scholarly journals Stress concentration in the vicinity of road сoating cracks

2021 ◽  
pp. 41-53
Author(s):  
Viktor Gaidaichuk ◽  
Liudmyla Shevchuk ◽  
Olena Bilobrytska ◽  
Serhii Baran
Keyword(s):  
Stress Concentration ◽  
Mechanical Behavior ◽  
Asphalt Concrete ◽  
Plastic Material ◽  
Multilayer Coating ◽  
Three Dimensional ◽  
Element Model ◽  
Operating Conditions ◽  
The Road ◽  
The Impact

The article presents the results of a computer analysis of the stress-strain state of a multilayer asphalt pavement under the influence of traffic loads. Based on the finite-element model of coating deformation, a study was made of the mechanical behavior of the system considered for various structural schemes for the existence of vertical cracks in various layers of the structure under the action of vertical transport loads. The effects of stress concentration in the system due to high-gradient deformation fields and structural imperfections of the multilayer coating were found. Multi-layer asphalt roads are one of the most common construction projects. Based on a review of the tasks of science about their strength and durability, these structures can be attributed to significantly complex types of building systems. This is primarily due to the multi-parameter nature of the factors that determine their design, material properties, types of loads and the impact on them, as well as their operating conditions. Therefore, designers of road structures and specialists who are involved in the theoretical modeling of the mechanical behavior of layered massifs during operation have to take into account many additional factors that complicate their work. These include the most important design and operational features of these systems, which significantly affect the nature of the distribution of stress and strain fields, as well as their intensity. First of all, they include special structural schemes of the road and pavement. It is a multilayer three-dimensional package having disproportionately different sizes along each direction. Hidden (as well as obvious) vertical cracks and horizontal delamination of the structure, sometimes permissible under operating conditions, can be added to the design model of a structure. Such violations of the continuity of the system also lead to discontinuity of the displacement functions, which further worsens the system’s performance and complicates the task of its modeling. The materials of the coating layers, which include asphalt concrete, cement, crushed stone, sand, soil, and others, also bring particular specificity to the work of the road structure. All of them differently resist tensile, compression and shear, and asphalt concrete is also elastic-viscous - plastic material, whose properties are largely dependent on temperature.

Investigation on Mechanical Properties of Fibreglass Reinforced Flexible Pipes Under Torsion

2018 ◽  
Author(s):  
Pan Fang ◽  
Yuxin Xu ◽  
Shuai Yuan ◽  
Yong Bai ◽  
Peng Cheng
Keyword(s):  
Mechanical Behavior ◽  
Torsion Angle ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Load Condition ◽  
Element Model ◽  
Flexible Pipe ◽  
Torsional Load ◽  
Flexible Pipes ◽  
The Impact

Fibreglass reinforced flexible pipe (FRFP) is regarded as a great alternative to many bonded flexible pipes in the field of oil or gas transportation in shallow water. This paper describes an analysis of the mechanical behavior of FRFP under torsion. The mechanical behavior of FRFP subjected to pure torsion was investigated by experimental, analytical and numerical methods. Firstly, this paper presents experimental studies of three 10-layer FRFP subjected to torsional load. Torque-torsion angle relations were recorded during this test. Then, a theoretical model based on three-dimensional (3D) anisotropic elasticity theory was proposed to study the mechanical behavior of FRFP. In addition, a finite element model (FEM) including reinforced layers and PE layers was used to simulate the torsional load condition in ABAQUS. Torque-torsion angle relations obtained from these three methods agree well with each other, which illustrates the accuracy and reliability of the analytical model and FEM. The impact of fibreglass winding angle, thickness of reinforced layers and radius-thickness ratio were also studied. Conclusions obtained from this research may be of great practicality to manufacturing engineers.

scholarly journals Driving Safety Analysis Using Grid-Based Water-Filled Rut Depth Distribution

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Jiao Yan ◽  
Hongwei Zhang ◽  
Bing Hui
Keyword(s):  
Water Depth ◽  
Three Dimensional ◽  
Element Model ◽  
Road Surface ◽  
Driving Safety ◽  
Vehicle Speed ◽  
Adhesion Coefficient ◽  
The Road ◽  
Left And Right ◽  
The Impact

The water accumulated in the rutted road sections poses a threat to the safety of vehicles. Water-filled ruts will cause partial or complete loss of the friction between tires and the road surface, leading to driving safety hazards such as hydroplaning and sliding. At present, the maximum water depth of left and right ruts is mostly adopted to analyze the safety of water-filled ruts, ignoring the uneven change of ruts in the driving direction and the cross-section direction, which cannot fully reflect the actual impact of asymmetric or uneven longitudinal ruts on the vehicle. In order to explore the impact of water-filled ruts on driving safety, a three-dimensional (3D) tire-road finite element model is established in this paper to calculate the adhesion coefficient between the tire and the road surface. Moreover, a model of the 3D water-filled rut-adhesion coefficient vehicle is established and simulated by the dynamics software CarSim. In addition, the influence of the water depth difference between the left and right ruts on the driving safety is quantitatively analyzed, and a safety prediction model for the water-filled rut is established. The results of the case study show that (1) the length of dangerous road sections based on vehicle skidding is longer than that based on hydroplaning, and the length of dangerous road sections based on hydroplaning is underestimated by 9.4%–100%; (2) as the vehicle speed drops from 120 km/h to 80 km/h, the length of dangerous road sections obtained based on vehicle sliding analysis is reduced by 93.8%. Therefore, in order to ensure driving safety, the speed limit is controlled within 80 km/h to ensure that the vehicle will not skid. The proposed method provides a good foundation for the vehicles to actively respond to the situation of the water-filled road section.

scholarly journals The effect of the outlet angle β2 on the thermomechanical behavior of a centrifugal compressor blade

2020 ◽  
Vol 29 (1) ◽  
pp. 1-8
Author(s):  
Ahmed Allali ◽  
Sadia Belbachir ◽  
Ahmed Alami ◽  
Belhadj Boucham ◽  
Abdelkader Lousdad
Keyword(s):  
Mechanical Behavior ◽  
Centrifugal Compressor ◽  
Three Dimensional ◽  
Complex Form ◽  
Compressor Blade ◽  
Stress Fields ◽  
The Finite Element Method ◽  
Mechanical Fatigue ◽  
Outlet Angle ◽  
The Impact

AbstractThe objective of this work lies in the three-dimensional study of the thermo mechanical behavior of a blade of a centrifugal compressor. Numerical modeling is performed on the computational code "ABAQUS" based on the finite element method. The aim is to study the impact of the change of types of blades, which are defined as a function of wheel output angle β2, on the stress fields and displacements coupled with the variation of the temperature.This coupling defines in a realistic way the thermo mechanical behavior of the blade where one can note the important concentrations of stresses and displacements in the different zones of its complex form as well as the effects at the edges. It will then be possible to prevent damage and cracks in the blades of the centrifugal compressor leading to its failure which can be caused by the thermal or mechanical fatigue of the material with which the wheel is manufactured.

Reduction of Free-Edge Stress Concentration

1985 ◽  
Vol 52 (4) ◽  
pp. 801-805 ◽  
Author(s):  
P. R. Heyliger ◽  
J. N. Reddy
Keyword(s):  
Finite Element ◽  
Stress Concentration ◽  
Finite Element Model ◽  
Three Dimensional ◽  
Element Model ◽  
Free Edge ◽  
Shear Stresses ◽  
Normal Stresses ◽  
Interlaminar Shear ◽  
Three Dimensional Elasticity

A quasi-three dimensional elasticity formulation and associated finite element model for the stress analysis of symmetric laminates with free-edge cap reinforcement are described. Numerical results are presented to show the effect of the reinforcement on the reduction of free-edge stresses. It is observed that the interlaminar normal stresses are reduced considerably more than the interlaminar shear stresses due to the free-edge reinforcement.

scholarly journals Multistage Impacts of the Heavy Rain Process on the Travel Speeds of Urban Roads

2021 ◽  
Vol 10 (8) ◽  
pp. 557
Author(s):  
Qiuping Li ◽  
Haowen Luo ◽  
Xuechen Luan
Keyword(s):  
Traffic Management ◽  
Urban Transportation ◽  
Three Dimensional ◽  
Heavy Rain ◽  
The Road ◽  
Road Surfaces ◽  
Speed Change ◽  
The Impact ◽  
The Relationship ◽  
Personal Travel

Heavy rain causes the highest drop in travel speeds compared with light and moderate rain because it can easily induce flooding on road surfaces, which can continue to hinder urban transportation even after the rainfall is over. However, very few studies have specialized in researching the multistage impacts of the heavy rain process on urban roads, and the cumulative effects of heavy rain in road networks are often overlooked. In this study, the heavy rain process is divided into three consecutive stages, i.e., prepeak, peak, and postpeak. The impact of heavy rain on a road is represented by a three-dimensional traffic speed change ratio vector. Then, the k-means clustering method is implemented to reveal the distinct patterns of speed change ratio vectors. Finally, the characteristics of the links in each cluster are analyzed. An empirical study of Shenzhen, China suggests that there are three major impact patterns in links. The differences among links associated with the three impact patterns are related to the road category, travel speeds in no rain days, and the number of transportation facilities. The findings in this research can contribute to a more in-depth understanding of the relationship between the heavy rain process and the travel speeds of urban roads and provide valuable information for traffic management and personal travel in heavy rain weather.

Comparison of Different Methods for Stress and Deflection Analysis in Embedded Die Packages during the Assembly Process

2014 ◽  
Vol 2014 (1) ◽  
pp. 000355-000360
Author(s):  
K. Macurova ◽  
R. Bermejo ◽  
M. Pletz ◽  
R. Schöngrundner ◽  
T. Antretter ◽  
...  
Keyword(s):  
Printed Circuit Board ◽  
Plastic Material ◽  
Three Dimensional ◽  
Diffraction Method ◽  
Element Model ◽  
Analytical Investigation ◽  
Circuit Board ◽  
Curvature Radius ◽  
Assembly Process ◽  
Deflection Analysis

Important topics for electronic packages are thermally induced stresses created during package manufacturing and their role in mechanical failure. In the present paper, an analytical and a numerical analysis of the assembly process (component attached with an adhesive to a copper foil) is investigated. This process is prior to the lamination of the printed circuit board. Stresses develop due to a mismatch of coefficients of thermal expansion and particularly to shrinkage associated with adhesive polymerization. The analytical investigation is based on the classical laminate theory and an interfacial model. The three-dimensional numerical finite element model is capable to use geometric and material properties which are not possible to investigate analytically. In particular, the influence of the adhesive meniscus and plastic material models for copper and adhesive are investigated. The models are validated experimentally by an X-ray diffraction method (Rocking-Curve-Technique) showing a good agreement of the calculated and measured curvature radius values.

Comparison of Different Methods for Stress and Deflection Analysis in Embedded Die Packages During the Assembly Process

2015 ◽  
Vol 12 (2) ◽  
pp. 80-85 ◽  
Author(s):  
K. Macurova ◽  
R. Bermejo ◽  
M. Pletz ◽  
R. Schöngrundner ◽  
T. Antretter ◽  
...  
Keyword(s):  
Printed Circuit Board ◽  
Plastic Material ◽  
Three Dimensional ◽  
Diffraction Method ◽  
Element Model ◽  
Analytical Investigation ◽  
Circuit Board ◽  
Curvature Radius ◽  
Assembly Process ◽  
Deflection Analysis

Important topics for electronic packages are thermally induced stresses created during package manufacturing and their role in mechanical failure. In the present paper, an analytical and a numerical analysis of the assembly process (component attached with an adhesive to a copper foil) is investigated. This process is prior to the lamination of the printed circuit board. Stresses develop due to a mismatch of coefficients of thermal expansion and particularly to shrinkage associated with adhesive polymerization. The analytical investigation is based on the classical laminate theory and an interfacial model. The three-dimensional, numerical, finite element model is capable of using geometric and material properties not possible to investigate analytically. In particular, the influence of the adhesive meniscus and plastic material models for copper and adhesive are investigated. The models are validated experimentally by an x-ray diffraction method (rocking-curve technique) showing a good agreement of the calculated and measured curvature radius values.

scholarly journals Focality of the Induced E-Field Is a Contributing Factor in the Choice of TMS Parameters: Evidence from a 3D Computational Model of the Human Brain

2020 ◽  
Vol 10 (12) ◽  
pp. 1010
Author(s):  
Deepika Konakanchi ◽  
Amy L. de Jongh Curry ◽  
Robert S. Waters ◽  
Shalini Narayana
Keyword(s):  
Spatial Distribution ◽  
Three Dimensional ◽  
Fem Simulation ◽  
Element Model ◽  
Brain Areas ◽  
Invasive Approach ◽  
Non Invasive ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element ◽  
The Impact

Transcranial magnetic stimulation (TMS) is a promising, non-invasive approach in the diagnosis and treatment of several neurological conditions. However, the specific results in the cortex of the magnitude and spatial distribution of the secondary electrical field (E-field) resulting from TMS at different stimulation sites/orientations and varied TMS parameters are not clearly understood. The objective of this study is to identify the impact of TMS stimulation site and coil orientation on the induced E-field, including spatial distribution and the volume of activation in the cortex across brain areas, and hence demonstrate the need for customized optimization, using a three-dimensional finite element model (FEM). A considerable difference was noted in E-field values and distribution at different brain areas. We observed that the volume of activated cortex varied from 3000 to 7000 mm3 between the selected nine clinically relevant coil locations. Coil orientation also changed the induced E-field by a maximum of 10%, and we noted the least optimal values at the standard coil orientation pointing to the nose. The volume of gray matter activated varied by 10% on average between stimulation sites in homologous brain areas in the two hemispheres of the brain. This FEM simulation model clearly demonstrates the importance of TMS parameters for optimal results in clinically relevant brain areas. The results show that TMS parameters cannot be interchangeably used between individuals, hemispheres, and brain areas. The focality of the TMS induced E-field along with its optimal magnitude should be considered as critical TMS parameters that should be individually optimized.

Fatigue Assessment of Dented Rigid Risers

2019 ◽  
Author(s):  
Elvis J. O. Santander ◽  
Bianca Pinheiro ◽  
Carlos Magluta ◽  
Ney Roitman
Keyword(s):  
Stress Concentration ◽  
Structural Integrity ◽  
Three Dimensional ◽  
Element Model ◽  
Oil Fields ◽  
Dimensional Finite Element ◽  
Concentration Factors ◽  
Stress Concentration Factors ◽  
Three Dimensional Finite Element ◽  
Remaining Fatigue Life

Abstract In the development of oil fields, submarine pipelines are used in various applications. These pipelines and risers are subject to accidents that may occur during operation, such as shocks between risers or shocks between a riser and an anchor, rock, or any equipment or heavy object, which may cause mechanical failure, such as dents. The objective of this work is to study of the effect of the introduction of plain dents on the structural integrity of rigid risers under fully reversed bending. A three dimensional finite element model was developed to estimate the stress concentration on dented risers under bending. Several numerical simulations were carried out to evaluate stress concentration factors (SCFs) for varying dimensions of dents and risers, in a parametric study. These SCFs can be used in the prediction of the remaining fatigue life of dented rigid risers.

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