scholarly journals Behavior of concrete-filled double skin steel tubular columns under eccentric compression after fire

Author(s):  
Xiao Liu ◽  
Jianye Xu ◽  
Bing Wang

Abstract: To analysis the behavior of the mechanical properties of concrete-filled double skin steel tubular (CFDST) columns under eccentric loads after fire, the finite element analysis was used. The established FEA modeling was verified by the experimental results which has a good agreement. The FEA modeling was then used to perform the temperature field and the full-range load-deformation relations of the CFDST subject to eccentric compression after exposed to fire. The results indicate that: with the time of fire increasing, the eccentric distance increasing, the steel ratio decreasing, the yield strength decreasing and compressive strength decreasing, the bearing capacity of CFDST in circle section under eccentric loads is showing a decrease trend, and the stiffness of component decreases with the time of fire increasing, the eccentric distance increasing and the steel ratio decreasing. The ductility of CFDST became better with the time of fire increasing and the eccentric distance increasing.

2013 ◽  
Vol 739 ◽  
pp. 131-135
Author(s):  
Li Han Zhang ◽  
Ke Sheng Wang ◽  
Yu Han ◽  
Jia Yu Ying

Parallel extrusion is a combined extrusion process for forming round-fin heat sink on thick metal sheets. In this paper, the parallel extrusion has been applied to manufacture the round-fin heat sink in the automotive lighting. Numerical simulations on the round-fin heat sink forming using the software DEFORM were carried out. The tooling structure with counterpressure on the heat sink formation was investigated. The results show that the tooling structure with counterpressure is helpful to the formation of round-fin heat sink, which not only ensures the height of each round-fin on the heat sink is uniform but also retards the initiation of flow-through on the reverse side of round-fin. In addition, the experiments of press forging process were conducted to validate the finite element analysis, it is shown that the friction at the punch-blank interface has more significant effect on preventing the initiation of flow-through compared with the friction at the die-blank interface, which implies that the punch-blank interface has more significant effect on the material flow in the formation of round-fin, and the simulation results are in good agreement with the experimental data.


Author(s):  
C. H. Richter ◽  
U. Krupp ◽  
M. Zeißig ◽  
G. Telljohann

Slender turbine blades are susceptible to excitation. Resulting vibrations stress the blade's fixture to the rotor or stator. In this paper, high cycle fatigue at the edge of contact (EOC) between blade and rotor/stator of such fixtures is investigated both experimentally and numerically. Plasticity in the contact zone and its effects on, e.g., contact tractions, fatigue determinative quantities, and fatigue itself are shown to be of considerable relevance. The accuracy of the finite element analysis (FEA) is demonstrated by comparing the predicted utilizations and slip region widths with data gained from tests. For the evaluation of EOC fatigue, tests on simple notched specimens provide the limit data. Predictions on the utilization are made for the EOC of a dovetail setup. Tests with this setup provide the experimental fatigue limit to be compared to. The comparisons carried out show a good agreement between the experimental results and the plasticity-based calculations of the demonstrated approach.


2013 ◽  
Vol 135 (2) ◽  
Author(s):  
Dianyin Hu ◽  
Rongqiao Wang ◽  
Guicang Hou

A new lifetime criterion for withdrawal of turbine components from service is developed in this paper based on finite element (FE) analysis and experimental results. Finite element analysis is used to determine stresses in the turbine component during the imposed cyclic loads and analytically predict a fatigue life. Based on the finite element analysis, the critical section is then subjected to a creep-fatigue test, using three groups of full scale turbine components, attached to an actual turbine disc conducted at 750 °C. The experimental data and life prediction results were in good agreement. The creep-fatigue life of this type of turbine component at a 99.87% survival rate is 30 h.


1990 ◽  
Vol 112 (3) ◽  
pp. 267-271 ◽  
Author(s):  
O. M. Ettouney ◽  
K. A. Stelson

This paper addresses an approach to calculate the friction coefficient during nonuniform compression of cylinders. The approach combines new friction-calibration curves (prepared using the finite-element analysis) that relate friction to workpiece shape and the foldover model from Part I. Foldover in upsetting is used in the same way that the change in internal diameter is used in the ring test to determine friction. However, the new approach has the advantage that measurements are taken directly from the workpiece. Comparisons of friction values calculated from the ring test and the new approach showed good agreement.


Author(s):  
Zhaochun Yang ◽  
Qing-Ming Wang ◽  
Patrick Smolinski ◽  
Hongbo Yang

On-chip microaccelerometers using piezoelectric thin films has attracted much interest due to their simple structure and potentially high sensitivity. However, the relationships between the structure of the microaccelerometer and its performance still need to be further developed in more details. In this paper we present a theoretical model for a microaccelerometer with four suspended flexural PZT/silicon beams and a central proof mass configuration. The model takes into account the effect of device geometry and elastic properties of the piezoelectric film, and is supported by the finite element analysis. The good agreement of the results demonstrates the validity of the modeling assumptions. This study shows that the accelerometer sensitivity decreases with increasing the width and thickness of the bilayer beams, and elastic modulus of the mechanical microstructure, while increasing the length of the beam, increases sensitivity. For a fixed beam thickness, a maximum sensitivity exists for appropriate PZT/Si thickness. In addition, it is found that the sensitivity is also proportional to the magnitude of the input acceleration. The results of this study can be readily applied to for on-chip piezoelectric microaccelerometer design and its structural optimization.


2014 ◽  
Vol 893 ◽  
pp. 314-319
Author(s):  
P. Gurusamy ◽  
S. Balasivanandha Prabu ◽  
R. Paskaramoorthy

This paper discusses the influence of die temperature on the solidification behaviour of A356/SiCp composites fabricated by squeeze casting method. Information on the solidification studies of squeeze cast composites is somewhat scarce. Experiments were carried out by varying the die temperatures for cylindrical shaped composite castings K-type thermocouples were interfaced to the die and the temperature-time history was recorded to construct the cooling curves. The cooling curves are also predicted from the finite element analysis (FEA) software ANSYS 13. The experimental and predicted cooling curves are not in good agreement. In addition to, the experimental and theoretical solidification times are studied. It was understood that the increase in the die temperature decreases the cooling rate.


2002 ◽  
Vol 124 (2) ◽  
pp. 325-331 ◽  
Author(s):  
G. B. Sinclair ◽  
N. G. Cormier

Simple physical models for the stresses in dovetail attachments are developed. These models address: to slip or not to slip, nominal stresses during loading up, peak contact and shear stresses during loading up, hoop stresses during loading up, peak contact and shear stresses during unloading, and hoop stresses during unloading. Comparisons are made with a previous paper on companion finite element modeling. Generally there is good agreement between the simple physical models and the finite element analysis. Together the two identify a pinching mechanism as leading to large fluctuations in hoop stresses at the edges of contact. These fluctuating hoop stresses can be expected to be a major contributor to the fatigue of dovetail attachments.


2006 ◽  
Vol 28 (2) ◽  
pp. 83-93 ◽  
Author(s):  
Ngo Huong Nhu ◽  
Nguyen Truong Giang

This paper describes some results in analyzing cracked plates via FEM based on the procedures in CASTEM 2000 [1]. The basic methods for computing the crack parameters by the finite element analysis are presented. Some programs written by GIBIAN languages to solve problems for cracked plates are given. In possible cases, the numerical results are composed with analytical solution or testing result that gives a good agreement. The influence of plate configurations, the crack length, the external load type on the crack characteristic values are considered. The numerical analysis for inclined crack at angle and in arbitrary position of plate, the crack at hole in the plate, the crack of gravity dams are realized. The given results and programs can be applied to practical problems for controlling the brittle failure state of a structure.


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