Finite Element Stability Analysis of a Glulam Dome

1992 ◽  
Vol 7 (4) ◽  
pp. 353-361 ◽  
Author(s):  
S.M. Holzer ◽  
C.H. Wu ◽  
J. Tissaoui
Keyword(s):  
Finite Element ◽  
Joint Stiffness ◽  
Buckling Load ◽  
Nonlinear Method ◽  
Beam Elements ◽  
Eigenvalue Method ◽  
Straight Beam ◽  
Glued Laminated Timber ◽  
The Status ◽  
The Stability

The paper centres on stability investigations of a glued-laminated timber (glulam) dome under several snow load conditions. The dome consists of a triangulated network of curved glulam beams, a decking supported by curved purlins, and a steel tension ring. The dome is represented by two different models. The first model is a rigid-jointed space frame composed of curved beam elements. The second model consists of straight beam elements, with rigid or flexible joints, and a bracing to simulate the lateral support of the beams provided by the decking. Two finite element methods are presented and used in the analyses: A nonlinear method that computes the buckling load and a combined nonlinear/linear eigenvalue method that provides estimates of the buckling load. The results presented include buckling pressures, buckling modes, effects of joint stiffness and bracing on the stability of the dome, and the status of the material prior to buckling.

Semi-Rigid Connection in Timber Structure: Stiffness Reduction and Instability Interaction

2020 ◽  
Vol 20 (07) ◽  
pp. 2050072 ◽  
Author(s):  
A. Manuello
Keyword(s):  
Joint Stiffness ◽  
Structural Response ◽  
Actual Condition ◽  
Space Structures ◽  
Beam Elements ◽  
Stiffness Reduction ◽  
Rigid Connection ◽  
Geometrical Imperfections ◽  
The Stability ◽  
Rigid Joints

Latticed shells and domes usually consist of hundreds, sometimes thousands, beam elements connected by rigid or semi-rigid joints. These connecting elements result, generally, very sophisticated, made with different materials and constituted by disparate connection systems. Recently, the stiffness connections were studied, numerically and experimentally, as one of the most important factors influencing significantly the structural response of space structures and domes. Very often, in the design process, the joints are assumed to be hinged or clamped. This assumption may result significantly far from the actual condition of in-service structure and components, leading to not understanding or not being able to prevent sudden catastrophic collapses (buckling, snap-through). Thus, the inclusion of joint stiffness reduction in the numerical model is necessary, more and more also due to the types of external loads, such as overloads that occur during the life of the structure or, especially, seismic solicitations. In this paper, the stability of an existent timber dome has been studied increasing the yieldingness of the connecting nodes according to an original approach. In addition, sensitivity of this kind of structure to the amplitude and the geometrical imperfections shape have been also considered. Numerical analyses have been conducted with local displacement controls, to take into account the geometric nonlinearity effects. Results evidenced that the dome is affected by instability interaction for particular slenderness and stiffness reduction of the connections.

Finite Element Method for Solving Bucking Load of Semi-Rigid Steel Frame

2013 ◽  
Vol 834-836 ◽  
pp. 1337-1342
Author(s):  
Hua Hu Cheng ◽  
Ai Min Li ◽  
Ming Wen Guan ◽  
Xian Wei Yang ◽  
Jing Luo
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Stiffness Matrix ◽  
Internal Force ◽  
Steel Frame ◽  
Buckling Load ◽  
Stability Characteristic ◽  
The Stability ◽  
Global Stiffness Matrix ◽  
Element Method

Took two layers of single span lateral sway semi-rigid connecting steel frame to bear vertical load function as the research object, adopting finite element method for solving the bucking load of the whole losing the stability of the semi-rigid connecting steel frame. Using based on the energy method and the three parabolic interpolation deflection curve function to obtain the relationship between the both element ends of internal force and displacement and introducing semi-rigid beam element stiffness matrix and geometric stiffness matrix of element integrate the global stiffness matrix which contains the flexibility of the connections and the component geometry nonlinear, thus deducing the stability characteristic equation of semi-rigid steel frame. And the MATLAB language composition program is applied to calculate the buckling load of overall losing stability of the semi-rigid steel frame, thus obtaining the buckling load of semi-rigid steel frame. The method is a very effective numerical calculating method which can solve the stability problems of relatively complicated stress conditions or relatively complicated structure composition conditions and it can also satisfy the requirement of higher calculation accuracy, easy for programming and calculation and of great practicability.

On the Finite Element Modelling and Simulation of Carbon Nanotubes

2014 ◽  
Vol 607 ◽  
pp. 55-61 ◽  
Author(s):  
Ghasem Ghadyani ◽  
Mojtaba Akbarzade ◽  
Andreas Öchsner
Keyword(s):  
Carbon Nanotubes ◽  
Finite Element ◽  
Beam Theory ◽  
Elastic Stiffness ◽  
Buckling Load ◽  
Timoshenko Beams ◽  
Bernoulli Beam ◽  
Critical Buckling Load ◽  
Beam Elements ◽  
Mesh Density

In this paper, two different beam elements (i.e. according to the Bernoulli beam and Timoshenko beam theory) for the modeling of the behavior of carbon nanotubes are applied. Finite element models are developed for this study with variation of chirality for both zig-zag and armchair configurations of CNTs. The deformations from the finite element simulations are subsequently used to predict the elastic stiffness and the critical buckling load in terms of material and geometric parameters. Furthermore, the dependence of mechanical properties on the kind of beam element and the mesh density is also compared. Based on the obtained results, Youngs modulus and critical buckling load of structures using Timoshenko beams are clearly lower than the Bernoulli beam approach for all chiralities.

Investigation on the Effect of Resin Content on Buckling of Laminated Composite Plates

2014 ◽  
Vol 1035 ◽  
pp. 212-218
Author(s):  
Qi You Cheng ◽  
Jian Ping Huang ◽  
Ai Min Ling ◽  
Zhi Zhuang Feng
Keyword(s):  
Finite Element ◽  
Elastic Modulus ◽  
Failure Modes ◽  
Volume Fraction ◽  
Laminated Composite ◽  
Composite Plates ◽  
Buckling Load ◽  
Laminated Composite Plates ◽  
Element Analysis ◽  
The Stability

Aerospace applications of composites involve components that are relatively thin plate or shell like structures, thus requiring the consideration of buckling as one of the many possible failure modes. To study the effect of the resin volume fraction on stability of composites, a finite element method based on micromechanics and classical lamination theory has been established to compute buckling loads of simply supported symmetric laminated composite plates subjected to the load of in-plane axial compress and shear load, respectively. The analysis procedure includes a Micromechanical finite element analysis that predicts the elastic modulus of lamina and a finite element linear buckling analysis that predicts buckling load of the composite plates. Three kinds of resin volume fraction that are equal to 44 percent, 47 percent, and 50 percent respectively are considered. The results show that the resin volume fraction has obvious influence on the stability of composite plate. The plate exhibits a relatively large increase in buckling load, about 12 percent, when the resin volume fraction increases by 3 percent. It is finds that the bending stiffness that has an obvious influence on the stability is an incremental function of elastic modulus and cubic thickness. The elastic modulus will be decreased slightly with the increase of resin volume fraction. However, the thickness of the plates is proportional to resin volume fraction.

Identification of the Dynamic Properties of Linear Joints Using Substructure Synthesis Method

2010 ◽  
Vol 44-47 ◽  
pp. 712-718
Author(s):  
Ling Li ◽  
Li Gang Cai ◽  
Tie Neng Guo ◽  
Zhi Feng Liu
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Dynamic Properties ◽  
Synthesis Method ◽  
Joint Stiffness ◽  
Element Model ◽  
Substructure Synthesis ◽  
The Stability ◽  
Stiffness And Damping ◽  
Good Agreement

In this thesis, a new identification method for joint stiffness and damping has been developed by using the substructure synthesis method and finite element modeling. The substructure synthesis method is stated firstly, according to the substructures are connected by joints and the equilibrium and compatibility conditions at the joints have to be fulfilled, establishing identification equation through completely frequency response function. Then, finite element model is established, and update this model, make use of the update model to replace the experimental model, using an accurate finite element model to obtain the required data. In order to ensure the stability of the numerical calculation, translate inconsistent equation into the general solution through the principle of least squares, besides the introduction of the concept of weighted, makes the measured data can be fully utilized. Finally, the method is applied to a simulated example and good agreement is found between identified and true parameters.

Migration imaginations of residents of the Khabarovsk territory: experience of the pilot sociological research

2020 ◽  
Vol 93 (4) ◽  
pp. 215-226
Author(s):  
V. V. Zubkov ◽  
◽  
P.G. Sidorov ◽  
Keyword(s):  
Research Methodology ◽  
Sociological Research ◽  
Sociological Study ◽  
Target Groups ◽  
Permanent Residence ◽  
Sociological Approach ◽  
The Status ◽  
Personal Attitudes ◽  
The Stability

The article presents the results of a pilot sociological study of migration perceptions of the population, the reasons for their formation, as well as the factors and conditions under which the willingness to live and work in the Khabarovsk Territory is realized. The analysis of the results of the survey, which according to the research methodology was conducted in two target groups ("residents of the region" and "student youth"), indicates the stability and reproduction of migration intentions as a determined willingness and desire to leave the place of permanent residence in the Khabarovsk territory. The sociological approach to the study of migration perceptions of the target groups under study consists in determining the target attitudes, guidelines and expectations from moving, due to the status-role set and personal attitudes of respondents.

Buckling characteristics of cut-out borne composite stiffened hyperbolic paraboloid shell panel

2021 ◽  
pp. 146442072110058
Author(s):  
Sarmila Sahoo
Keyword(s):  
Finite Element ◽  
Orientation Angle ◽  
Buckling Load ◽  
Benchmark Problems ◽  
Hyperbolic Paraboloid ◽  
Element Analysis ◽  
Load Effect ◽  
Global Buckling ◽  
Fiber Orientation Angle ◽  
Shell Panel

The present study investigates buckling characteristics of cut-out borne stiffened hyperbolic paraboloid shell panel made of laminated composites using finite element analysis to evaluate the governing differential equations of global buckling of the structure. The finite element code is validated by solving benchmark problems from literature. Different parametric variations are studied to find the optimum panel buckling load. Laminations, boundary conditions, depth of stiffener and arrangement of stiffeners are found to influence the panel buckling load. Effect of different parameters like cut-out size, shell width to thickness ratio, degree of orthotropy and fiber orientation angle of the composite layers on buckling load are also studied. Parametric and comparative studies are conducted to analyze the buckling strength of composite hyperbolic paraboloid shell panel with cut-out.

scholarly journals Inlay-Retained Dental Bridges—A Finite Element Analysis

2021 ◽  
Vol 11 (9) ◽  
pp. 3770
Author(s):  
Monica Tatarciuc ◽  
George Alexandru Maftei ◽  
Anca Vitalariu ◽  
Ionut Luchian ◽  
Ioana Martu ◽  
...  
Keyword(s):  
Finite Element ◽  
Young Patients ◽  
Maximum Pressure ◽  
Class Iii ◽  
Element Analysis ◽  
Dental Prostheses ◽  
Abutment Teeth ◽  
Fixed Dental Prostheses ◽  
Implant Therapy ◽  
The Stability

Inlay-retained dental bridges can be a viable minimally invasive alternative when patients reject the idea of implant therapy or conventional retained full-coverage fixed dental prostheses, which require more tooth preparation. Inlay-retained dental bridges are indicated in patients with good oral hygiene, low susceptibility to caries, and a minimum coronal tooth height of 5 mm. The present study aims to evaluate, through the finite element method (FEM), the stability of these types of dental bridges and the stresses on the supporting teeth, under the action of masticatory forces. The analysis revealed the distribution of the load on the bridge elements and on the retainers, highlighting the areas of maximum pressure. The results of our study demonstrate that the stress determined by the loading force cannot cause damage to the prosthetic device or to abutment teeth. Thus, it can be considered an optimal economical solution for treating class III Kennedy edentation in young patients or as a provisional pre-implant rehabilitation option. However, special attention must be paid to its design, especially in the connection area between the bridge elements, because the connectors and the retainers represent the weakest parts.

scholarly journals Modelling and Stability Analysis of Articulated Vehicles

2021 ◽  
Vol 11 (8) ◽  
pp. 3663
Author(s):  
Tianlong Lei ◽  
Jixin Wang ◽  
Zongwei Yao
Keyword(s):  
Stability Analysis ◽  
Critical Velocity ◽  
Equations Of State ◽  
Steering System ◽  
Analysis Model ◽  
Nonlinear Dynamic Model ◽  
Equilibrium Equations ◽  
Eigenvalue Method ◽  
Articulated Vehicles ◽  
The Stability

This study constructs a nonlinear dynamic model of articulated vehicles and a model of hydraulic steering system. The equations of state required for nonlinear vehicle dynamics models, stability analysis models, and corresponding eigenvalue analysis are obtained by constructing Newtonian mechanical equilibrium equations. The objective and subjective causes of the snake oscillation and relevant indicators for evaluating snake instability are analysed using several vehicle state parameters. The influencing factors of vehicle stability and specific action mechanism of the corresponding factors are analysed by combining the eigenvalue method with multiple vehicle state parameters. The centre of mass position and hydraulic system have a more substantial influence on the stability of vehicles than the other parameters. Vehicles can be in a complex state of snaking and deviating. Different eigenvalues have varying effects on different forms of instability. The critical velocity of the linear stability analysis model obtained through the eigenvalue method is relatively lower than the critical velocity of the nonlinear model.

scholarly journals Determinants of judges’ career choices and productivity: a Polish case study

2021 ◽  
Author(s):  
Przemysław Banasik ◽  
Katarzyna Metelska-Szaniawska ◽  
Małgorzata Godlewska ◽  
Sylwia Morawska
Keyword(s):  
Career Choices ◽  
Social Recognition ◽  
District Courts ◽  
Self Monitoring ◽  
Administrative Supervision ◽  
Judicial Efficiency ◽  
The Status ◽  
Service Mission ◽  
The Stability

AbstractThe goal of this paper is to identify factors which affect judges’ productivity and career choice motives with the view of increasing judicial efficiency. Specifically, the investigation focuses on such aspects as judges’ remuneration, promotion, threat of judgment revocation, service/mission, periodic assessment, the threat of a complaint about protracted proceedings or of disciplinary proceedings, the threat of destabilization of the employment relationship, status/prestige of the profession, power/authority, social recognition, leisure, as well as administrative supervision and self-monitoring. To this end, a survey was conducted among judges of three of the largest Polish regional courts and subordinate district courts. The descriptive and statistical analyses show that judges’ care for the number of cases resolved, proxying for their productivity, is significantly correlated with self-monitoring of their adjudication activity. The stability of employment, the status/prestige of the profession and a relatively high remuneration are the most important factors in terms of judges’ career choices. In their care for the number of cases resolved remuneration is, albeit, no longer a relevant factor. Judges monitor their productivity due to reasons other than remuneration, possibly the sense of service/mission and the threat of various adverse consequences, the evidence for which is, however, also rather weak.

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