plane strain – contact stress distribution beneath a rigid footing resting on a soft cohesive soil

1980 ◽  
Vol 17 (1) ◽  
pp. 114-122 ◽  
Author(s):  
A Patrick ◽  
S Selvadurai ◽  
R. Harland Kempthorne
Keyword(s):  
Stress Distribution ◽  
Plane Strain ◽  
Applied Stress ◽  
Contact Stress ◽  
Cohesive Soil ◽  
Contact Stresses ◽  
Soil Medium ◽  
Rigid Footing ◽  
Applied Stresses ◽  
Contact Stress Distribution

This note presents an experimental study of the plane strain – contact stress distribution beneath a rigid footing resting on a compacted soft cohesive soil medium. The immediate contact stress distribution was found to be highly dependent on the magnitude of the applied stress relative to the ultimate bearing capacity of the foundation. At low levels of applied stress the contact stresses were substantially higher at regions adjacent to the footing edges. As the applied stresses were increased, the contact stresses achieved a more uniform configuration.

scholarly journals Seismic Analysis of Circular Elevated Water Tank Designed by Indian Standard and European Standard Code

2021 ◽  
Vol 9 (10) ◽  
pp. 1638-1641
Author(s):  
Siddhnath Verma
Keyword(s):  
Soft Soil ◽  
Soil Conditions ◽  
Water Tank ◽  
Base Shear ◽  
European Standard ◽  
Soil Medium ◽  
Seismic Zones ◽  
Standard Code ◽  
Hard Soil ◽  
Elevated Water

Abstract: Elevated water tank is used for storage of water which is used for distribution to the public at certain pressure head. In high seismic zones the safety of water tank becomes point of great concern which in case of failure becomes very hazardous for public because of deficiency of water for public use and difficulty in putting fire away caused by earthquake. The water tank must be designed as much strong so that it can perform during and after earthquake without failing. The aim of this study is to design the elevated water tank as per Indian standard code and European standard code on ETABS software. In this study an elevated circular water tank of 35 m3 capacity is being designed in seismic zone III as per IS code and spectrum zone II as per Euro code for hard soil, medium soil and soft soil conditions. During analysis of tank the values of base moment, base shear, storey displacement and storey drift is being obtained and compared in both seismic zones for hard soil, medium soil and soft soil. Keywords: base shear, base moment, ETABS, elevated water tank.

scholarly journals Site characterizations of BMKG seismic network, Indonesia, based on HVSR analysis

2021 ◽  
Vol 873 (1) ◽  
pp. 012025
Author(s):  
Muzli Muzli ◽  
R A P Kambali ◽  
J Nugraha ◽  
S Sulastri ◽  
A R Hakim ◽  
...  
Keyword(s):  
Information Dissemination ◽  
Soft Soil ◽  
Spectral Ratio ◽  
Ratio Method ◽  
Waveform Data ◽  
Soil Medium ◽  
The Public ◽  
Seismic Waveform ◽  
Site Characteristics ◽  
Hard Soil

Abstract In the last few years BMKG (Agency for Meteorology Climatology and Geophysics) has increased the number of seismic stations significantly. Until mid-2020, when this study was conducted, the number of BMKG stations has reached 339 units. Development of the network is aimed to improve the data quality, speed of earthquake data processing and information dissemination to the public, accuracy of the hypocenter, as well as the magnitude. The objective of this study is to identify the site characteristics of the network. We analysed the noise recorded at BMKG stations throughout Indonesia using the HVSR (Horizontal to Vertical Spectral Ratio) method. The results of HVSR analysis were used to classify the site conditions of each station. We got the number of stations with the classification of hard rock, rock, hard soil, medium soil, and soft soil, 47, 57, 52, 30, and 84, respectively. This site condition represents the stations characteristics and affects the quality of seismic waveform data.

Ballistic Impact Characteristics of Flat-nose Projectile Penetrating Concrete and Soil Compound Target

2012 ◽  
Vol 13 (3-4) ◽  
Author(s):  
Yongxiang Dong ◽  
Shunshan Feng ◽  
Guangyan Huang ◽  
Chunmei Liu ◽  
Lixing Xiao ◽  
...  
Keyword(s):  
Soil Layer ◽  
Ballistic Impact ◽  
Low Velocity ◽  
Soil Medium ◽  
Damage And Failure ◽  
Finite Element Software ◽  
Hard Soil ◽  
Impact Characteristics ◽  
Crush Zone ◽  
Compound Target

AbstractBallistic impact characteristics on the flat-nose projectile penetrating the concrete and soil compound target are studied. The deformation process and failure zone in the target are described by numerical simulation with finite element software. The results show that penetration depth, residual velocity and deceleration amplitude of flat-nose projectile increase with initial velocity. The features of concrete target after impact are approximately in agreement with experimental results. And the cracks and the tensile crush zone formed during penetration could characterize the damage and failure of target. Meanwhile, terminal ballistic characteristics of flat-nose projectile into single soil layer are studied to compare with that of concrete compound target. The results show that the overload of projectile penetrating hard-soil is only one-third of that of concrete compound target with low velocity. Reversely, the duration of the former is more than five times as long as the latter, and the rebound velocity of projectile penetrating soil medium is greater than the concrete compound target.

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