Elasto-Plastic Model of a Seismic Energy–Dissipating Device

2007 ◽  
Vol 23 (3) ◽  
pp. 571-583 ◽  
Author(s):  
Ricardo Chicurel
Keyword(s):  
Cross Section ◽  
Applied Load ◽  
Seismic Energy ◽  
Contact Forces ◽  
Experimental Results ◽  
Bending Moments ◽  
Plastic Model ◽  
Small Increments ◽  
Energy Dissipating Device ◽  
Rigid Walls

A model of a seismic energy–dissipating device is formulated. The dissipating element is a U-shaped strip that undergoes a large rolling-bending deformation while confined between parallel rigid walls. The strip is divided into a number of rigid elements pivoted to one another in a chainlike fashion. A step-by-step solution is developed by considering small increments in the applied load. Increments in the bending moments arising at the pivots are expressed in terms of the changes in the angles between adjoining elements on the basis of corresponding changes in stresses acting on discrete strips into which the cross-section is divided. The stresses are calculated by means of a bilinear elasto-plastic model. The solution keeps track of the points at which contact forces with the constraining walls are developed. Examples are worked out resulting in hysteretic cycles that are compared with published experimental results.

Experimental Studies Of Multilayer Glass Structures On Compression, Compression With Bending And Simple Bending

2019 ◽  
pp. 22-30
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Applied Load ◽  
Experimental Studies ◽  
Strength Properties ◽  
Research Topic ◽  
Normative Values ◽  
Laminated Glass ◽  
The Cross ◽  
Experimental Values

The work of multilayer glass structures for central and eccentric compression and bending are considered. The substantiation of the chosen research topic is made. The description and features of laminated glass for the structures investigated, their characteristics are presented. The analysis of the results obtained when testing for compression, compression with bending, simple bending of models of columns, beams, samples of laminated glass was made. Overview of the types and nature of destruction of the models are presented, diagrams of material operation are constructed, average values of the resistance of the cross-sections of samples are obtained, the table of destructive loads is generated. The need for development of a set of rules and guidelines for the design of glass structures, including laminated glass, for bearing elements, as well as standards for testing, rules for assessing the strength, stiffness, crack resistance and methods for determining the strength of control samples is emphasized. It is established that the strength properties of glass depend on the type of applied load and vary widely, and significantly lower than the corresponding normative values of the strength of heat-strengthened glass. The effect of the connecting polymeric material and manufacturing technology of laminated glass on the strength of the structure is also shown. The experimental values of the elastic modulus are different in different directions of the cross section and in the direction perpendicular to the glass layers are two times less than along the glass layers.

Determination of collapse moment of different angled pipe bends with initial geometric imperfection subjected to in-plane bending moments

2021 ◽  
pp. 095440622199640
Author(s):  
Manish Kumar ◽  
Pronab Roy ◽  
Kallol Khan
Keyword(s):  
Finite Element ◽  
Cross Section ◽  
Circular Cross Section ◽  
Initial Imperfection ◽  
Bend Angle ◽  
Bending Moments ◽  
Element Analysis ◽  
Geometric Imperfection ◽  
Initial Geometric Imperfection

From the recent literature, it is revealed that pipe bend geometry deviates from the circular cross-section due to pipe bending process for any bend angle, and this deviation in the cross-section is defined as the initial geometric imperfection. This paper focuses on the determination of collapse moment of different angled pipe bends incorporated with initial geometric imperfection subjected to in-plane closing and opening bending moments. The three-dimensional finite element analysis is accounted for geometric as well as material nonlinearities. Python scripting is implemented for modeling the pipe bends with initial geometry imperfection. The twice-elastic-slope method is adopted to determine the collapse moments. From the results, it is observed that initial imperfection has significant impact on the collapse moment of pipe bends. It can be concluded that the effect of initial imperfection decreases with the decrease in bend angle from 150∘ to 45∘. Based on the finite element results, a simple collapse moment equation is proposed to predict the collapse moment for more accurate cross-section of the different angled pipe bends.

The influence of the nuclear and atomic form factors on the muon bremsstrahlung cross section

1968 ◽  
Vol 46 (10) ◽  
pp. S377-S380 ◽  
Author(s):  
A. A. Petrukhin ◽  
V. V. Shestakov
Keyword(s):  
Form Factor ◽  
Cross Section ◽  
Born Approximation ◽  
Form Factors ◽  
Experimental Results ◽  
Simple Analytical Expression ◽  
Nuclear Form Factor ◽  
The Cross ◽  
Atomic Electrons ◽  
Bremsstrahlung Process

The cross section for the muon bremsstrahlung process is calculated as a function of the nuclear form factor in the Born approximation following the Bethe and Heitler theory. The influence of the nuclear form factor is greater than that taken by Christy and Kusaka. The simple analytical expression for the effect of the screening of the atomic electrons is found. The influence of a decrease in the cross section upon the interpretation of some experimental results is estimated.

The Use of Strain Energy and Fracture Correlation to Determine Life Expectancy for Notched Components

2009 ◽  
Author(s):  
Onome Scott-Emuakpor ◽  
Tommy George ◽  
Charles Cross ◽  
M.-H. Herman Shen
Keyword(s):  
Fatigue Life ◽  
Stress Concentration ◽  
Cross Section ◽  
Strain Energy ◽  
Notch Root ◽  
Stress Gradient ◽  
Strain Curve ◽  
Experimental Results ◽  
Cyclic Process ◽  
Notched Components

An energy-based method for predicting fatigue life of half-circle notched specimens, based on the nominal applied stress amplitude, has been developed. This developed method is based on the understanding that the total strain energy dissipated during a monotonic fracture and a cyclic process is the same material property, where the density of each can be determined by measuring the area underneath the monotonic true stress-strain curve and measuring the sum of the area within each Hysteresis loop in the cyclic process, respectively. Using this understanding, the criterion for determining fatigue life prediction of half-circle notched components is constructed by incorporating the stress gradient effect through the notch root cross-section. Though fatigue at a notch root is a local phenomenon, evaluation of the stress gradient through the notch root cross-section is essential for incorporating this method into finite element analysis minimum potential energy process. The validation of this method was carried out by comparison with both notched and unnnotched experimental fatigue life of Aluminum 6061-T6 (Al 6061-T6) specimens under tension/compression loading at the theoretical notch fatigue stress concentration factor of 1.75. The comparison initially showed a slight deviation between prediction and experimental results. This led to the analysis of strain energy density per cycle up to failure, and an improved Hysteresis representation for the energy-based prediction analysis. With the newly developed Hysteresis representation, the energy-based prediction comparison shows encouraging agreement with unnotched experimental results and a theoretical notch stress concentration value.

Stresses in compact end closures for cylindrical pressure vessels

1969 ◽  
Vol 4 (1) ◽  
pp. 57-64
Author(s):  
R W T Preater
Keyword(s):  
Cylindrical Shell ◽  
Rigid Body ◽  
Optimum Design ◽  
Cross Section ◽  
Experimental Verification ◽  
Pressure Vessels ◽  
Rigid Body Motion ◽  
Experimental Results ◽  
Body Motion ◽  
Annular Ring

Three different assumptions are made for the behaviour of the junction between the cylindrical shell and the end closure. Comparisons of analytical and experimental results show that the inclusion of a ‘rigid’ annular ring beam at the junction of the cylider and the closure best represents the shell behaviour for a ratio of cylinder mean radius to thickness of 3–7, and enables a prediction of an optimum vessel configuration to be made. Experimental verification of this optimum design confirms the predictions. (The special use of the term ‘rigid’ is taken in this context to refer to a ring beam for which deformations of the cross-section are ignored but rigid body motion is permitted.)

Behavior of porosity in billet during rolling process of rail

2019 ◽  
Vol 116 (6) ◽  
pp. 607 ◽  
Author(s):  
Rong Cheng ◽  
Jiongming Zhang ◽  
Liangjin Zhang ◽  
Haitao Ma
Keyword(s):  
Simulation Model ◽  
Cross Section ◽  
Rolling Process ◽  
Experimental Results ◽  
Short Cracks ◽  
Industrial Experiments ◽  
Isosceles Trapezoid ◽  
The Cross

Unlike traditional rolling processes, reduction of rolling process of rail is along two vertical directions and the broadening of rolled piece is controlled. In this study, industrial experiments and a simulation model of the rolling process of rail were conducted to investigate the behaviors of porosities in billet during the rolling process of rail. The experimental and simulated results revealed that porosities moved toward the center on the cross section of the rolled piece and the porosities region reduced from a rectangle with the size (76.7 × 93.3 mm) to an isosceles trapezoid with the size {(12.8 + 18.5 mm) × 47.2 mm} during the rolling process of rail. The shapes of the porosities changed from circles with the diameters smaller than 6 mm to short cracks with the lengths shorter than 10 mm on the cross section. The two vertical reduction directions and the controlled broadening of rolled piece both counted against the closure of porosity. The simulated results were mostly in agreement with the experimental results.

scholarly journals Assessing the Instantaneous Stiffness of Cracked Reinforced Concrete Beams Based on a Gradual Change in Strain Distributions

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Chunyu Fu ◽  
Dawei Tong ◽  
Yuyang Wang
Keyword(s):  
Experimental Data ◽  
Reinforced Concrete ◽  
Cross Section ◽  
Concrete Beams ◽  
Internal Force ◽  
Experimental Results ◽  
Reinforced Concrete Beams ◽  
Gradual Change ◽  
Concrete Cracking ◽  
Good Agreement

Concrete cracking causes a gradual change in strain distributions along the cross section height of reinforced concrete beams, which will finally affect their instantaneous stiffness. A method for assessing the stiffness is proposed based on the gradual change, which is considered through modeling different strain distributions for key sections in cracked regions. Internal force equilibria are adopted to find a solution to top strains and neutral axes in the models, and then the inertias of the key sections are calculated to assess the beam stiffness. The proposed method has been validated using experimental results obtained from tests on five reinforced concrete beams. The predicted stiffness and displacements are shown to provide a good agreement with experimental data. The instantaneous stiffness is proven to greatly depend on the crack number and depth. This dependence can be exactly reflected by the proposed method through simulating the gradual change in concrete strain distributions.

scholarly journals Guided Wave Propagation in Detection of Partial Circumferential Debonding in Concrete Structures

Sensors ◽  
2019 ◽  
Vol 19 (9) ◽  
pp. 2199 ◽  
Author(s):  
Beata Zima
Keyword(s):  
Reinforced Concrete ◽  
Cross Section ◽  
Wave Velocity ◽  
Guided Waves ◽  
Concrete Structures ◽  
Circular Cross Section ◽  
Guided Wave ◽  
Experimental Results ◽  
Reinforced Concrete Beams ◽  
Average Wave

The following article presents results of investigating the damage detection in reinforced concrete beams with artificially introduced debonding between the rod and cover, using a non-destructive method based on elastic waves propagation. The primary aim of the research was to analyze the possible use of guided waves in partial circumferential debonding detection. Guided waves were excited and registered in reinforced concrete specimens with varying extents of debonding damage by piezoelectric sensors attached at both ends of the beams. Experimental results in the form of time–domain signals registered for variable extent of debonding were compared, and the relationships relating to the damage size and time of flight and average wave velocity were proposed. The experimental results were compared with theoretical predictions based on dispersion curves traced for the free rod of circular cross-section and rectangular reinforced concrete cross-section. The high agreement of theoretical and experimental data proved that the proposed method, taking advantage of average wave velocity, can be efficiently used for assessing debonding size in reinforced concrete structures. It was shown that the development of damage size in circumferential direction has a completely different impact on wave velocity than development of debonding length. The article contains a continuation of work previously conducted on the detection of delamination in concrete structures. The proposed relationship is the next essential step for developing a diagnostics method for detecting debondings of any size and orientation.

Influence of Elastic-Plastic Bending on the Relationship Between Applied Load and Maximum Bending Stress for Straight and Curved Bars

2020 ◽  
Author(s):  
Don Metzger
Keyword(s):  
Plastic Strain ◽  
Plastic Zone ◽  
Yield Point ◽  
Cross Section ◽  
Applied Load ◽  
Bending Stress ◽  
Stress Strain ◽  
Bending Load ◽  
Bending Capacity ◽  
The Relationship

Abstract Bending capacity in excess of the load required to cause yielding is due to a combination of work hardening and the effect of the plastic zone spreading toward the neutral axis. For materials of sufficiently high ductility, a fully developed plastic zone is achieved and the bulk of the section is stressed beyond yield. For lower ductility materials, failure may occur prior to full development of the plastic zone such that only a fraction of the cross section is at or above the yield stress. In such cases, the relationship between applied load and maximum bending stress becomes sensitive to the shape of the stress-strain curve near the yield point. This relationship is examined for straight and curved bars of rectangular and trapezoidal cross-section for tensile stress-strain curves characterized by nonlinear functions. The stress distribution as a function of applied load is determined analytically by enforcing moment equilibrium across the section. The strain distribution is determined through the classical condition of “planes remain plane” during deformation. The solutions provide analytically smooth load curves such that maximum stress can be directly plotted as a function of applied load. These plots exhibit three distinct regimes of response: 1) elastic, 2) development of plastic zone, and 3) fully developed plastic zone. Since the response is analytically smooth, the detailed relationship through the knee of the tensile curve can be examined. The results indicate that bending capacity is influenced significantly by the development of small amounts of plastic strain prior to reaching a yield point defined by the usual 0.2% plastic strain offset method. The results also show how loss of ductility with respect to tensile elongation translates into reduced bending load capacity in a non-linear relationship.

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