A new methodological approach to assess the stability of discontinuous rocky cliffs using in-situ surveys supported by UAV-based techniques and 3-D finite element model: a case study

2019 ◽  
Vol 260 ◽  
pp. 105205 ◽  
Author(s):  
N.L. Fazio ◽  
M. Perrotti ◽  
G.F. Andriani ◽  
F. Mancini ◽  
P. Rossi ◽  
...  
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Methodological Approach ◽  
Element Model ◽  
The Stability

Finite Element Analysis of Flexible Pipes Under Compression: Influence of the Sample Length

2015 ◽  
Author(s):  
Eduardo Ribeiro Malta ◽  
Clóvis de Arruda Martins
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
High Strength ◽  
Element Model ◽  
Sample Length ◽  
Flexible Pipe ◽  
Element Analysis ◽  
Flexible Pipes ◽  
The Stability

In order to study the compressive behavior of flexible pipes, a nonlinear tridimensional finite element model was developed. This model recreates a five layer flexible pipe with two tensile armor layers, an external polymeric sheath, an orthotropic high strength tape and a rigid inner nucleus. Using this model, several studies are being conducted to verify the influence of key parameters on the wire instability phenomenon. The pipe sample length can be considered one of these parameters and its variation causes significant change at the stability response of the tensile layers. This article includes a detailed description of the finite element model itself and a case study where the length of the pipe is changed. The procedure of this analysis is here described, along with the results.

scholarly journals Modeling inflatable fabric with undevelopable surfaces by motion folding method

2019 ◽  
Vol 14 ◽  
pp. 155892501988640
Author(s):  
Xiao-Shun Zhao ◽  
He Jia ◽  
Zhihong Sun ◽  
Li Yu
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Numerical Study ◽  
Technical Problem ◽  
Three Dimensional ◽  
Element Model ◽  
Model Errors ◽  
Folding Model ◽  
Study Results ◽  
The Stability

At present, most space inflatable structures are composed of flexible inflatable fabrics with complex undevelopable surfaces. It is difficult to establish a multi-dimensional folding model for this type of structure. To solve this key technical problem, the motion folding method is proposed in this study. First, a finite element model with an original three-dimensional surface was flattened with a fluid structure interaction algorithm. Second, the flattened surface was folded based on the prescribed motion of the node groups, and the final folding model was obtained. The fold modeling process of this methodology was consistent with the actual folding processes. Because the mapping relationship between the original finite element model and the final folding model was unchanged, the initial stress was used to modify the model errors during folding process of motion folding method. The folding model of an inflatable aerodynamic decelerator, which could not be established using existing folding methods, was established by using motion folding method. The folding model of the inflatable aerodynamic decelerator showed that the motion folding method could achieve multi-dimensional folding and a high spatial compression rate. The stability and regularity of the inflatable aerodynamic decelerator numerical inflation process and the consistency of the inflated and design shapes indicated the reliability, applicability, and feasibility of the motion folding method. The study results could provide a reference for modeling complex inflatable fabrics and promote the numerical study of inflatable fabrics.

Finite Element Analysis of Flexible Pipes Under Axial Compression: Influence of the Sample Length

2016 ◽  
Vol 139 (1) ◽  
Author(s):  
Eduardo Ribeiro Malta ◽  
Clóvis de Arruda Martins
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Inner Core ◽  
High Sensitivity ◽  
Element Model ◽  
Sample Length ◽  
Flexible Pipe ◽  
Element Analysis ◽  
Flexible Pipes

In order to study the axial compressive behavior of flexible pipes, a nonlinear tridimensional finite element model was developed. This model recreates a five layer flexible pipe with two tensile armor layers, an external polymeric sheath, an orthotropic high strength tape, and a rigid inner core. Using this model, several studies were conducted to verify the influence of key parameters on the wire instability phenomenon. The pipe sample length can be considered as one of these parameters. This paper includes a detailed description of the finite element model itself and a case study where the length of the pipe is varied. The procedure of this analysis is here described and a case study is presented which shows that the sample length itself has no practical effect on the prebuckling response of the samples and a small effect on the limit force value. The postbuckling response, however, presented high sensitivity to the changes, but its erratic behavior has made impossible to establish a pattern.

Static and Dynamic Finite Element Model Updating of a Rigid Frame-Continuous Girders Bridge Based on Response Surface Method

2013 ◽  
Vol 639-640 ◽  
pp. 992-997 ◽  
Author(s):  
Jian Ping Han ◽  
Yong Peng Luo
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Response Surface ◽  
Test Data ◽  
Dynamic Test ◽  
Element Model ◽  
Surface Method ◽  
Rigid Frame ◽  
The Finite Element Model

Using the static and dynamic test data simultaneously to update the finite element model can increase the available information for updating. It can overcome the disadvantages of updating based on static or dynamic test data only. In this paper, the response surface method is adopted to update the finite element model of the structure based on the static and dynamic test. Using the reasonable experiment design and regression techniques, a response surface model is formulated to approximate the relationships between the parameters and response values instead of the initial finite element model for further updating. First, a numerical example of a reinforced concrete simply supported beam is used to demonstrate the feasibility of this approach. Then, this approach is applied to update the finite element model of a prestressed reinforced concrete rigid frame-continuous girders bridge based on in-situ static and dynamic test data. Results show that this approach works well and achieve reasonable physical explanations for the updated parameters. The results from the updated model are in good agreement with the results from the in-situ measurement. The updated finite element model can accurately represent mechanical properties of the bridge and it can serve as a benchmark model for further damage detection and condition assessment of the bridge.

Tribological Process Characterization With In-Situ Quantitative Nano-Scale Metrology

2005 ◽  
Author(s):  
Antanas Daugela ◽  
Alex Meyman ◽  
Vladimir Knyazik ◽  
Nikolai Yeremin
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Finite Element Model ◽  
Element Model ◽  
Optical Microscope ◽  
Nano Scale ◽  
Process Characterization ◽  
Microscope Imaging

A novel quantitative nano+micro-tribometer with integrated nanoindenter, SPM and optical microscope imaging has been used to characterize mechanical properties of Cu coated Si wafers at various test stages. A 2D Finite Element Model was developed to study changes on workhardened contacts assessed via nanoindentation experiments.

Analysis of the Stability of Thawing Slopes by Random Finite Element Method

2019 ◽  
Vol 2673 (10) ◽  
pp. 465-476 ◽  
Author(s):  
Shaoyang Dong ◽  
Xiong (Bill) Yu
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Factor Of Safety ◽  
Limit Equilibrium ◽  
Element Model ◽  
Frozen Soil ◽  
Silty Clay ◽  
Local Factor ◽  
The Stability ◽  
Random Finite Element

A significant number of landslides occur in cold regions because of freezing and thawing cycles. The instability of thawing slopes can cause serious damage to transportation infrastructure and property, and even loss of human life. This type of landslide is difficult to analyze by the traditional limit-equilibrium methods, however, because of the complicated multi-physics processes involved. This paper describes a holistic microstructure-based random finite element model (RFEM) to simulate the stability of a thawing slope. The RFEM model is developed to simulate the bulk behaviors of frozen and unfrozen soils based on the behaviors of individual phases. The phase coded image of a frozen silty clay is first custom built and then converted into a finite element model. The mechanical behaviors of individual phases of the frozen soil are calibrated by uniaxial compressive test. The triaxial test is then simulated by RFEM to obtain the shear strength parameters of frozen and unfrozen soils. Coupled thermal-mechanical REFM models are developed to simulate the effects of temperature on the displacement field and stress field in the slope. From the results, the local factor of safety field can be determined. The development of local factor of safety and potential failure surface associated with the thawing process over a typical year are simulated by this new model. The variations in the stability of thawing slopes predicted by this model are consistent with field observations as well as the global-wise slope stability analysis.

scholarly journals Vibration Control of an Unbalanced Single-Side Cantilevered Rotor System with a Novel Integral Squeeze Film Bearing Damper

2019 ◽  
Vol 9 (20) ◽  
pp. 4371 ◽  
Author(s):  
Yipeng Zhang ◽  
Lidong He ◽  
Jianjiang Yang ◽  
Fangteng Wan ◽  
Jinji Gao
Keyword(s):  
Finite Element ◽  
Energy Distribution ◽  
Finite Element Model ◽  
Vibration Control ◽  
Element Model ◽  
Rotor System ◽  
Squeeze Film ◽  
Single Side ◽  
The Stability ◽  
Stability Energy

In this paper, vibration control of an unbalanced single-side cantilevered rotor system using a novel integral squeeze film bearing damper in terms of stability, energy distribution, and vibration control is analyzed. A finite element model of such a system with an integral squeeze film bearing damper (ISFBD) is developed. The stability, energy distribution, and vibration control of the unbalanced single-side cantilevered rotor system are calculated and analyzed based on the finite element model. The stiffness of the integral squeeze film bearing damper is designed using theoretical calculation and finite element model (FEM) simulation. The influence of installation position and quantity of integral squeeze film bearing dampers on the vibration control of the unbalanced cantilevered rotor system is discussed. An experimental platform is developed to validate the vibration control effect. The results show that the installation position and quantity of the integral squeeze film bearing dampers have different effects on the stability, energy distribution, and vibration control of the unbalanced cantilevered rotor system. When ISFBDs are installed at both bearing housings, the vibration control is best, and the vibration components of the time and frequency domains have good vibration control effects in four working conditions.

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