scholarly journals Influence of Modulus of Base Layer on The Strain Distribution for Asphalt Pavement

2021 ◽  
Vol 16 (4) ◽  
pp. 126-152
Author(s):  
Kang Yao ◽  
Xin Jiang ◽  
Jin Jiang ◽  
Zhonghao Yang ◽  
Yanjun Qiu
Keyword(s):  
Strain Distribution ◽  
Tensile Strain ◽  
Asphalt Pavement ◽  
Compressive Strain ◽  
Three Dimensional ◽  
Vertical Direction ◽  
Element Model ◽  
Neutral Axis ◽  
Base Layer ◽  
Maximum Tensile Strain

In order to investigate the influence of modulus of the base layer on the strain distribution for asphalt pavement, the modulus ratio of the base layer and the AC layer (Rm) is introduced as a controlled variable when keeping modulus of the AC layer as a constant in this paper. Then, a three-layered pavement structure is selected as an analytical model, which consists of an AC layer with the constant modulus and a base layer with the variable modulus covering the subgrade. A three dimensional (3D) finite element model was established to estimate the strains along the horizontal and vertical direction in the AC layer under different Rm. The results show that Rm will change the distribution of the horizontal strains along the depth in the AC layer; the increase of Rm could reduce the maximum tensile strain in the AC layer, but its effect is limited; the maximum tensile strain in the AC layer does not necessarily occur at the bottom, but gradually rises to the middle with the increase of Rm. Rm could significantly decline the bottom strain in the AC layer, and there is a certain difference between the bottom and the maximum strain when Rm is greater than or equal to one, which will enlarge with increasing Rm. Rm could change the depth of the neutral axis in the AC layer, and the second neutral axis will appear at the bottom of the AC layer under a sufficiently large Rm. The average vertical compressive strain in the AC layer will significantly enlarge with the increase of Rm.

Using the Asphalt Pavement Layer Condition Assessment Program: Case Studies

2003 ◽  
Vol 1860 (1) ◽  
pp. 66-75 ◽  
Author(s):  
Bing Xu ◽  
S. Ranji Ranjithan ◽  
Y. Richard Kim
Keyword(s):  
Case Studies ◽  
Asphalt Pavement ◽  
Compressive Strain ◽  
Dynamic Effect ◽  
Field Measurements ◽  
Condition Assessment ◽  
Base Layer ◽  
Element Analysis ◽  
Condition Indicators ◽  
Assessment Program

The Asphalt Pavement Layer Condition Assessment Program (APLCAP) is developed in this research to help highway agencies assess layer conditions of asphalt pavements. APLCAP implements a new integrated procedure for condition assessment from falling-weight deflectometer (FWD) deflections. The main components of this procedure include screening of FWD raw deflections, predictions of condition indicators from FWD measurements, structural adjustments for the predicted condition indicators, and layer condition evaluation based on the adjusted condition indicators. This procedure was developed on the basis of dynamic nonlinear finite element analysis and calibrated using field measurements. The three case studies presented show that the APLCAP algorithms can predict the asphalt concrete modulus, pavement critical strains, and strengths of the base and subgrade quite well, but not the compressive strain in the aggregate base layer. Although the APLCAP procedure includes the complicated dynamic effect of FWD loading and nonlinear behavior of unbound materials, the time to obtain results from this procedure is insignificant and therefore suitable for real-time evaluation of pavement conditions.

Stress Analysis of the Polyethylene Component in Total Ankle Arthroplasty: Effect of Thickness

2003 ◽  
Author(s):  
Karol Galik ◽  
Patrick Smolinski ◽  
Stephen F. Conti ◽  
Mark C. Miller
Keyword(s):  
Contact Pressure ◽  
Sagittal Plane ◽  
Distal Tibia ◽  
Three Dimensional ◽  
Vertical Direction ◽  
Element Model ◽  
Polyethylene Liner ◽  
Minimal Thickness ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

A three-dimensional finite element model was constructed of the distal tibia and fibula and a semi-constrained ankle prosthesis (Agility™ system). Contact elements were used at the interface between the talar component and the polyethylene liner and the proximal tibia and fibular were loaded in the in vertical direction. The minimal thickness of the polyethylene liner was varied from 3 mm to 8 mm in 1 mm increments. The results showed that the liner contact pressure in the sagittal plane mid-line decreased from 20 MPa to 14 MPa with increasing thickness while the medial edge contact pressure increased from 26 MPa to 30 MPa.

scholarly journals Enhanced Stretchable and Sensitive Strain Sensor via Controlled Strain Distribution

Nanomaterials ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 218 ◽  
Author(s):  
Huamin Chen ◽  
Longfeng Lv ◽  
Jiushuang Zhang ◽  
Shaochun Zhang ◽  
Pengjun Xu ◽  
...  
Keyword(s):  
Strain Distribution ◽  
Tensile Strain ◽  
Strain Sensor ◽  
Gauge Factor ◽  
Simple Method ◽  
Practical Applications ◽  
Simple Strategy ◽  
Highly Sensitive ◽  
Highly Stretchable ◽  
Maximum Tensile Strain

Stretchable and wearable opto-electronics have attracted worldwide attention due to their broad prospects in health monitoring and epidermal applications. Resistive strain sensors, as one of the most typical and important device, have been the subject of great improvements in sensitivity and stretchability. Nevertheless, it is hard to take both sensitivity and stretchability into consideration for practical applications. Herein, we demonstrated a simple strategy to construct a highly sensitive and stretchable graphene-based strain sensor. According to the strain distribution in the simulation result, highly sensitive planar graphene and highly stretchable crumpled graphene (CG) were rationally connected to effectively modulate the sensitivity and stretchability of the device. For the stretching mode, the device showed a gauge factor (GF) of 20.1 with 105% tensile strain. The sensitivity of the device was relatively high in this large working range, and the device could endure a maximum tensile strain of 135% with a GF of 337.8. In addition, in the bending mode, the device could work in outward and inward modes. This work introduced a novel and simple method with which to effectively monitor sensitivity and stretchability at the same time. More importantly, the method could be applied to other material categories to further improve the performance.

scholarly journals STUDY ON NONLINEAR PAVEMENT RESPONSES OF LOW VOLUME ROADWAYS SUBJECT TO MULTIPLE WHEEL LOADS / NETIESINĖS KELIO DANGOS PRIKLAUSOMYBĖS NUO MAŽO INTENSYVUMO KELIŲ, VEIKIAMŲ DAUGKARTINĖMIS RATŲ APKROVOMIS, TYRIMAS

2011 ◽  
Vol 17 (1) ◽  
pp. 45-54 ◽  
Author(s):  
Minkwan Kim ◽  
Joo Hyoung Lee
Keyword(s):  
Finite Element ◽  
Numerical Study ◽  
Asphalt Pavement ◽  
Three Dimensional ◽  
Nonlinear Behavior ◽  
Element Model ◽  
Element Analysis ◽  
Nonlinear Stress ◽  
Low Volume ◽  
Stress Dependent

This paper describes numerical analyses on low volume roads (LVRs) using a nonlinear three-dimensional (3D) finite element model (FEM). Various pavement scenarios are analyzed to investigate the effects of pavement layer thicknesses, traffic loads, and material properties on pavement responses, such as surface deflection and subgrade strain. Each scenario incorporates a different combination of wheel/axle configurations and pavement geomaterial properties to analyze the nonlinear behavior of thinly surfaced asphalt pavement. In this numerical study, nonlinear stress-dependent models are employed in the base and subgrade layers to properly characterize pavement geomaterial behavior. Finite element analysis results are then described in terms of the effects of the asphalt pavement thickness, wheel/axle configurations, and geomaterial properties on critical pavement responses. Conclusions are drawn by the comparison of the nonlinear pavement responses in the base and subgrade in association with the effects of multiple wheel/axle load interactions. Santrauka Straipsnyje aprašoma skaitinė mažo intensyvumo kelių analizė, taikant netiesinį—erdvinį baigtinių elementų modelį. Skirtingi dangų paviršiaus variantai analizuojami siekiant ištirti, kokiąįtaką kelio dangos elgsenai, t. y. poslinkiams ir kelio pagrindo deformacijoms, turi dangų sluoksnių storiai, eismo apkrovos ir medžiagų savybės. Kiekvienas kelio dangos variantas turi skirtingas ratų arba ašies ir geometrinių savybių formas, kad būtų galima išanalizuoti netiesinę plonos asfalto dangos paviršiaus elgseną. Šioje skaitinėje analizėje nagrinėjami netiesiniai įtempių modeliai, kurie buvo taikomi pagrindo sluoksniams, siekiant tinkamai apibūdinti geometrinę kelio dangos elgseną. Baigtinių elementų analizės rezultatai toliau nagrinėjami atsižvelgiant į asfalto dangos storį ar ašies formą ir geometrines savybes, priklausomai nuo kritinės kelio dangos būklės. Išvados buvo gautos lyginant netiesines kelių dangos priklausomybes pagrindo sluoksnyje, atsižvelgiant į jų sąveiką su daugkartine ratų apkrova.

Three-dimensional centrifuge and numerical modeling of the interaction between perpendicularly crossing tunnels

2013 ◽  
Vol 50 (9) ◽  
pp. 935-946 ◽  
Author(s):  
Charles W.W. Ng ◽  
Thayanan Boonyarak ◽  
David Mašín
Keyword(s):  
Shear Stress ◽  
Tensile Strain ◽  
Control Volume ◽  
Three Dimensional ◽  
Vertical Direction ◽  
Stress Transfer ◽  
American Concrete Institute ◽  
Overburden Pressure ◽  
Novel Technique ◽  
Centrifuge Tests

Tunnel driving inevitably induces changes in stress and deformation in the ground, which could cause ultimate and serviceability problems to an adjacent tunnel. The effects of induced stress on an existing tunnel and crossing-tunnel interaction are still not fully understood. In this study, a series of three-dimensional centrifuge tests were carried out to investigate the responses of an existing tunnel in sand to the excavation of a new tunnel perpendicularly below it. Three-dimensional tunnel advancement was simulated using a novel technique that considers the effects of both volume and weight losses. This novel technique involves using a “donut” to control volume loss and mimic soil removal in-flight. To improve fundamental understanding of the stress transfer mechanism during the new tunnel advancement, measured results were back-analyzed three-dimensionally using the finite element method. The maximum measured settlement of the existing tunnel induced by the new tunnel constructed underneath was about 0.3% of tunnel diameter, which may be large enough to cause serviceability problems. The observed large settlement of the existing tunnel was caused not only by a sharp reduction in vertical stress at the invert, but also by substantial stress transfer of overburden pressure at the crown. The section of the existing tunnel directly above the new tunnel was compressed vertically because the incremental normal stress on the existing tunnel was larger in the vertical direction than in the horizontal direction. The tensile strain and shear stress induced in the existing tunnel exceeded the cracking tensile strain and allowable shear stress limit given by the American Concrete Institute.

scholarly journals THE INFERENCE OF THE CHANGES OF AXONAL TRANSPORT OF OPTIC NERVE BY DEFORMATIONS OF LAMINA CRIBROSA

2020 ◽  
Vol 20 (10) ◽  
pp. 2040027
Author(s):  
YUSHU LIU ◽  
LIPING MA ◽  
WEI GAO ◽  
ZHICHENG LIU ◽  
SHOUXIN WANG ◽  
...  
Keyword(s):  
Optic Nerve ◽  
Axonal Transport ◽  
Laser Scanning ◽  
Saline Water ◽  
Compressive Strain ◽  
Three Dimensional ◽  
Element Model ◽  
Lamina Cribrosa ◽  
Confocal Laser

Understanding the relationship between the changes in the axonal transport of the optic nerve (ON) and lamina cribrosa (LC) deformation will be helpful to estimate the degree of axonal transport block by measuring the LC deformation in vivo. First, the changes in the axonal transport of the ON were studied using an acute high intraocular pressure (IOP) model, which was established by perfusing saline water into the anterior chamber of cats. The IOP of cat was unilaterally elevated to and maintained at 30, 40, and 50[Formula: see text]mmHg. The axonal transport of the ON was examined by confocal laser scanning microscope. Then the deformations and stress distributions of the LC and ON were calculated using a three-dimensional finite element model of the LC microstructure including ON. The results showed axonal transport changes of ON increased with elevation of the IOPs. While Young’s modulus of the LC and ON were assumed as 0.1[Formula: see text]MPa and 0.03[Formula: see text]MPa, the numerical simulation results showed that LC had displacements of 0.02, 0.03, and 0.04[Formula: see text]mm backward at the IOPs of 30, 40, and 50[Formula: see text]mmHg, respectively. The calculated compressive strain applied to the ON were 0.0425, 0.0567, and 0.0709 under 30, 40, and 50[Formula: see text]mmHg IOP, respectively. The results of strain and stress analysis of LC and ON showed that the deformation of LC would compress the ON. The axonal transport abnormalities could be inferred by measuring the LC deformation in vivo.

Failure Analysis of Multi-Layered Thick-Walled Composite Pipes Subjected to Torsion Loading

2021 ◽  
Vol 1047 ◽  
pp. 25-30
Author(s):  
Tian Yu Wang ◽  
Marina Menshykova ◽  
Oleksandr Menshykov ◽  
Igor Guz
Keyword(s):  
Strain Distribution ◽  
Three Dimensional ◽  
Element Model ◽  
Shear Stresses ◽  
Elasticity Solution ◽  
Design Considerations ◽  
Reinforced Composite ◽  
Composite Pipes ◽  
Three Dimensional Elasticity ◽  
The Finite Element Model

In the current study multi-layered thick-walled fibre reinforced composite pipes under torsion loading are considered. To analyse the stress-strain distribution in the pipe the Finite Element model (ABAQUS) has been developed. Using the model the radial, hoop, axial and shear stresses have been calculated for different lay-ups of the fibre reinforced pipes, and modified Tsai-Hill failure coefficients have been computed. The validation of the model was done by comparing the results available in the literature and the semi-analytical three-dimensional elasticity solution. The dependence of the failure coefficient on winding angles and layers’ thickness was investigated and analyzed, and the appropriate design considerations have been suggested for four-layer pipes.

Analysis of the Dynamic Response for Saturated Asphalt Pavement under Moving Vehicle Loads by Three-Dimensional Finite Element Method

2011 ◽  
Vol 97-98 ◽  
pp. 305-310
Author(s):  
Rui Bo Ren ◽  
Li Tao Geng ◽  
Wen Yang Qi
Keyword(s):  
Finite Element ◽  
Dynamic Response ◽  
Asphalt Pavement ◽  
Three Dimensional ◽  
Element Model ◽  
Temporal And Spatial Distribution ◽  
Moving Vehicle ◽  
Dimensional Finite Element ◽  
Vehicle Loads ◽  
Three Dimensional Finite Element

The dynamic response of saturated asphalt pavement subjected to moving vehicle load is studied. Based on the porous media theory, a three-dimensional finite element model is developed and the temporal and spatial distribution of three directional stresses and strains are calculated in saturated pavement and compared with those in dry condition. The results show obvious difference between saturated and dry asphalt pavement, especially in asphalt layer.

scholarly journals Enhanced Flexible Pavement Performance Using Treated Compared to Untreated Aggregate Bases: A Comparative Case Study in the Southern United States

2021 ◽  
Vol 6 (8) ◽  
pp. 110
Author(s):  
Mena I. Souliman ◽  
Hemant GC ◽  
Zabi Mohammed
Keyword(s):  
Surface Roughness ◽  
Tensile Strain ◽  
Compressive Strain ◽  
Base Material ◽  
Fatigue Cracking ◽  
Base Layer ◽  
Pavement Performance ◽  
Comparative Case Study ◽  
Stabilizing Agents ◽  
The Impact

One of the important aspects of highway design is aggregates. Aggregates strength and consistency has an effect on pavement structure’s overall performance. The consistency of the base material near the site of the construction doesn’t always match the requirements of pavement construction and carrying quality aggregate raises the cost of construction. Stabilizing agents such as asphalt cement, lime, fly ash were used to improve the strength of these materials in order to make greater use of locally available materials. Layer materials present in the pavements and the structure of them influence pavement performance. The compressive strain and the tensile strain in the layer of subgrade and asphalt layer respectively are influenced by the stiffness of the base layer. The important aspects causing rutting and fatigue cracking are compressive strain in the top region of the subgrade layer and tensile strain at the bottom of the asphalt layer, respectively. In this research study, field performance (cracking, rutting, and surface roughness) of pavement sections with untreated and treated bases were collated to assess the impact of the stabilizing agents. The treated sections performed well significantly compared to the untreated sections in terms of pavement surface roughness and fatigue cracking. The treated sections performed higher than the untreated sections in terms of the cumulative average values of all 3 distresses with fatigue cracking averaging 5 times lower than the untreated sections. The combined IRI and rutting of treated sections averaged about 1.5 times and 0.11 inches smaller, respectively than those of untreated sections.

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