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Optimal control settings (camber scheduling) can be used by aircraft to minimize drag at various operating conditions during flight. In this work, camber schedules for minimum drag on the NASA Ikhana are obtained over a range of lift coefficients. A modern numerical lifting-line algorithm is used to predict the lift and drag of the aircraft as a function of operating condition and wing section shape (airfoil camber). The SLSQP optimization algorithm is used to solve for the camber schedule that minimizes drag for a given operating condition. The process is repeated, varying the number of control sections to evaluate the benefit of additional control sections in minimizing drag on the aircraft. Results show that there are diminishing returns with increased numbers of control sections. For the NASA Ikhana, the limit on the number of control sections added before diminishing results were obtained was found to be 2 control sections. With 2 control sections the NASA Ikhana achieved between a 4.5% and 26.3% reduction in drag for lift coefficients between 0.1−0.9 when compared to the baseline Ikhana with no control sections. Adding an additional 2 control sections reduced the drag by less than 0.75%. Results from the optimization can be used in flight algorithms to schedule camber during flight such that drag and fuel burn are minimized. Results can also be used to inform the design of future aircraft with distributed control surfaces, especially in the growing small unmanned aerial vehicle (UAV) market where many designs are aerodynamically less efficient than commercial and research aircraft, such as the NASA Ikhana.

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.

Alpine skis have changed dramatically in the last century. Long and straight wood skis have evolved into shorter lengths and now contain a plethora of modern materials. Shaped skis have become the norm. Today’s skis also offer a variety of waist widths and shapes to cater to specific uses. By studying how skis have evolved, it is possible to gain insight into how the design of alpine skis has progressed. To do so, the mechanical properties of 1016 skis, from the 1920s to 2019, were measured with a machine developed at the University of Sherbrooke. The resulting data are used to calculate various geometric, stiffness and performance parameters. The evolution of these parameters over the years is analyzed. This analysis provides a better understanding of the evolution of ski design and shows when the introduction of new materials and shaping concepts has changed the way skis are designed.

The paper investigates experimentally the low Reynolds number flow ( R e c = 50 , 000 ) around a model that approximates a NACA 4415 airfoil and the control of separation using periodic surface motion. Actuation is implemented by bonding two Macro Fiber Composite patches to the underside of the suction surface. Time-resolved measurements reveal that the peak-to-peak displacement of the surface motion is a function of both the amplitude and frequency of the input voltage signal but the addition of aerodynamic forces does not cause significant changes in the surface behavior. The vibration mode is uniform in the spanwise direction for frequencies below 80 Hz; above this frequency, a secondary vibration mode is observed. The flow around the unactuated airfoil exhibits a large recirculation region as a result of laminar separation without reattachment and consequently produces relatively high drag and low lift forces. Various actuation frequencies were examined. When actuated at V f + = 2 . 0 , the spectra in the vicinity of the trailing edge and near-wake were found to be dominated by the actuation frequency. Sharp peaks appear in the spectra suggesting the production of Large Coherent Structures at this frequency. The increased momentum entrainment associated with these enabled a significant suppression of the separated region. The result was a simultaneous increase in C L and decrease in C D and therefore a large increase in the L ∕ D ratio. In addition, a delay in the onset of stall results in a significant increase in the maximum achievable lift.

Wing morphing is the manipulation of a wing shape to influence aerodynamics. Wing morphing has significant aerodynamic advantages over traditional flaps, including increased efficiency and control. The USU Aerolab specializes in morphing aircraft and is currently working with the Air Force Research Lab on morphing straight wings [1-4]. The purpose of this project is to identify methods for applying morphing technologies to swept-wing aircraft. These methods are then used to create a morphing wing aircraft to demonstrate the efficiency and control of morphing flight with a swept wing., https://digitalcommons.usu.edu/fsrs2019/1003/thumbnail.jpg

External and internal façade walls at historical buildings in Cairo usually comprise projections that are carried on corbels. The corbels are usually built of stone, timber or composite (i.e. timber and stone). These masonry façade projections are usually vulnerable to structural damages and failures due to several causes, which can lead to successive failure and collapse of the timber roofs that support on them, so that the whole building maybe abandoned, in addition to possible injuries and death of passing-by during façade's falling-down and routes' blocking from its ruins. The present work studies the masonry façade projections of the historical medieval buildings in Cairo and their supporting stone corbels to determine their structural behaviour and failure mechanism. It reveals the significances of distinctive cambering of the corbels to the stability of the projections. Besides, a proposal for strengthening of the projection walls and corbels is provided.

RESUMEN: Este trabajo de fin de grado consiste en el desarrollo del sistema de suspensión del eje tanto delantero como trasero, para un prototipo de la clase “Urban Concept Car”, el cual disputará la competición Shell eco-marathon. Se analizará y evaluará su comportamiento cinemático y dinámico, mediante diversas situaciones que puede experimentar en dicha competición. Además, se harán pruebas para saber si cumpliría las inspecciones previas a la carrera. Se estudiarán todos los componentes para saber cuál son sus deformaciones y tensiones. Trabajaremos con el programa Adams View para hacer todas las comprobaciones y simulaciones, el cual es uno de los programas más utilizado para este tipo de estudios. Para todo ello, previamente vamos a conocer los antecedentes de las suspensiones. También nos amoldaremos a las capacidades de trabajo que tiene el instituto IES Nuestra Señora de los Remedios, con el que colaboramos. ABSTRACT: This end-of-degree work consists of the development of the front and rear axle suspension system, for a prototype of the "Urban Concept Car" class, which will contest the Shell eco-marathon competition. Your kinematic and dynamic behavior will be analyzed and evaluated, through various situations you may experience in such competition. In addition, tests will be carried out to see if it would comply with pre-race inspections. All components will be studied to know their deformations and stresses. We will work with the Adams View program to do all the checks and simulations, which is one of the most used programs for this type of studies. For all this, we will know the background of the suspensions beforehand. We will also adapt to the working capacities of the IES Nuestra Señora de los Remedios institute, with which we collaborate. Grado en Ingeniería Mecánica

The Utah Transportation Center (UTC) as well as the Mountain Plains Consortium, sponsored a study to investigate the long-term performance of a deck bulb tee girder bridge. The bridge in question is located in Nibley, Utah and was erected in early 2016. Temperature and prestress losses were analyzed from embedded instrumentation placed within two of the bridge girders before casting. These two girders contained a total of 50 thermocouples and 16 vibrating wire strain gauges. These instruments were placed at the mid-span and end of an exterior girder and the mid-span, quarter-span, and end of a center girder in order to effectively monitor the bridge response in one quarter of the bridge superstructure. The monitoring performed with the thermocouples included the temperature of the girders during curing, weekly maximum and minimum temperatures compared to methods for predicting the average bridge temperature, maximum and minimum thermal gradients at each of the five selected cross sections compared to Code thermal gradients, and thermal camber by measured temperature compared to models to predict thermal gradients. The 16 strain gauges measured prestress losses at four girder cross-sections, which were compared to two predictive methods provided by AASHTO as well as a method by PCI. An additional comparison of the equations provided by AASHTO and a newly available equation used for determining the modulus of elasticity of concretes with a compressive strength of 6,000 ��� 12,000 psi was performed. Additional exterior instrumentation were provided by Bridge Diagnostics Inc. (BDI) in order to monitor short-term changes within the bridge. A total of 8 strain gauges were attached to the exterior of the girders with 6 attached at the bottom face of 6 girders and 2 attached at the centroid of 2 girders. These sensors as well as the software and wireless data acquisition provided a method to measure the magnitude and frequency of the ranges of strain experienced by the Nibley Bridge.

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-DYNA&trade, 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.

Numerical modeling of the prestressing element that generates prestressed effect in beams has always been considered a big challenge. This research compares two methods of modeling; In the first method we used initial stresses predefined stress and in the second method we used the temperature strain. Concrete damage plasticity model (CDP) was used to model the non-linear behavior of concrete material and an elasto-plastic behavior was applied to ordinary and prestressed reinforcement. Truss elements were used to model ordinary and prestressed reinforcement embedded inside the concrete. As a result, Initial Temperature load method showed less error in bottom and top stresses and cambering of beam in comparison with the basic concept method, than predefined method.

Mahasarakham International Journal of Engineering Technology, 2, 1, 16-21

To study the rolling properties of a radial tire, an accurate 3D 195/60R14 tire model is established. The modal includes the geometric nonlinearity due to large deformation, material nonlinearity, the anisotropy of rubber-cord composites, the nonlinear boundary conditions from tire-rim contact and tire-pavement contact. The model can be used to simulate the changes of a rolling tire and calculate the tire deformation for various operating conditions. The profile of inflated tire is studied experimentally and numerically. The simulation result is in good agreement with the test result. Some contact problems, such as the tire deformation, the shape of contact area, the contact pressure distribution, are discussed in detail.

SCOPUS: ar.j, info:eu-repo/semantics/published

The purpose of the current study was to investigate the effects of different wheel sizes, with fixed gear ratios, on maximal effort mobility performance in wheelchair athletes. 13 highly trained wheelchair basketball players, grouped by classification level, performed a battery of 3 field tests in an adjustable wheelchair with 3 different wheel sizes (0.59 m, 0.61 m and 0.65 m). Performance was assessed using the time taken to perform drills, with velocity and acceleration data also collected via a wheelchair velocometer. 20 m sprint time improved in the 0.65 m condition (5.58 +/- 0.43 s, P = 0.029) compared with 0.59 m (5.72 +/- 0.40 s). Acceleration performance over the first 2 (P = 0.299) and 3 (P = 0.145) pushes was not statistically influenced by wheel size. However, the peak velocities reached were greater in the 0.65 m condition (4.77 +/- 0.46 m.s(-1), P = 0.078, Effect Size [ES] = 0.63) compared with 0.59 m (4.61 +/- 0.40 m.s(-1)). Impact velocity, calculated as the change in velocity from the onset of a push to the following impact peak, to define coupling performance, was also significantly improved in 0.65 m wheels (0.14 +/- 0.14 m.s(-1), P = 0.006) than 0.59 m wheels (0.05 +/- 0.10 m.s(-1)). The time taken to complete the linear mobility (P = 0.630) and the agility drill (P = 0.505) were not affected by wheel size. Finally, no significant interactions existed between wheel size, classification and any performance measure. To conclude, larger 0.65 m wheels improved the maximal sprinting performance of highly trained wheelchair basketball players, without any negative effects on acceleration or manoeuvrability. Improvements in sprinting were attributed to a combination of the reduced drag forces experienced and improvements in coupling thought to be due to the lower angular velocities of the wheel/hand-rim when developing high wheelchair velocities in larger wheels.

Objective: To examine wheelchair athletes' perceptions of wheelchair configuration in relation to aspects of mobility performance.Methods: Nine elite wheelchair athletes from wheelchair basketball, wheelchair rugby and wheelchair tennis were interviewed using a semi-structured format. Interview transcripts were analysed using an Interpretative Phenomenological Analysis, whereby emergent themes with common connections were identified and clustered into 3 superordinate themes: (i) performance indicators; (ii) principal areas of wheelchair configuration; and (iii) supplementary areas of wheelchair configuration.Results: Participants revealed that stability was the most important contributor towards successful performance. Whilst there was some agreement amongst participants on how manipulating most areas of wheelchair configuration influenced performance, opinions were divided as to whether camber had a positive or negative effect on straight line performance.Conclusion: Experienced athletes seemed to display a good understanding of how modifying wheelchair configurations can affect sports performance, yet the methods offered for identifying optimal settings were extremely subjective. Therefore, future quantitative research into specific areas of configuration is imperative to identify these optimums and to inform athletes about the decisions they make when configuring a new sports wheelchair.

Accurate camber prediction in prestressed concrete bridge beams is important to all parties involved in bridge design and construction. Many current prestress loss prediction methods, necessary for proper camber calculation, were developed many years ago and are predicated on assumptions that may no longer be valid as higher strength concrete, wider beam spacing, and longer span lengths become more commonplace. This throws into question which models are appropriate for use in camber calculation by the bridge engineers and contractors of today. Twenty-seven high-strength concrete modified 79 in. Bulb Tee beams with a design compressive strength of 9,000 psi were periodically measured to determine camber growth. Most available models for concrete creep and shrinkage were used to calculate creep and shrinkage strain. The modulus of elasticity equation of each model was used to predict modulus of elasticity of the studied mix. The Shams and Kahn compressive strength and modulus of elasticity equations were modified in order to approximate measured modulus of elasticity. The creep, shrinkage, and modulus of elasticity equations were used as inputs to an incremental time step method. The time-dependent change in beam curvature calculated by the time step method was used to calculate theoretical camber using the Moment-Area method. Predicted camber, using inputs from each considered model, was then compared with measured camber to determine the most accurate camber prediction models. Season of casting was also examined to determine what, if any, affect ambient temperature has on camber growth. For the studied beams, the Shams and Kahn Model for creep, shrinkage, and modulus of elasticity, used as inputs for an incremental time step analysis, were found to most accurately predict camber values. Lower concrete compressive strength was observed for test cylinders from beams cast in summer versus beams cast in winter. Differences in beam deflection based on season of casting showed mixed results. Master of Science

Prestressed concrete structural members camber upwards or downwards depending upon the location of application of prestress force. Identical members do not camber equally due to variability of the factors influencing it. Differential camber in the beams, if significant, results in excessively tall haunches or girder top flange extending into the bottom of the slab. For adjacent members like deck bulb-tees and box girders that are to be transversely post-tensioned the differential camber causes problems during the fit up process. This variation is undesirable and hinders the smooth progress of construction work if not properly accounted for at the design stage. Various factors influence camber and camber growth in prestressed members. Some of the factors are concrete strength and modulus, concrete creep and shrinkage properties, curing conditions, maturity of concrete at release of prestress force, initial strand stress, climatic conditions in storage and length of time in storage. Combinations of these variables result in variation of camber of otherwise similar beams at the time they are erected. One way to increase the precision of camber estimation is to use Monte Carlo simulation based upon the randomized parameters affecting the camber and camber growth. In this method, the parameters, in the form of a probability distribution function, are combined and passed through a deterministic model resulting in camber and camber growth prediction with narrowed probability bounds as compared to single definite value given by most contemporary methods. This outcome gives the expected range of cambers for a given girder design. After determining the expected range of camber, the ultimate goal is to provide guidelines for using unbonded monostrands for camber adjustment. Master of Science

The objective of this research was to determine if differential camber of prestressed concrete girders could be reduced by accurate prediction of initial camber at release of prestress. Maturity at prestress transfer was used to calculate modulus of elasticity for predicting camber at release. The research consists of a literature review of maturity methods, testing of a standard concrete mix to determine strength and modulus functions and measurement of girder camber and maturity. Both the Nurse-Saul and the Arrhenius maturity models were evaluated. Maturity relationships were developed for concrete mixes containing Type II and Type III cements. A relationship of modulus as a function of maturity was developed. Seven girders were tested. Camber predictions within 0 to ¼ in. of actual camber were obtained using modulus of elasticity calculated from a maturity based function. Comparison was made between maturity based modulus and standard strength based modulus models. Camber predictions based on modulus calculated based on field cured cylinder strengths were within 0 to ½ in. Master of Science

SCOPUS: re.j, info:eu-repo/semantics/published