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Sail-assisted propulsion is an important energy-saving technology in the shipping industry, and the development of foldable wingsails has recently become a hot topic. This type of sail is usually composed of multiple elements, and its performance at different folding configurations is very sensitive to changes in incoming airflow, which result in practical operational challenges. Therefore, original and optimized three-element wingsails (bare and concave) are modeled and simulated using the unsteady RANS method with the k-ω SST turbulence model. Next, certain key design and structural parameters (such as angle of attack, apparent wind angle, and camber) are employed to characterize the auxiliary propulsion performance, and the differences are explained in combination with the flow field details. The results show that, in the unfolded state, the aerodynamic performance of the concave wingsail is better than that of the bare wingsail, exhibiting higher lift coefficients, lower drag coefficients, and a more stable surface flow. In the fully folded state, wherein both the nose and flap are rotated, the thrust performance of the concave wingsail remains superior. Specifically, at an angle of attack of 8 degrees, the thrust coefficient of the concave wingsail is approximately 23.5% higher than that of the bare wingsail, indicating improved wind energy utilization. The research results are of great significance for engineering applications and subsequent optimization design. [ABSTRACT FROM AUTHOR]

The flapping wings of insects undergo large deformations caused by aerodynamic forces, resulting in cambering. Insect-mimetic micro wings for flapping-wing nano air vehicles mimic these characteristic deformations. In this study, a 2.5-dimensional insect-mimetic micro wing model for flapping-wing nano air vehicles is proposed to realize this type of wing. The proposed model includes a wing membrane, a leading edge, a center vein, and a root vein, all of which are modeled as shell elements. The proposed wing is a 2.5-dimensional structure and can thus be fabricated using polymer micromachining. We conducted a design window search to demonstrate the capabilities of the wing. The design windows, which are areas of desirable design solutions in the design parameter space, are iteratively searched using nonlinear finite-element analysis under quasi-steady aerodynamic modeling. Here, thickness is selected as a design parameter. The properties of real insects, polymer materials, and fabrication conditions are used to determine the other parameters. A fabricable design solution that generates sufficient camber is found from the design windows. [ABSTRACT FROM AUTHOR]

Sail-assisted propulsion is an important energy-saving technology in the shipping industry, and the development of foldable wingsails has recently become a hot topic. This type of sail is usually composed of multiple elements, and its performance at different folding configurations is very sensitive to changes in incoming airflow, which result in practical operational challenges. Therefore, original and optimized three-element wingsails (bare and concave) are modeled and simulated using the unsteady RANS method with the k-ω SST turbulence model. Next, certain key design and structural parameters (such as angle of attack, apparent wind angle, and camber) are employed to characterize the auxiliary propulsion performance, and the differences are explained in combination with the flow field details. The results show that, in the unfolded state, the aerodynamic performance of the concave wingsail is better than that of the bare wingsail, exhibiting higher lift coefficients, lower drag coefficients, and a more stable surface flow. In the fully folded state, wherein both the nose and flap are rotated, the thrust performance of the concave wingsail remains superior. Specifically, at an angle of attack of 8 degrees, the thrust coefficient of the concave wingsail is approximately 23.5% higher than that of the bare wingsail, indicating improved wind energy utilization. The research results are of great significance for engineering applications and subsequent optimization design.

It is still unclear how elastic deformation of flapping insect wings caused by the aerodynamic pressure results in their significant cambering. In this study, we present that a vein–membrane interaction (VMI) can clarify this mechanical process. In order to investigate the VMI, we propose a numerical method that consists of (a) a shape simplification model wing that consists of a few beams and a rectangular shell structure as the structural essence of flapping insect wings for the VMI, and (b) a monolithic solution procedure for strongly coupled beam and shell structures with large deformation and large rotation to analyze the shape simplification model wing. We incorporate data from actual insects into the proposed numerical method for the VMI. In the numerical analysis, we demonstrate that the model wing can generate a camber equivalent to that of the actual insects. Hence, the VMI will be a mechanical basis of the cambering of flapping insect wings. Furthermore, we present the mechanical roles of the veins in cambering. The intermediate veins increase the out-of-plane deflection of the wing membrane due to the aerodynamic pressure in the central area of the wing, while they decrease it in the vicinity of the trailing edge. As a result, these veins create the significant camber. The torsional flexibility of the leading-edge veins increases the magnitude of cambering. [ABSTRACT FROM AUTHOR]

In this paper, we present a method of calculating cornering stiffness for different camber angles. The method removes the need for measurement data at different camber angles. The camber angle is regarded as equivalent to a local shift of load in the contact patch from one half-side to the other. A simple model is presented to describe the load shift. The cornering stiffness from each side, accounting for their loads, is then assumed to contribute to the total stiffness. The load shift model is validated through two finite element models. Cornering stiffnesses given by the model for two different tires are then compared to the measurements. To show the universality of the method, its application to interpolated measurement data is shown. The proposed method shows promising results for moderate camber angles. [ABSTRACT FROM AUTHOR]

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Wheel alignment of a vehicle composed of toe, camber and caster is essential for stable driving. Among them, the toe angle can be easily adjusted in many commercial vehicles when misaligned. However, there have been many difficulties for a driver to directly detect the misalignment of the toe angle. To solve this problem, this paper proposes a novel system that detects misaligned toe angle in real-time by utilizing the lateral tire force and tire aligning moment. The system is largely divided into the lateral tire force model construction, tire aligning moment model construction, and misalignment detection. During the lateral tire force model and the tire aligning moment model construction, linearized recursive least squares are used to identify parameters necessary for the building of the models. Afterwards, during the misalignment detection, the misaligned toe angle is detected in real-time without additional sensors by estimating the slip angle of each wheel reflecting the toe angle effect based on these two models. The proposed system is verified by the vehicle dynamics software CarSim, and the simulation results show that misaligned toe angle can be successfully detected in real-time while driving. [ABSTRACT FROM AUTHOR]

The flapping wings of insects undergo large deformations caused by aerodynamic forces, resulting in cambering. Insect-mimetic micro wings for flapping-wing nano air vehicles mimic these characteristic deformations. In this study, a 2.5-dimensional insect-mimetic micro wing model for flapping-wing nano air vehicles is proposed to realize this type of wing. The proposed model includes a wing membrane, a leading edge, a center vein, and a root vein, all of which are modeled as shell elements. The proposed wing is a 2.5-dimensional structure and can thus be fabricated using polymer micromachining. We conducted a design window search to demonstrate the capabilities of the wing. The design windows, which are areas of desirable design solutions in the design parameter space, are iteratively searched using nonlinear finite-element analysis under quasi-steady aerodynamic modeling. Here, thickness is selected as a design parameter. The properties of real insects, polymer materials, and fabrication conditions are used to determine the other parameters. A fabricable design solution that generates sufficient camber is found from the design windows.

It is still unclear how elastic deformation of flapping insect wings caused by the aerodynamic pressure results in their significant cambering. In this study, we present that a vein–membrane interaction (VMI) can clarify this mechanical process. In order to investigate the VMI, we propose a numerical method that consists of (a) a shape simplification model wing that consists of a few beams and a rectangular shell structure as the structural essence of flapping insect wings for the VMI, and (b) a monolithic solution procedure for strongly coupled beam and shell structures with large deformation and large rotation to analyze the shape simplification model wing. We incorporate data from actual insects into the proposed numerical method for the VMI. In the numerical analysis, we demonstrate that the model wing can generate a camber equivalent to that of the actual insects. Hence, the VMI will be a mechanical basis of the cambering of flapping insect wings. Furthermore, we present the mechanical roles of the veins in cambering. The intermediate veins increase the out-of-plane deflection of the wing membrane due to the aerodynamic pressure in the central area of the wing, while they decrease it in the vicinity of the trailing edge. As a result, these veins create the significant camber. The torsional flexibility of the leading-edge veins increases the magnitude of cambering.

Purpose. The authors aim to determine the features of the operation of a steel-reinforced concrete span structure with beams reinforced with an I-beam, with their pre-stressing using the bending of a steel I-beam. Methodology. To manufacture a steel-reinforced concrete span structure, it was proposed to reinforce an I-beam with a camber, which is then leveled with the help of applied external loads. For practical convenience, the vertical external forces are replaced by horizontal forces that keep the metal I-beam in a deformed state and in this state it is concreted. After the concrete strength development, the external forces are removed and the metal I-beam creates the pre-stressing of the concrete. Findings. When determining stresses, checking calculations by analytical method and the method of modeling with the help of the ANSYS program were used. The stress diagrams along the lower and upper fibers of a metal I-beam and stresses in concrete in the upper and lower zones of the beam were constructed. The analysis of the results showed that the pre-bending of a metal beam can be used to create a pre-stressing, which improves the performance of steel-reinforced concrete span structures, increases their rigidity and allows using of such a structure to increase the balks of railway and highway bridges. Originality. In the paper, a study of the stress-strain state of steel-reinforced concrete beams of the railway span structure was carried out, taking into account the pre-stressing of the concrete. A method of manufacturing a steel-reinforced concrete beams is proposed, which provides pre-stressing of the reinforced concrete due to the bending of a steel I-beam. Practical value. As a result of the calculations, it was found that the structure, when manufactured by the specified method, has greater rigidity compared to reinforced concrete or metal beams. The height of the beam can be lower compared to reinforced concrete or metal span structures. These circumstances are essential for railway bridges, especially for high-speed traffic ones.

The objective of this study is to evaluate the accuracy of prestressed girder camber calculations compared with field-measured camber from two precast plants. Field data on 189 Missouri girders with initial camber measurements and 33 girders with later camber measurements were compared with girder camber calculations using the original Missouri DOT method. The measured initial camber was on average 23% greater than the calculated camber, with an RMSE of 20.6 mm (0.81 in.) and an average error of 35%. The camber at a later point in time was only 11% greater than the calculated camber, with a RMSE of 19.6 mm (0.77 in.) and an average error of 19%. A major source of the difference in the measured and calculated camber was the measurement error introduced by sag of the measurement string line used at the precast plant. Other errors related to the estimation procedure were, in order of importance, support conditions, daily temperature gradients, temporary temperature during curing, concrete strength/age, concrete modulus, and creep parameters. All have a significant impact on camber calculations, with changes in camber from 23% to 4%. Other factors, such as prestressing force, section properties, concrete density, strand eccentricity, shrinkage, humidity, and long-term time-dependent analysis method, were systematically investigated and found to have minor impacts (less than 5% change in camber). Incorporating modifications to account for the measurement line sag, overhang length, concrete strength, and curing temperature reduced the underprediction of camber to 1.3% with a RMSE of 14.9 mm (0.59 in.) and an average error of 21%. [ABSTRACT FROM AUTHOR]

The current camber prediction procedure in the PCI Design Handbook: Precast and Prestressed Concrete results in variations between the design and the actual camber. These variations create difficulties in maintaining the design thickness of the bridge deck and the design longitudinal profile. This research aims at enhancing the PCI design method of estimating long-term camber and deflection of prestressed concrete girders. Field measurements included monitoring cambers for a total of 94 girders from fabrication through the erection at bridge sites. Compressive strength and modulus of elasticity were measured for several girders, and the results were compared with the design properties. The differences between the design and actual concrete properties were found to be the main reason for overestimation in camber and deflection. A modification to the PCI camber prediction method is proposed to improve the accuracy of predicting the erection camber based on field measurements and material tests on four types of bridge girders. [ABSTRACT FROM AUTHOR]

One of the most used tyre models is the so-called Magic Formula, which provides the contact forces and moments as a function of the tyre slips and normal load. Among the slip inputs, there is the spin–slip, which is defined as the combination of a camber component and a path-curvature component. The two components are related to each other by the camber reduction factor, for which only a few data have been reported in the literature. In addition, these data are often obtained from indirect measurements. In this work, an experimental procedure for the direct measurement of the camber reduction factor was devised, and applied to six specimens of motorcycle tyres (three front and three rear). The approach employs a rotating-disk machine, where the tyre is intrinsically subjected to path curvature. A specific aligning procedure to mitigate sideslip disturbances is introduced and employed during testing. The three specimens of the rear tyres tested showed a camber reduction factor that was close to zero, which is the typical result suggested by the literature. On the contrary, the three specimens of front tyres showed slightly negative values, i.e., the camber component increased with respect to the curvature component. The results suggest that the classic assumption of a zero camber reduction factor does not hold valid for all motorcycle tyres. [ABSTRACT FROM AUTHOR]

In this paper, we present a method of calculating cornering stiffness for different camber angles. The method removes the need for measurement data at different camber angles. The camber angle is regarded as equivalent to a local shift of load in the contact patch from one half-side to the other. A simple model is presented to describe the load shift. The cornering stiffness from each side, accounting for their loads, is then assumed to contribute to the total stiffness. The load shift model is validated through two finite element models. Cornering stiffnesses given by the model for two different tires are then compared to the measurements. To show the universality of the method, its application to interpolated measurement data is shown. The proposed method shows promising results for moderate camber angles.

Accurate predictions of concrete compressive strength are critical for designers to effectively estimate the camber, deflections, and prestress losses of precast, prestressed concrete elements. A methodology that relies on regional concrete bridge girder strength test results is proposed for predicting expected concrete compressive strength. Strength data collected from precast, prestressed concrete plants were manipulated by the use of a strength-difference approach to facilitate American Concrete Institute 214R-11 analysis methods. The data set was used to evaluate five other empirical prediction model forms. When implemented using an Alabama regional data set, the methodology resulted in markedly more accurate predictions of expected concrete strength at prestress transfer and at 28 days compared with current practice. [ABSTRACT FROM AUTHOR]

The implementation of morphing wing applications in aircraft design has sparked significant interest as it enables the dimensional properties of the aircraft to be modified during flight. By allowing manipulation of the 2D and 3D parameters on the aircraft’s wings, tail surfaces, or fuselage, a variety of possibilities have arisen. Two primary schools of thought have emerged in the field of morphing wing applications: the mechanisms school and the smart surfaces approach that uses shape-memory materials and smart actuators. Among the research in this field, the Fishbone Active Camber (FishBAC) approach has emerged as a promising avenue for controlling the deflection of the wing’s trailing edge. This study revisits previous research on morphing wings and the FishBAC concept, evaluates the current state of the field, and presents an original design process flow that includes the design of a unique and innovative UAV called the Stingray within the scope of the study. A novel morphing concept developed for the Stingray UAV, Rear Spar Articulated Wing Camber (RSAWC), employs a fishbone-like morphing wing rib design with rear spar articulation in a cost-effective manner. The design process and flight tests of the RSAWC are presented and directly compared with a conventional wing. Results are evaluated based on performance, weight, cost, and complexity. Semi-empirical data from the flight testing of the concept resulted in approximately a 19% flight endurance increment. The study also presents future directions of research on the RSAWC concept to guide the researchers.

This paper demonstrates that a discrete coupled-adjoint aeroelastic shape optimization can be made more efficient with the use of different mesh-deformation algorithms for the fluid-structure interaction (FSI) simulations and the coupled-adjoint calculations within the optimization loop. Mesh deformation using radial basis functions (RBF) with only a subset of surface points is popular due to the efficiency and mesh quality produced by the technique. However, this technique can reduce the rate of convergence of the coupled-adjoint and even prevent the coupled-adjoint equations from converging. This paper proposes a hybrid mesh-deformation strategy to improve the efficiency of coupled-adjoint optimizations: use the RBF method with a data-reduction algorithm when deforming the mesh within FSI simulations but use the Delaunay graph mapping (DGM) method in the coupled-adjoint procedure. The DGM method increases the rate of convergence of the coupled-adjoint matrix, relative to the RBF approach with a data-reduction algorithm, with the additional benefit of being a faster method. Using this hybrid approach, an optimization in which lift and pitching-moment constraints are satisfied within the FSI simulation is performed. The results of the optimization, and the effects of the hybrid approach, are presented. [ABSTRACT FROM AUTHOR]

A frequency-domain linearized Euler solver is employed to perform aeroelastic analysis for predicting the control surface buzz onset condition. The predictive capability of the linearized Euler solver for control surface buzz is verified by comparing the predicted onset buzz Mach numbers with wind tunnel data of the National Aerospace Plane flutter model. Using a generic fighter wing as the test bed, a parametric study is performed to investigate the impact of aerodynamic and structural parameters on control surface buzz. These parameters include angle of attack, hinge line sweep angle, airfoil camber, hinge stiffness, and control surface mass. The results of this parametric study suggest that the empirical buzz avoidance criterion used by aerospace industry to avert the buzz problem is oversimplified and should be revised. [ABSTRACT FROM AUTHOR]

Coastal vulnerability and its physical, economic and social consequences at national and international scales is of high scientific, political and policy interest. Anthropogenic climate change and coastal erosion threaten the very fabric of a society. Indications, that coastal hazards are impacting diverse coastal areas severely across the world, and it is no longer a vague future threat that can't be ignored. Rising eustatic sea levels synthesized by the growing frequency and scale of coastal hazards like storm surges, coastal erosion and coastal landslides threaten low-lying and unprotected coastal areas in the United Kingdom even if they have coastal defenses. However, there is still significant uncertainty about the degree of vulnerability along different coastal stretches, particularly in England. To fill this uncertainty, the current study estimated the coastal vulnerability of the coastal erosion hotspot Camber, England, by establishing a coastal vulnerability index. This index was developed by compounding various existing parameters and termed as Erosion Coastal Vulnerability Index (ECVI). Results illustrate that 67% of coastal area fall between high and very high vulnerability categories, and current coastal defenses are not strong enough to tackle the severe coastal erosion in Camber. Within the evaluation, thematic maps were generated to enable the intensity of the vulnerability for different coastal stretches to be identified. The evaluated vulnerable hotspot should be treated urgently by regional and national policy organizations to ameliorate the impacts of coastal erosion and other associated risks. Without action, the hotspot is likely to encounter unprecedented new vulnerabilities, disasters and humanitarian catastrophes. The current study results allow for a local, regional and national comparison that may help to evaluate changes in coastal erosion vulnerability. [ABSTRACT FROM AUTHOR]

A lot of studies have been conducted to introduce self-prestress to structures using Fe-based shape memory alloys (Fe-SMAs). Technology to introduce self-prestress using Fe-SMAs can resolve the disadvantages of conventional prestressed concrete. However, most of the research to introduce a self-prestress force to a structure using Fe-SMAs has been focused on using Fe-SMAs for the repair and strengthening of aging structures. Therefore, in this paper, a study was conducted to introduce self-prestress into a new structure. To this end, in this paper, an experimental study was conducted to evaluate the flexural behavior of self-prestressed concrete slabs with Fe-SMA rebar. Nine specimens were built with consideration of the amount and activation of Fe-SMA rebars as experimental variables. The Fe-SMA rebars used in the specimens exhibited recovery stress of about 335 MPa under the conditions of a pre-strain of 0.04 and a heating temperature of 160 °C. Activation of the Fe-SMA rebars by electrical resistance heating applied an eccentric compression force to the specimen to induce a camber of 0.208–0.496 mm. It was confirmed through a 4-point bending test that the initial crack loads of the activated specimens were 40~101% larger than that of the non-activated specimens. However, the ultimate loads of the activated specimens showed a difference within 3% from that of the non-activated specimens, confirming that the effect of activation on improving the ultimate strength was negligible. Finally, it was confirmed that repetitive activation of the Fe-SMA rebar could repeatedly apply compressive force to the slab. [ABSTRACT FROM AUTHOR]

In this study, performance of a right-swing turbine with a cambered hydrofoil was analyzed by CFD numerical simulations to assess its stability and power efficiency. It is found from the analysis that the right-swing trajectory, which is close to the kinematics of flying or swimming creatures, has advantages over the left-swing trajectory in terms of stability with a slight loss of the power efficiency. A cambered hydrofoil can be utilized to offset this loss, but doing so negatively affects the stability at the turning positions of the flapping motion. Consequently, in order to guarantee stability and high efficiency of a right-swing hydrofoil turbine, camber shapes adjustable at the positions of flapping motion, which is an excellent feature of flight and swimming creatures, are mandatory. Eventually, the analysis results of this study will be utilized to develop a high-performance flapping hydrofoil turbine.

Non-pneumatic tyres (NPT) provide a greater advantage over the pneumatic type owing to their construct which increases the reliability of the tyre operation and effectively reduces maintenance involved. Analysing the aerodynamic forces acting on a NPT becomes a crucial factor in understanding it's suitability for practical implementation. In the present work, the aerodynamic performance of a NPT using CFD tool – SimScale® is studied. This work includes a comparative study of a pneumatic tyre, a NPT with wedge spokes and a NPT with hexagonal spokes (NPT-HS). The effect of air velocity, steering (yaw) angle and camber angle on the aerodynamic performance of the NPT-HS is evaluated using CFD. By increasing the steering angle from 0° to 15°, the lift coefficient decreases by 37% approximately at all velocities. Whereas drag coefficient initially decreases by 21% till 7.5° steering angle and then starts increasing. Increasing camber angle from 0° to 1.5°, both drag and lift coefficients goes on decreasing by approximately 7% and 27% respectively. [ABSTRACT FROM AUTHOR]

One of the most used tyre models is the so-called Magic Formula, which provides the contact forces and moments as a function of the tyre slips and normal load. Among the slip inputs, there is the spin–slip, which is defined as the combination of a camber component and a path-curvature component. The two components are related to each other by the camber reduction factor, for which only a few data have been reported in the literature. In addition, these data are often obtained from indirect measurements. In this work, an experimental procedure for the direct measurement of the camber reduction factor was devised, and applied to six specimens of motorcycle tyres (three front and three rear). The approach employs a rotating-disk machine, where the tyre is intrinsically subjected to path curvature. A specific aligning procedure to mitigate sideslip disturbances is introduced and employed during testing. The three specimens of the rear tyres tested showed a camber reduction factor that was close to zero, which is the typical result suggested by the literature. On the contrary, the three specimens of front tyres showed slightly negative values, i.e., the camber component increased with respect to the curvature component. The results suggest that the classic assumption of a zero camber reduction factor does not hold valid for all motorcycle tyres.

Flapping-wing aircraft (FWA) operates in a flight mode that mimics natural flyers, such as birds, bats and insects. For large scale bird-inspired flapping wings aircraft, the design of airfoil parameters is crucial to improving the aerodynamic performance. In order to study the effect of camber on the aerodynamic characteristics, we developed four different airfoils with a chord length of 12 cm. The cambers of airfoils are respectively 30 mm, 25 mm, 20 mm and 15 mm. A numerical investigation into the effects of camber on aerodynamic performance is carried out through COMSOL Multiphysics software using Fluid–Structure Interaction (FSI) module. In this work, the fluid–structure module employs the Navier–Stokes equations coupled with a solid stress–strain physics module and a moving mesh module. The three-dimensional (3D) flapping wing computational models with different cambers are built. The results show that certain camber of airfoil can improve the aerodynamic characteristics of flapping wing.

This research investigates the behavior of encased steel composite beams within steel fiber reinforced concrete (SFRC) in straight and preflex beams, using nonlinear analysis. ABAQUS FEA software has been adopted. Composite steel beams encased in fiber reinforced concrete are analyzed and a comparison is made with available experimental results. Good agreement with the experimental results is observed. Upwards camber of the steel section is introduced on the steel joist. It’s found that the preflex section can increase the ultimate load capacity by 10% and decrease midspan displacement by 13% of the same beams without the preflex steel section. Steel fiber dosages, compressive strength, modulus of rupture are examined. The effect of cambering and mesh refinement is also investigated. The physical properties of SFRC are calculated through testing at the UTA Civil Engineering Laboratory Building. In total, nine (4″ x 8″) cylindrical specimens, nine (6″ x 12″) cylindrical specimens, and nine (6″ x 6″ x 20″) beam specimens were produced and tested for their compressive strength, tensile strength, and modulus of rupture after 28 days of curing. The addition of steel fiber will lead to a significant increase in tensile strength and modulus of rupture of concrete. Adding 1% steel fibers by volume can increase the load capacity by 33% and decrease the midspan displacement by 70% in comparison to the same beam using plain concrete. The increase in steel fibers and cambering shows an improvement to the flexural capacity and cracking point of the beam, which can provide mo re strength to structures such as long-span bridges.

Toe-in and camber on the front and rear wheels are two important parameters which affect tire abrasion of automobiles, driving and braking stability, front wheel shimmy and so on. The reasonable matching calculation between Toe-in and camber has always been a problem in the design of vehicle four-wheel alignment parameters. The cornering property is one of the key factors influencing the matching accuracy between toe-in and camber and it is a difficulty to establish the matching formula of the two. In order to obtain a more accurate matching relationship，A new formula of matching toe-in and camber based on the existing research results assuming that the tires are rigid, which considers the cornering characteristics of tires, is established to decrease the tire abrasion，front wheel shimmy and increase the driving and braking stability of automobiles. The new formula is verified by testing the front wheel sideslip and tire abrasion of a truck model. The test results show that the matching formula adjusted toe-in and camber is reasonable. From previous studies and the principle of balance between lateral force of camber and cornering force of toe-in, a new calculation method to match toe-in with camber reasonably is proposed.

A lot of studies have been conducted to introduce self-prestress to structures using Fe-based shape memory alloys (Fe-SMAs). Technology to introduce self-prestress using Fe-SMAs can resolve the disadvantages of conventional prestressed concrete. However, most of the research to introduce a self-prestress force to a structure using Fe-SMAs has been focused on using Fe-SMAs for the repair and strengthening of aging structures. Therefore, in this paper, a study was conducted to introduce self-prestress into a new structure. To this end, in this paper, an experimental study was conducted to evaluate the flexural behavior of self-prestressed concrete slabs with Fe-SMA rebar. Nine specimens were built with consideration of the amount and activation of Fe-SMA rebars as experimental variables. The Fe-SMA rebars used in the specimens exhibited recovery stress of about 335 MPa under the conditions of a pre-strain of 0.04 and a heating temperature of 160 °C. Activation of the Fe-SMA rebars by electrical resistance heating applied an eccentric compression force to the specimen to induce a camber of 0.208–0.496 mm. It was confirmed through a 4-point bending test that the initial crack loads of the activated specimens were 40~101% larger than that of the non-activated specimens. However, the ultimate loads of the activated specimens showed a difference within 3% from that of the non-activated specimens, confirming that the effect of activation on improving the ultimate strength was negligible. Finally, it was confirmed that repetitive activation of the Fe-SMA rebar could repeatedly apply compressive force to the slab.

Recently, various studies for the use of Fe-based shape memory alloy (Fe-SMA) in the construction field have been widely conducted. However, most of the studies for using Fe-SMA are carried out for applying Fe-SMA for strengthening deteriorated structures. However, if Fe-SMA is used as a reinforcement for new structures, the disadvantages of conventional prestressed concrete can be effectively solved. Therefore, in this work, an experimental study was conducted to evaluate the flexural behavior of concrete beams in which Fe-SMA rebars were used as tensile reinforcement. For the study, ten specimens were constructed with the consideration of the cross-sectional area and activation of Fe-SMA rebars as experimental variable. Activation of the Fe-SMA rebars by electrical resistance heating applied an eccentric compressive force to the specimen to induce camber. The camber increased by an average of 0.093 mm as the cross-sectional area of the Fe-SMA rebar increased by 100 mm2. It was also confirmed through the four-point bending tests that the initial crack loads of the activated specimens were 47.6~112.8% greater than those of the nonactivated specimens. However, the ultimate strength of the activated specimens showed a slight difference of 3% to those of the nonactivated specimens. Therefore, it was confirmed that the effect of Fe-SMA activation on the ultimate strength of specimens was negligible.

The shape of a hot rolled strip is a main indicator of its quality, and camber is a significant defect arising from problems in shape quality. Differences in the bearing clearance of the two sides of a rough mill can cause a crossed roller, which leads an imbalance in the rolling force and, thereby, camber. A camber defect adversely affects product quality and the stability of the subsequent finish-rolling production process. The simulation and control of asymmetric shapes is one of the hottest topics in the field of modern strip rolling. To solve this problem and enhance the quality and precision of the strips produced, exploring and analyzing the problem of camber in hot rough rolling is necessary. This study investigated the generation of camber in the 1580 mm roughing mill R2 of a steel plant during the hot-continuous-rolling process. This paper established a three-dimensional elastic-plastic dynamic coupling model of the rolls and slab using the finite element (FE) analysis software ABAQUS/Explicit. In addition, the paper used a data analysis method based on the node-set coordinate output. By balancing the relationship between computational precision and efficiency, the study found the FE model to run stably. Using the proposed model, the paper systematically investigated the influence of cross position and angle on the camber, slab wedge, and amount of rolling force under different conditions. Based on the FE results, the paper then characterized the influence law for the occurrence of a cross roll with respect to bearing clearance and slab camber. Numerical examples demonstrate that the relationship between the camber and cross-angle position is linear, and that between the slab camber and clearance is a quadratic curve.

Building an intentional vertical curve into a precast concrete girder formwork system and the prestressing strand layout creates a girder with a prefabricated vertical curvature known as precamber. Precamber is an effective technique for matching the roadway profile grade for girders fabricated with a monolithic deck slab. For superstructures with a cast-in-place concrete deck, this technique helps meet challenging vertical clearance requirements and reduces the slab haunch buildup associated with significant vertical curve profiles. This paper highlights the fabrication and design of precambered girders to raise awareness and share technical knowledge about this effective but underused application of precast concrete. [ABSTRACT FROM AUTHOR]

Aimed at the frequently occurred problem of slab camber in rough rolling of hot strip mills, the main factors causing slab camber, including the difference in longitudinal stiffness of the mill on both sides, incoming wedge and running deviation of rolled pieces, were analyzed by combining with the spring equations and analytical method in this paper, and the corresponding adjustment values were respectively calculated. Based on rolling force difference on both sides, the tilting control model of slab camber was established. This model could reflect the quantitative relationship between the main factors and camber, such as the difference in longitudinal stiffness of the mill on both sides, incoming wedge and running deviation of rolled pieces, etc., and then the tilting values of roll gap for controlling camber were calculated in each pass of the rough rolling mill. Comparing with the real values by off-line verification, the averaged ratio of measured and calculated values is 0.977. The results show that the tilting values of roll gap can be estimated by the tilting control model of slab camber in each pass. Since putting the model into a 2250 mm hot strip mill, the camber values not complying with tolerance declined from 24.88% to 6.62%. By improving the control effect of camber, the slab camber problem has been greatly eased.

Nano rotor is of great value in military and civilian applications. Due to its nano size, it works at an ultra-low Reynolds number and aerodynamic performance deteriorates dramatically. The bio-inspired nano rotor is carried out to improve the rotor propulsive performance. Unsteady vortex lattice method (UVLM) model is established fully considering the influence of induced drag and wake vortex distortion on aerodynamic forces. The aim is to quickly and accurately simulate the flow field around the bio-inspired nano rotor and to efficiently perform the aerodynamic calculation to optimise the design of the bio-inspired rotor. The rotor parameters and motion parameters such as aspect ratio, taper ratio and camber are studied using UVLM. It is found that the aerodynamic performance of the rotor increased with the aspect ratio. The quality factor changes parabolically with the taper ratio and camber, and there is an optimal value for the ratio and camber, respectively. The influences of pitching angle and frequency are investigated as well. Results show that the bio-inspired motion improves the propulsion performance of nano rotor.

The roll deflection during hot rolling can result in uneven thickness distribution across the width of a plate (crown). A conventional rolling mill is equipped with bending systems that can control this convex shape of the plate. However, the determination of the proper bending load is very complicated as the plate crown is influenced by the rolling conditions. In this paper, a thermo-mechanical Finite Element Model on LS-DYNATM software was utilized to predict crown evolution based on the rolling conditions in order to determine the setting values for achieving the target crown. The simulation results were compared and verified with actual industrial data for rolling force, plate temperature and plate crown. This approach is essential for pass schedule design and process parameter optimization in order to achieve the desired product quality. [ABSTRACT FROM AUTHOR]

Numerical simulations are conducted to investigate the impacts of airfoil thickness, the angle of attack and camber on the airfoil-gust interaction noise in transonic flows where locally supersonic regimes and terminating shocks are present. The conclusions about the geometry effects based on the extensively studied subsonic cases are revisited. With the increase of airfoil thickness, the sound generation is reduced in the downstream direction as in subsonic flows. More sound is produced in the upstream direction for thicker airfoils due to the non-uniform mean flow and shocks in the near field. The compensative effect makes the overall sound reduction by the airfoil thickness less than the subsonic cases despite the significant difference in the radiation patterns. The acoustic responses to the single frequency gusts are sensitive to the airfoil angle of attack in transonic flows. However, the overall differences are reduced when multiple wavenumber components are superposed in isotropic turbulence, and the sound pressure levels are therefore close as in subsonic flows. Similarly, the significant variations in single frequency acoustic responses by airfoil camber are averaged by the superposition of various wavenumber components. However, apparent variations are still found in the upstream direction, especially for the turbulences with small integral length scales. [ABSTRACT FROM AUTHOR]

Development in production technology has increased the need for high productive efficiency and effective utilization of machines. Tires, paper, rexin, and other rubber-based products are produced by using calendar roll machines. Web wrinkling, torn material, misaligned cutting, slitting, poor adhesion and laminate characteristics are the major errors in a calendar roll machine. The geometry, camber of rollers play a major role for most of the errors stated. This paper focuses on the experimental investigations carried out for cambering the rolls in-site (without removing), through grinding process with newly modeled equipment. The results obtained through in-site grinding are compared and discussed. It is observed that in-site grinding reduces the machine idle time by three-fourth of the normal roll grinding process and avoids the machine characteristic errors. New equipment comfortably eliminates the wrinkles and improves the quality of the rubber-coated fabric with the variation in thickness only between 1 and 2 µm. [ABSTRACT FROM AUTHOR]