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Technical Paper

Propagation of Error Applied to Linear Vehicle Dynamics

This paper applies basic statistics to the simulation of vehicle dynamics in the time domain and the frequency domain. The methods presented here yield an expectation for the variation of the computed results as a function of variation in input parameters. Applications include important steady state measures of vehicle performance such as understeer gradient and yaw rate gain. Follow up analysis includes measures of transient response in the time domain and of amplitude and phase relationships in the frequency domain. There are several potential applications for this methodology, perhaps most important, an understanding of the consequences of parameter uncertainty on the credibility of simulated results.
Technical Paper

Multiple Steered Axles for Reducing the Rollover Risks of Heavy Articulated Trucks

This paper presents an analytical study of the performance improvements that can be obtained at both high and low speed using multiple steered axles on heavy articulated trucks. At high speed, rollover usually represents a worst case scenario. Therefore we have chosen to evaluate possible steering designs based on their ability to reduce lateral acceleration of the semitrailer center of gravity. This is in contrast to passenger cars where four-wheel steering has typically been evaluated based on measures that were thought to be related to driver acceptance. This paper also investigates the effects of steering rear tractor axles on the low-speed maneuverability of the vehicle. Steering algorithms for the rear tractor tires were evaluated using frequency response and simulation of an obstacle avoidance maneuver. Results indicate that at high speeds considerable reductions in trailer lateral acceleration can be obtained during transient maneuvers.
Technical Paper

An Experimental Study to Evaluate the Droplet Impinging Erosion Characteristics of an Icephobic, Elastic Soft Surface

Elastic soft material/surface, such as Polydimethylsiloxane (PDMS), is a perspective, useful and low-cost hydrophobic and icephobic coating. While it has been reported to have good mechanical durability, its erosion durability under the high impacting of water droplets pertinent to aircraft inflight icing phenomena has not been explored. In this study, the droplet imping erosion characteristics of an icephobic PDMS surface/material is evaluated systematically upon the dynamic impinging of water droplets at different impact velocities (~ up to 75m/s), in comparison with other state-of-the-art icephobic materials/surfaces, such as superhydrophobic surface (SHS) and slippery liquid-infused porous surface (SLIPS). Surprisingly, the contact angle (CA) of the elastic PDMS is shown to have an over 20° increase (from 105° to 128°), which represents better hydrophobicity, after the erosion test which is mainly contributed to the higher roughness of the eroded PDMS surface.
Technical Paper

An Experimental Investigation of a Wind-Driven Water Droplet over the Slippery Liquid Infused Porous Surface

The promising anti-icing performance of the slippery liquid infused porous surface (SLIPS) has been recently demonstrated for various engineering applications. The runback icing for aircraft and wind turbines could be effectively mitigated considering the timely removal of water droplet by the wind shearing force due to the low adhesion on the SLIPS. In this study, the flow field both inside and around the wind-driven droplet over the SLIPS was experimentally investigated by using Particle Image Velocimetry (PIV) technique. Previous studies majorly focus on the internal flow pattern before the droplet incipient motion. In this study, the flow field inside a moving droplet was firstly investigated. As a result of the low surface adhesion of the SLIPS, droplet oscillations were eliminated and the droplet internal flow field could be corrected from the optical distortion.
Technical Paper

A Novel Heating-Coating Hybrid Strategy for Wind Turbine Icing Mitigation

The electro-thermal method is most commonly used for wind turbine anti-/de-icing. The upmost drawback of such systems is the high power consumption. In the present study, we proposed to use a durable slippery liquid-infused porous surface (SLIPS) to effectively reduce the power requirement of the heating element during the anti-/de-icing process. The explorative study was conducted in the Icing Research Tunnel at Iowa State University (ISU-IRT) with a DU91-W2-250 wind turbine blade model exposed under severe icing conditions. During the experiments, while a high-speed imaging system was used to record the dynamic ice accretion process, an infrared (IR) thermal imaging system was also utilized to achieve the simultaneous surface temperature measurements over the test model.