scholarly journals Enhanced CRCP Backcalculation Procedure and Interface Bond Assessment: Volume 3

2021 ◽  
Author(s):  
Yating Zhang ◽  
◽  
Jeffery Roesler ◽  
Keyword(s):  
Test Section ◽  
Sensitivity Study ◽  
Friction Model ◽  
Crack Spacing ◽  
Interface Bonding ◽  
Transverse Cracks ◽  
Element Analysis ◽  
K Value ◽  
Limited Impact ◽  
Bonding Condition

Falling weight deflectometer (FWD) testing is effective in evaluating the structural response of in-situ concrete pavements through the backcalculated pavement layer parameters. Since Continuously Reinforced Concrete Pavement (CRCP) has closely spaced transverse cracks, the traditional backcalculation assumption of an infinite slab can lead to significant errors in the backcalculated results. In this study, solutions for backcalculated k-value, elastic modulus of concrete (E), and effective thickness (heff) for different crack spacing have been derived from 2-D finite element analysis for both interior- and edge-loaded CRCP. AASHTO sensor configuration (0, 12 in, 24 in, 36 in.) was recommended for CRCP with crack spacing greater than or equal to 6ft, and an alternative solution for crack spacing of 4 and 5ft was proposed with AREA24. Crack load transfer efficiency (LTE) across transverse cracks had limited impact on backcalculated results if the LTE was greater than 80%. According to the sensitivity study, both positive and negative temperature differentials less than 16oF had limited impact on backcalculated parameters. As expected, the backcalulation values were very sensitive to the load plate’s longitudinal position relative to the transverse crack especially for crack spacings smaller than 8ft. For edge-loaded condition, it is important to drop within a 2-inch lateral offset from edge in order to achieve accurate backcalculated results. In addition, the over width of the base provided extra support to CRCP slab resulting in higher backcalculated heff. The proposed backcalculation procedure system was applied to the Tollway field CRCP test section with different crack spacing, reinforcement ratio, and base types. Finally, a procedure for evaluating the slab-base bonding condition using simplified friction model along with backcalculated heff was extended and applied to one of the CRCP test section on Illinois Tollway near Itasca and one on Interstate 57 near Effingham. Based on the analysis of friction coefficient from measured deflection basin, cement treated base (CTB) was shown to provide good support to CRCP slab given the interface bonding condition between slab and base is stable in the long-term (more than 20 years). The combination of warm mix asphalt (WMA) and CTB also has good performance, even though the dynamic modulus of asphalt changes with the temperature causing decreased interface bonding condition in the summer.

Improved Backcalculation Procedure for Continuously Reinforced Concrete Pavement

2018 ◽  
Vol 2672 (40) ◽  
pp. 336-347 ◽  
Author(s):  
Yating Zhang ◽  
Jeffery Roesler
Keyword(s):  
Reinforced Concrete ◽  
Load Transfer ◽  
Soil Layer ◽  
Concrete Pavement ◽  
Crack Spacing ◽  
Interface Condition ◽  
Slab Thickness ◽  
Transverse Cracks ◽  
Element Analysis ◽  
K Value

Falling weight deflectometer (FWD) testing is effective in evaluating the structural response of in-situ concrete pavements through the backcalculated pavement layer parameters. Specifically, the FWD data can be used to backcalculate the foundation layer and concrete stiffness or the soil layer stiffness, effective slab thickness, and slab–base interface condition. Since continuously reinforced concrete pavement (CRCP) has closely spaced transverse cracks, the traditional backcalculation assumption of an infinite slab can lead to significant errors in the backcalculated results. In this paper, solutions for backcalculated modulus of subgrade reaction ( k-value), elastic modulus of concrete ( E), and effective thickness ( heff) for different crack spacing have been derived from 2-D finite element analysis. AASHTO sensor configuration (0, 12, 24, 36 in.) was recommended for CRCP with crack spacing ≥6 ft, and an alternative solution for crack spacing of 4 and 5 ft was proposed with AREA24. Crack load transfer efficiency (LTE) across transverse cracks had limited impact on backcalculated results if the LTE was >80%. As expected, the backcalulation values were sensitive to the load plate’s longitudinal position relative to the transverse crack especially for crack spacings smaller than 8 ft. The proposed backcalculation method was applied to a field CRCP test section with different crack spacing, reinforcement ratio, and base types.

3D FEA Modeling of Hard Turning

2002 ◽  
Vol 124 (2) ◽  
pp. 189-199 ◽  
Author(s):  
Y. B. Guo ◽  
C. R. Liu
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Geometric Model ◽  
Friction Model ◽  
Dominant Factor ◽  
Analysis Model ◽  
Element Analysis ◽  
Plastic Properties ◽  
Fea Model ◽  
Model Predictions

A practical explicit 3D finite element analysis model has been developed and implemented to analyze turning hardened AISI 52100 steels using a PCBN cutting tool. The finite element analysis incorporated the thermo-elastic-plastic properties of the work material in machining. An improved friction model has been proposed to characterize tool-chip interaction with the friction coefficient and shear flow stresses determined by force calibration and material tests, respectively. A geometric model has been established to simulate a 3D turning. FEA Model predictions have reasonable accuracy for chip geometry, forces, residual stresses, and cutting temperatures. FEA model sensitivity analysis indicates that the prediction is consistent using a suitable magnitude of material failure strain for chip separation, the simulation gives reasonable results using the experimentally determined material properties, the proposed friction model is valid and the sticking region on the tool-chip interface is a dominant factor of model predictions.

Investigation and Analysis on Transverse Crack Spacing Distribution in Continuously Reinforced Concrete Pavement in China

2013 ◽  
Vol 690-693 ◽  
pp. 1817-1820
Author(s):  
Quan Man Zhao ◽  
Hong Liang Zhang ◽  
Yan Hui Wang
Keyword(s):  
Reinforced Concrete ◽  
Transverse Crack ◽  
Concrete Pavement ◽  
Crack Spacing ◽  
Transverse Cracks ◽  
Spacing Distribution ◽  
Field Investigations ◽  
The Us

The longterm field investigations in the US showed that punchouts were the most important distress in continuously reinforced concrete pavement (CRCP) and often developed in the cluster cracking with the crack spacing of 0.3m-0.6m. But, it was not sure whether punchouts were the most important distress in CRCP in China, so this paper carried out field investigations on several CRC pavements in China. Results showed that punchouts were the most serious distress and often occurred in cluster crack regions. Furthermore, this paper analyzed the transverse crack spacing distribution. Results showed that the transverse cracks spacing distribution followed Weibull’s distribution.

scholarly journals Finite Element Analysis of Sheet Metal FormingTaking Account of Nonlinear Friction Model

2008 ◽  
Vol 49 (573) ◽  
pp. 0995-0999 ◽  
Author(s):  
Koji HASHIMOTO ◽  
Eiji ISOGAI ◽  
Tohru YOSHIDA ◽  
Yukihisa KURIYAMA ◽  
Koichi ITO
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Sheet Metal ◽  
Friction Model ◽  
Nonlinear Friction ◽  
Element Analysis

scholarly journals Numerical investigation of leakage behaviour in long radius elbows

Water SA ◽  
2020 ◽  
Vol 46 (1 January) ◽  
Author(s):  
Moustafa S Darweesh ◽  
Osama S Hussien
Keyword(s):  
Finite Element Analysis ◽  
Empirical Equation ◽  
Sensitivity Study ◽  
Internal Diameter ◽  
Longitudinal Stress ◽  
Element Analysis ◽  
System Pressure ◽  
Pressure Area ◽  
The Relationship ◽  
Leakage Exponent

This paper focuses on the relationship between leakage opening areas and pressure heads for 90° long radius elbows under elastic limits using finite element analysis (SAP 2000). The results indicate that leakage opening areas grow linearly as the system pressure increases and the relation is described by the pressure–area slope (M). A sensitivity study was performed to show the effect of various parameters on M, as well as the leakage exponent (N). It was found that elbow internal diameter has the largest influence on the pressure–area slope, followed by the modulus of elasticity and finally elbow wall thickness. The longitudinal stress and Poisson’s ratio have a negligible effect on M. Furthermore, leak quantity is related to the pressure raised to a power ranging from 0.495 to 0.592. Regression analysis was used to derive an empirical equation to predict the pressure–area slope of round holes within elbows with different properties.  

scholarly journals A Bifurcation Analysis and Sensitivity Study of Brake Creep Groan

2021 ◽  
Vol 31 (16) ◽  
Author(s):  
Shaun Smith ◽  
James Knowles ◽  
Byron Mason ◽  
Sean Biggs
Keyword(s):  
Periodic Orbits ◽  
Degrees Of Freedom ◽  
Initial Conditions ◽  
Period Doubling ◽  
Nonlinear Behavior ◽  
Sensitivity Study ◽  
Friction Model ◽  
Model Parameters ◽  
Period Doubling Bifurcations ◽  
Simple Models

Creep groan is the undesirable vibration observed in the brake pad and disc as brakes are applied during low-speed driving. The presence of friction leads to nonlinear behavior even in simple models of this phenomenon. This paper uses tools from bifurcation theory to investigate creep groan behavior in a nonlinear 3-degrees-of-freedom mathematical model. Three areas of operational interest are identified, replicating results from previous studies: region 1 contains repelling equilibria and attracting periodic orbits (creep groan); region 2 contains both attracting equilibria and periodic orbits (creep groan and no creep groan, depending on initial conditions); region 3 contains attracting equilibria (no creep groan). The influence of several friction model parameters on these regions is presented, which identify that the transition between static and dynamic friction regimes has a large influence on the existence of creep groan. Additional investigations discover the presence of several bifurcations previously unknown to exist in this model, including Hopf, torus and period-doubling bifurcations. This insight provides valuable novel information about the nature of creep groan and indicates that complex behavior can be discovered and explored in relatively simple models.

Dynamic Analysis of Riser Release and Lowering

2010 ◽  
Author(s):  
Sampath Atluri ◽  
Nicole Liu ◽  
Anil Sablok ◽  
Tim Weaver
Keyword(s):  
Oil And Gas ◽  
Sensitivity Study ◽  
Floating Structure ◽  
Oil And Gas Development ◽  
Cfd Simulations ◽  
Element Analysis ◽  
Arctic Regions ◽  
Production Platform ◽  
Study Results ◽  
Floating Platforms

Oil and gas development in certain harsh environments, such as extreme storm prone areas or arctic regions, may require the floating production platform to be designed to enable it to be released from its risers and moorings and moved out of the way of the approaching threat. Such floating platforms generally employ an underwater disconnectable buoy to support the moorings and risers after the main platform is moved away. For a deep draft floating structure, the risers can be released from their support near the top of the platform and lowered through the hull to a disconnectable buoy. In such a case, the risers can be routed through I-tubes and lowered in a controlled manner using rigging during a normal release operation. However, an emergency disconnection may require lowering of the risers without guidance of rigging. To avoid damage to the risers and the buoy during the emergency disconnection, risers can be fitted with passive damping devices to limit the lowering riser speed. This paper presents the numerical efforts to define the emergency riser release and lowering procedure. CFD simulations were performed to evaluate the hydrodynamic behavior of a disconnected riser in a flooded I-tube with the controlling devices attached to the risers. Applying the CFD results, riser lowering performance was computed using finite element analysis method. Primary parameters that affect flexible riser behavior, including stress level and curvature, are identified and sensitivity study results are presented. This paper concludes that a safe and controlled riser release procedure and system is achievable.

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