scholarly journals Non-Classical Model of Dynamic Behavior of Concrete

2019 ◽  
Vol 9 (13) ◽  
pp. 2590 ◽  
Author(s):  
Adam Stolarski ◽  
Waldemar Cichorski ◽  
Anna Szcześniak
Keyword(s):  
Dynamic Properties ◽  
Load Capacity ◽  
Classical Model ◽  
Dynamic Strength ◽  
Strength Criterion ◽  
Theoretical Models ◽  
Limited Range ◽  
Plastic Properties ◽  
Perfectly Plastic ◽  
Softening Material

Modeling of dynamic properties of concrete is presented in the paper. The non-classical model of dynamic deformation was proposed. The essence of this model is the method of determination of the initial dynamic yield surface. For this purpose, the dynamic strength criterion was used. The model describes the elastic properties until attaining the dynamic strength of concrete, perfectly plastic properties in the limited range of deformation, material softening, material dilatation, and cracking or crushing of material as the residual stress processes during tension or compression. Degradation of elastic material constants was taken into consideration. Comparative analysis with previously published experimental results and theoretical models demonstrated that the proposed model is well approximates the basic dynamic properties of concrete and can be used in numerical analysis to evaluate the dynamic load capacity of reinforced concrete structures.

Study on the Dynamic Performance of Asphalt Concrete under Passive Confined Pressure

2012 ◽  
Vol 226-228 ◽  
pp. 1755-1759
Author(s):  
Hua Zhang ◽  
Fei Li ◽  
Yu Wei Gao
Keyword(s):  
Elastic Modulus ◽  
Asphalt Concrete ◽  
Poisson Ratio ◽  
Dynamic Properties ◽  
Dynamic Performance ◽  
Dynamic Strength ◽  
Confining Pressure ◽  
Mechanical Behaviors ◽  
One Dimensional ◽  
Stress States

An improved passive confining pressure SHPB method was used to study the dynamic mechanical behaviors of asphalt concrete under quasi-one dimensional strain state. The effect of confining jacket material and its geometrical sizes on the confining pressure were discussed. The dynamic strength, dynamic modulus of elasticity and dynamic Poisson ratio of asphalt concrete were obtained. The influential rules of confining pressure on the dynamic properties were studied by comparing the stress-strain curves of asphalt concrete under different stress states. The study found that passive confining greater impact on the strength of asphalt concrete than elastic modulus and Poisson ratio, but the elastic modulus improved with the increase of confining pressure.

ELASTO-PLASTIC PROPERTIES OF Mo-MODIFIED Ti DEDUCED FROM INDENTATION TESTS AND FINITE ELEMENT ANALYSIS

2019 ◽  
Vol 26 (07) ◽  
pp. 1850225
Author(s):  
YONG MA ◽  
ZHAO YANG ◽  
SHENGWANG YU ◽  
BING ZHOU ◽  
HONGJUN HEI ◽  
...  
Keyword(s):  
Finite Element ◽  
Surface Treatment ◽  
Load Capacity ◽  
Indentation Test ◽  
Element Analysis ◽  
Plastic Properties ◽  
Polynomial Expression ◽  
Indentation Tests ◽  
Graded Material ◽  
Micro Indentation

The aim of this paper is to establish an approach to quantitatively determine the elasto-plastic parameters of the Mo-modified Ti obtained by the plasma surface alloying technique. A micro-indentation test is conducted on the surface under 10[Formula: see text]N. Considering size effects, nanoindentation tests are conducted on the cross-section with two loads of 6 and 8[Formula: see text]mN. Assuming nanoindentation testing sublayers are homogeneous, finite element reverse analysis is adopted to determine their plastic parameters. According to the gradient distributions of the elasto-plastic parameters with depth in the Mo-modified Ti, two types of mathematical expressions are proposed. Compared with the polynomial expression, the linear simplified expression does not need the graded material to be sectioned and has practical utility in the surface treatment industry. The validation of the linear simplified expression is verified by the micro-indentation test and corresponding finite element forward analysis. This approach can assist in improving the surface treatment process of the Mo-modified Ti and further enhancing its load capacity and wear resistance.

scholarly journals Composite Single-Bolted Joint Simulation for Dynamic Strength Prediction

Proceedings ◽  
2018 ◽  
Vol 2 (8) ◽  
pp. 512
Author(s):  
Zeliang Yu ◽  
Pu Xue ◽  
Yue Chen
Keyword(s):  
Composite Structures ◽  
Dynamic Properties ◽  
Dynamic Strength ◽  
Structural Deformation ◽  
Engineering Practice ◽  
Three Dimension ◽  
Bolted Joint ◽  
Finite Element Software ◽  
Composite Joint ◽  
Significant Difference

Composite material has been widely used in various fields for its high specific strength and high specific stiffness, so the connectors applicable to composite structures capture many researchers’ attention. With the advantages of higher carrying capacity and repetitive assembling and disassembling, bolted joint becomes one of the most popular connectors in engineering practice. Cutting off the fiber and causing stress concentration are more serious to composite than metal, so it is necessary to predict the strength of the composite joints. Most investigations focus on the response under quasi-static loading, while dynamic effects should be in consideration in increasing impact conditions. The dynamic mechanical properties of composite joint may have a significant impact on the structural deformation and damage modes. For this purpose, this paper conducts dynamic composite single-bolted joint simulations in ABAQUS/Explicit, which used for predicting dynamic strength of the composite joint. T800/X850 laminates were tested to investigate their dynamic properties in our lab. Then the three-dimension progression damage model was established, while the dynamic constitutive model, damage initial criteria and damage evolution law of composite materials were coded in VUMAT of the finite element software ABAQUS/Explicit. The model was validated by quasi-static experiments of composite joint. The simulation results indicate that the yield strength and ultimate strength of the single-bolted composite joint are obviously increasing when consider the strain rate effect and dynamic loading. And the load-displacement curves show significant difference in damage stage. The main damages are sub-layer buckling and fiber breakage caused by extrusion.

On the Axisymmetric Response of a Damaged Flexible Pipe

2014 ◽  
Author(s):  
José Renato M. de Sousa ◽  
Carlos Magluta ◽  
Ney Roitman ◽  
George C. Campello
Keyword(s):  
Finite Element ◽  
Analytical Model ◽  
Load Capacity ◽  
High Stress ◽  
Experimental Tests ◽  
Theoretical Models ◽  
Experimental Measurements ◽  
Fe Model ◽  
Flexible Pipe ◽  
High Stress Concentration

This work focuses on the structural analysis of a damaged 9.13″ flexible pipe to pure and combined axisymmetric loads. A set of experimental tests was carried out considering one up to ten broken wires in the outer tensile armor of the pipe and the results obtained are compared to those provided by a previously presented finite element (FE) model and a traditional analytical model. In the experimental tests, the pipe was firstly subjected to pure tension and, then, the responses to clockwise and anti-clockwise torsion superimposed with tension were investigated. In these tests, the induced strains in the outer armor were measured. Moreover, the axial elongation of the pipe was monitored when the pipe is subjected to tension, whilst the twist of the pipe was measured when torsion is imposed. The experimental results pointed to a slight decrease in the stiffness of the pipe with the increasing number of broken wires and, furthermore, a redistribution of forces among the intact wires of the damaged layer with high stress concentration in the wires close to the damaged ones. Both theoretical models captured these features, but, while the results obtained with the FE model agreed well with the experimental measurements, the traditional analytical model presented non-conservative results. Finally, the results obtained are employed to estimate the load capacity of the pipe.

scholarly journals Survivability of the locomotive cabin at interval estimation of obstacle parameters

2018 ◽  
Vol 216 ◽  
pp. 02021
Author(s):  
Alexander Smolyaninov ◽  
Igor Emel'yanov ◽  
Vladimir Mironov ◽  
Alexei Kuznetsov ◽  
Vasily Lapshin
Keyword(s):  
Finite Element ◽  
Interval Estimation ◽  
Dynamic Strength ◽  
Elastic Interaction ◽  
Strength Criterion ◽  
Structural Elements ◽  
The Finite Element Method ◽  
Initial State ◽  
Calculation Results ◽  
Speed Regime

The article considers the multiparameter problem of the mechanical system behavior and its survivability when destructing individual elements. The technique for constructing the area of safe operation of the cabin of the GT1-h gas turbine locomotive was illustrated on the example of collision of a locomotive with an obstacle at a crossing. The main parameters determining the energy of interaction between the cabin and the obstacle was singled out, and their influence on the survivability of the structure was analyzed. The finite element method was used to calculate the load-bearing capacity of a power frame with a buffer device in the initial state and after the destruction of individual structural elements by the dynamic strength criterion. The force of elastic interaction between the locomotive and the obstacle was estimated through the spring, the rigidity of which was estimated on the basis of the finite element calculation results. As a result of the calculations, proposals were developed to strengthen the cabin frame to ensure the safety of the crew and the instrument part in case of unauthorized collision with an obstacle of considerable mass and violation of the speed regime.

Reduction of the Dynamic Load Capacity in a Squeeze Film Damper Operating With a Bubbly Lubricant

1999 ◽  
Vol 121 (4) ◽  
pp. 703-709 ◽  
Author(s):  
S. E. Diaz ◽  
L. A. San Andre´s
Keyword(s):  
Volume Fraction ◽  
Load Capacity ◽  
Effective Means ◽  
Theoretical Models ◽  
Operating Conditions ◽  
Qualitative Description ◽  
Squeeze Film ◽  
Damping Force ◽  
Hydrostatic Force ◽  
Discharge Pressure

Squeeze film dampers (SFDs) are effective means to reduce vibrations and to suppress instabilities in rotor-bearing systems. However, at operating conditions while traversing critical speeds with large orbital whirl motions, ingestion and entrapment of air into the thin lands of SFDs generates a bubbly mixture (air in lubricant) that is known to reduce the dynamic film pressures and the overall damping capability. This pervasive phenomenon lacks proper physical understanding and sound analytical modeling. An experimental investigation to quantify the forced performance of a SFD operating with a controlled bubbly mixture is detailed. Tests are conducted in a constrained circular orbit SFD to measure the dynamic squeeze film pressures and journal motion at two whirl frequencies (8.33 and 16.67 Hz) as the air content in the mixture increases from 0 percent to 100 percent. The analysis of period-averaged film pressures reveals a zone of uniform low pressure of magnitude equal to the discharge pressure, independently of the mixture composition. The uniform pressure zone extends as the mixture void fraction increases. Radial and tangential film forces are estimated from the dynamic pressures at two axial locations of measurement. The tangential (damping) force decreases proportionally with the mixture volume fraction, while a radial hydrostatic force remains nearly invariant. The experimental results quantify effects previously known by qualitative description only, thus providing a benchmark towards the development of sound theoretical models.

Assessment of Redundant Steel Structural Systems Considering Effects of Member Strength Variability on the System

2012 ◽  
Vol 267 ◽  
pp. 33-41
Author(s):  
Amanullah Rasooli ◽  
Hideki Idota
Keyword(s):  
Random Variable ◽  
Structural Systems ◽  
Deformation Capacity ◽  
Plastic Properties ◽  
Perfectly Plastic ◽  
Combination System ◽  
Statistical Behavior ◽  
Essential Parameter ◽  
Strength Variability ◽  
Mcs Method

In the present study, the failure of basic redundant steel structural systems is investigated. By considering that each member of the system has brittle, semi-brittle, or perfectly plastic properties, the statistical behavior of perfectly brittle systems, semi-brittle systems, perfectly plastic and combination systems are evaluated, and the effects of the coefficient of variation (CoV) of members on the systems are investigated. Uncorrelated strengths with the same mean are considered for the system elements. By using the Monte Carlo simulation (MCS) method, maximum strength, yield strength and residual strength of the redundant steel structural systems are evaluated. The CoV of member strength is an essential parameter for statistical assessment of steel structural systems. In this study, the strength is defined random variable a selected normal distribution represents the random variable, for the member strength. The deformation capacity of the member is strongly depends to the characteristics of member strength, but the post failure factor has deterministic values, only for the combination system. The post failure factor is a random variable that represents the uncertainty, uniform distribution is selected to represents random variable, in combination system post failure factor.

Forming of Automotive Parts with Nuts Clinch Process in Comparison to Welding of Nuts

2014 ◽  
Vol 611-612 ◽  
pp. 1503-1510
Author(s):  
Pawel Balon ◽  
Andrzej Świątoniowski
Keyword(s):  
Mass Production ◽  
High Strength Steels ◽  
Dynamic Strength ◽  
High Strength ◽  
Plastic Properties ◽  
Joining By Forming ◽  
Automotive Parts ◽  
Set Up ◽  
Increased Strength

In this paper authors present joining by forming method for screws and nuts. Self-clinching nut process was compared to a traditional nut welding method after drawing the requested shape in order to analyse quality of junction. That process is very often carried out for High Strength Steels which usually contain decreased plastic properties and increased strength. It usually causes a problem to set up the self-clinching process. Currently, there are a few companies specialising only in this kind of processes, however correct designing of such tool requires taking into account many factors such as choose of joining method by forming and proper connector type. Despite many difficulties, this method allows for joining hard welded steels and most of all for minimization of operations amount in mass production. Operations of joining by forming of nuts and screws, gives significant savings of anticipated costs with simultaneously guarantees high static and dynamic strength.

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