scholarly journals Thermal Behavior of Cylindrical Buckling Restrained Braces at Elevated Temperatures

2014 ◽  
Vol 2014 ◽  
pp. 1-13 ◽  
Author(s):  
Elnaz Talebi ◽  
Mahmood Md. Tahir ◽  
Farshad Zahmatkesh ◽  
Airil Yasreen ◽  
Jahangir Mirza
Keyword(s):  
Elevated Temperatures ◽  
Three Dimensional ◽  
Circular Cross Section ◽  
Material Strength ◽  
Three Dimensional Model ◽  
Steel Core ◽  
Linear Behavior ◽  
Cylindrical Steel ◽  
Primary Focus ◽  
Brb System

The primary focus of this investigation was to analyze sequentially coupled nonlinear thermal stress, using a three-dimensional model. It was meant to shed light on the behavior of Buckling Restraint Brace (BRB) elements with circular cross section, at elevated temperature. Such bracing systems were comprised of a cylindrical steel core encased in a strong concrete-filled steel hollow casing. A debonding agent was rubbed on the core’s surface to avoid shear stress transition to the restraining system. The numerical model was verified by the analytical solutions developed by the other researchers. Performance of BRB system under seismic loading at ambient temperature has been well documented. However, its performance in case of fire has yet to be explored. This study showed that the failure of brace may be attributed to material strength reduction and high compressive forces, both due to temperature rise. Furthermore, limiting temperatures in the linear behavior of steel casing and concrete in BRB element for both numerical and analytical simulations were about 196°C and 225°C, respectively. Finally it is concluded that the performance of BRB at elevated temperatures was the same as that seen at room temperature; that is, the steel core yields prior to the restraining system.

A Model for Bending, Torsional, and Axial Vibrations of Micro- and Macro-Drills Including Actual Drill Geometry—Part I: Model Development and Numerical Solution

2010 ◽  
Vol 132 (4) ◽  
Author(s):  
Sinan Filiz ◽  
O. Burak Ozdoganlar
Keyword(s):  
Cross Section ◽  
Model Development ◽  
Three Dimensional ◽  
Circular Cross Section ◽  
Three Dimensional Model ◽  
Axial Thrust ◽  
One Dimensional ◽  
Three Dimensional Models ◽  
The Individual ◽  
Actual Geometry

Part I of this work presents a combined one-dimensional/three-dimensional approach for obtaining a unified model for the dynamics of micro- and macro-drills. To increase the numerical efficiency of the model, portions of the drill with circular cross-section (shank, extension, and tapered sections) are modeled using one-dimensional beam models without compromising model accuracy. A three-dimensional model is used for an accurate representation of the fluted section, considering the actual geometry with the pretwisted shape and axially varying (nonaxisymmetric) cross-section. The actual cross-section of the drills is incorporated to the model through a polynomial mapping while the pretwist effect is captured by defining a rotating reference frame. The boundary-value problem for both one- and three-dimensional models are derived using a variational approach, based on the extended Hamilton’s principle, and are subsequently solved by applying the spectral-Tchebychev technique. A component-mode synthesis is used for connecting the individual sections to obtain the dynamic model for the entire drill. Convergence of the model is studied by varying the number of polynomials for each section. The experimental validation of the model is included in Part II for both macro- and micro-drills. Also included in Part II is an analysis of drill dynamics for varying drill-geometry parameters and axial (thrust) force.

Numerical Investigation on Laser-Assisted Flow Forming Process

2014 ◽  
Vol 620 ◽  
pp. 29-34
Author(s):  
Ling Yan Sun ◽  
Chao Yang
Keyword(s):  
Laser Beam ◽  
Three Dimensional ◽  
Reduction Rate ◽  
Intense Laser ◽  
Material Strength ◽  
Three Dimensional Model ◽  
Forming Process ◽  
Flow Forming ◽  
Heating Source ◽  
Heating And Cooling

Recent years laser-assisted manufacturing techniques are increasingly the focus of the automotive and aerospace industry due to cost price, low energy efficiency and safety. Among these techniques is laser-assisted flow forming process that combines laser beam technology with conventional flow forming process. During forming the material undergoes a rapidly heating and cooling cycles with the irradiative action of the laser beam, which is quite different from the traditional process. A transient three-dimensional model was developed to investigate the influence of laser irradiation on the forming process, in which a user-defined function was created to overcome the problem of a moving Gaussian heating source. The result indicates that a ring-shaped temperature field is acquired when the heating source scans workpiece along a thread; the deformation area on the workpiece during forming is extensively and continuously heated by intense laser radiation and the thermally induced loss of material strength significantly increases the formability concerning the achievable material reduction rate and tool service life; the possibility of accuracy improvement by laser assistance has been investigated and an accuracy error decreases 10%-28.5%.

scholarly journals Deflections and Strains in Cracked Shafts Due to Rotating Loads: A Numerical and Experimental Analysis

2003 ◽  
Vol 9 (4) ◽  
pp. 303-311 ◽  
Author(s):  
Nicolò Bachschmid ◽  
Ezio Tanzi
Keyword(s):  
Three Dimensional ◽  
Circular Cross Section ◽  
Contact Forces ◽  
Dimensional Model ◽  
Axial Loads ◽  
Rotating Beam ◽  
Three Dimensional Model ◽  
System A ◽  
Bending Load ◽  
Rotating Load

In this article the deflections of a circular cross-section beam presenting a transverse crack of varying depths caused by various loads (bending, torsion, shear, and axial loads) are analyzed with the aid of a rather refined three-dimensional model that takes into account the nonlinear contact forces in the cracked area. The bending and shear loads are applied in several different angular positions in order to simulate a rotating load on a fixed beam or, by changing the reference system, a fixed load on a rotating beam. Torsion and axial loads are fixed with respect to the beam.Results obtained for the rotating beam can then be used for the analysis of cracked horizontal-axis heavy rotors in which the torsion is combined with the bending load. The effect of friction is also considered in the cracked area. The characteristic “breathing” behavior of the cracked area was analyzed and compared to that obtained with a rather simple one-dimensional model. The differences in results with respect to those based on fracture mechanics are emphasized. In order to highlight the effect of the presence of the crack, the deflections of the uncracked beam loaded with the same loads were subtracted from the deflections of the cracked beam.Finally, a cracked specimen was extensively analyzed by means of several strain gauges to study the strain distribution on the outer surface around the crack in various loading conditions. Consistent pre-stresses were found, and they influence the breathing behavior. The experimental results were compared with those obtained using the onedimensional linear model.

Stability Analysis on the Roof Trusses of the Broumov Group of Churches to Underline Statical Sense of Dientzenhofers

2010 ◽  
Vol 133-134 ◽  
pp. 385-390 ◽  
Author(s):  
Pavel Kuklík ◽  
Peter Duinker ◽  
Justin Hettinga
Keyword(s):  
18Th Century ◽  
Three Dimensional ◽  
Order Theory ◽  
Material Strength ◽  
Three Dimensional Model ◽  
Finite Element Software ◽  
Structural Capacity ◽  
Identification Of Fungi ◽  
Three Dimensional Models ◽  
The Stability

The Broumov group of churches represents an integral part of Bohemian baroque architecture. The famous Dientzenhofer family of architects, that helped define the Bohemian baroque style in the early 18th century, designed the Broumov group for the governing Benedictine abbey of St. Wenceslaw in Broumov. This report summarizes a structural investigation, using FIN10 finite element software, into the stability and efficiency of the roof trusses design. The structures age and current state were taken into account in calculating both the applied loads and structural capacity by increasing loads and reducing material strength. A damage analysis, including identification of fungi species, was performed, documented and implemented in a three-dimensional model for comparison with undamaged results. Magnitude and distribution of axial and bending forces were determined using both two dimensional and three-dimensional models for several load cases. Using the comparison of 1st order and 2nd order structural analysis results and Eurocode specified criteria, critical and unnecessary members of the roof system were identified and evaluated. Classical linear elastic 2nd order theory was used based of Eulerian principles, ignoring geometrical non-linearity and non-linear material effects. The main analysis was performed on the St. Ann church in Viznov and St. Barbora church in Otovice.

Research of Special-Shaped Membrane Electrode Assembly for Direct Methanol Fuel Cell

2011 ◽  
Vol 464 ◽  
pp. 409-413 ◽  
Author(s):  
Xing Xing Wang ◽  
Hong Jun Ni ◽  
Yu Zhu ◽  
Ming Yu Huang ◽  
Ping Liao
Keyword(s):  
Cross Section ◽  
Three Dimensional ◽  
Circular Cross Section ◽  
Catalyst Layer ◽  
Membrane Electrode Assembly ◽  
Gas Diffusion ◽  
Cathode Layer ◽  
Membrane Electrode ◽  
Titanium Mesh ◽  
Three Dimensional Model

In order to reduce the costs, improve the performances and promote the industry process, basing on calculus and finite element thinking, conceptual design of special-shaped membrane electrode assembly (S-MEA) was proposed, including six shapes. S-MEA size was determined by calculating, admeasuring and devising elaborately, whose basic parameter was gained from experiment datum. S-MEA was made up of titanium mesh anode layer, anode catalyst layer, Nafion membrane layer, cathode catalyst layer, gas diffusion layer and titanium mesh cathode layer in turn, which was different from MEA of the fluid field bipolar plates in the macro-structure but had the same micro-mechanism. Three-dimensional model was devised through Pro/E, planar diagrammatic drawing was created by the software also, and detail drawing was designed further with CAD. The process of preparing S-MEA was researched basing on the design. Then three typical S-MEA prototypes were made by bend-hot-pressing with home-made molds and precision hydraulic machine, including open triangular cross-section MEA, circular cross-section MEA and square cross-section MEA.

Three-Dimensional Model for Virtual Surgical Simulation, during Complex Skull Base Surgery and Aneurysm Surgery

Skull Base ◽  
2008 ◽  
Vol 18 (S 01) ◽  
Author(s):  
Akio Morita ◽  
Toshikazu Kimura ◽  
Shigeo Sora ◽  
Kengo Nishimura ◽  
Hisayuki Sugiyama ◽  
...  
Keyword(s):  
Skull Base ◽  
Surgical Simulation ◽  
Skull Base Surgery ◽  
Three Dimensional ◽  
Aneurysm Surgery ◽  
Dimensional Model ◽  
Three Dimensional Model

Digitalization system of ancient architecture decoration art based on neural network and image features

2020 ◽  
pp. 1-12
Author(s):  
Wu Xin ◽  
Qiu Daping
Keyword(s):  
Neural Network ◽  
Construction Industry ◽  
Three Dimensional ◽  
Performance Testing ◽  
Image Features ◽  
Three Dimensional Model ◽  
Performance Effect ◽  
Data Process ◽  
And Performance ◽  
Construction Mode

The inheritance and innovation of ancient architecture decoration art is an important way for the development of the construction industry. The data process of traditional ancient architecture decoration art is relatively backward, which leads to the obvious distortion of the digitalization of ancient architecture decoration art. In order to improve the digital effect of ancient architecture decoration art, based on neural network, this paper combines the image features to construct a neural network-based ancient architecture decoration art data system model, and graphically expresses the static construction mode and dynamic construction process of the architecture group. Based on this, three-dimensional model reconstruction and scene simulation experiments of architecture groups are realized. In order to verify the performance effect of the system proposed in this paper, it is verified through simulation and performance testing, and data visualization is performed through statistical methods. The result of the study shows that the digitalization effect of the ancient architecture decoration art proposed in this paper is good.

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