公路液罐车液固耦合机理与防侧翻控制研究

Road liquid-filled tractor-semitrailers tend to rollover easily, and that mechanism is not clear due to its high mass-center, large amplitude of nonlinear violent sloshing of liquid within the tank, the effect of the liquid-tank coupling interaction and fluid-vehicle coupling motion. The present studies will focus on 5 tasks as follow. Task 1 is setting up a numerical model of the liquid sloshing dynamics (NMLSD) in partially filled tanks based on investigation of the internal mechanism and dynamic behavior of fluid-structure coupling interaction,and in addition, the complicated liquid-filled tractor-semitrailer dynamic model is then bulit up by coupling the NMLSD and the estabilished complicated tractor-semitrailer dynamic model. Task 2 is numerically simulating and analyzing the following by using NMLSD and the complicated coupling model: the dynamic response of liquid sloshing under different external excitations, especially the influence on the slosh impulse forces and moments, the contributions of the vortex forces and the nonlinear dynamic behavior of the system to liquid sloshing, and the modal parameters of the liquid slosh and the roll stability character of tank vehicles will also be studied. Task 3 is that an equivalent nonlinear structural vibration system contains of multiple bodies and multiple degrees of freedom of the sloshing liquid is built based on the energy equivalent principle and the results of the modal studies of liquid sloshing, and a simple dynamic model of road liquid-filled tractor-semitrailers is integrated by the liquid equivalent vibration model and the established simplified tractor-semitrailer dynamic model. With the simplified tank vehicle dynamic model, tank vehicle parameters and states estimation algorithm and Rollover dynamic warning algorithm are investigated. Based on the above, task 4 is that the rollover warning based active anti-roll control algorithms are investigated for the liquid-filled tractor-semitrailer. Task 5 is that the co-simulation model and the anti-roll control algorithm are validated by both the scale tank hardware-in-the-loop test bed and the vehicle field test, in which the HIL test bed consists of the electronic brake system, the 6 DOF motion plate and the scale tank. The results of this study will provide the theoretical basis of the tank vehicle design and the active safety control.

公路用半挂式液罐车具有重心高、液体晃动大且强非线性、液-罐耦合、液体晃动与车辆运动耦合等特点，使其易发生侧翻且机理不清。本项目通过研究半挂式液罐车液-固耦合内在机理，建立液固耦合二相流液体晃动动力数值模型和半挂车动力学模型结合的双向耦合模型；分析液体在复杂外部激励下动态响应过程，考察液体晃动产生的冲击力/力矩，涡动力及系统非线性动态特性等对液体晃动的贡献、液体晃动模态参数和液罐车侧翻稳定性；依据能量等效原则，建立液体晃动系统的等效多质量多自由度非线性结构模型，与已建立半挂车动力学仿真模型联合，得到简化半挂式液罐车动力学模型，进行状态估计和预警；研究基于预警机制的半挂式液罐车主动防侧翻控制算法；将运动平台、缩比液罐与商用车电控制动系统的硬件在环试验台相结合，对液固耦合特性、动力学模型、预警和防侧倾控制算法进行试验台验证和实车试验验证。本项目将为我国公路液罐车主动安全的提高奠定理论基础。

公路用半挂式液罐车具有重心高、液体晃动大且强非线性、液-罐耦合、液体晃动与车辆运动耦合等特点，使其易发生侧翻且机理不清。本项目采用Fluent软件建立了液固耦合二相流液体晃动动力数值模型，采用TruckSim软件建立了半挂车动力学模型，并实现了液体晃动与半挂车动力学相结合的双向耦合模型。利用建立的半挂式液罐车双向耦合动力学模型，进行半挂式液罐车侧翻稳定性分析，系统研究侧翻稳定性影响因素，并进行侧倾稳定性影响的灵敏度分析，考察液体晃动产生的冲击力/力矩，涡动力及系统非线性动态特性等对液体晃动的贡献、液体晃动模态参数和液罐车侧翻稳定性，探究半挂式液罐车的当前运动状态、驾驶员操作（制动、转向等）、路面坡度不平度等因素与侧翻稳定性的关系，分析产生侧翻的原因。依据能量等效原则，建立液体晃动系统的等效刚体模型、准静态液体模型、等效单摆模型，与已建立半挂车动力学仿真模型联合，得到简化半挂式液罐车动力学模型。针对液体晃动导致液罐车响应波动且易侧翻的特点，综合考虑液罐车的液体晃动抑制、横摆稳定性和侧倾稳定性控制，基于ESC系统开发了液罐车横摆-抑晃-防侧翻集成控制策略。对于车辆操纵不太稳定，但尚未进入侧倾不稳定状态的过渡区域，开发了以液罐车辆的横摆、侧偏和液体的等效摆角跟随期望值为控制目标的LQR横摆抑晃控制方法，推迟进入防侧翻控制的时机；针对临近侧翻的危险工况，开发了以尽量减少液罐车横向载荷转移率LTR为控制目标的LQR输出最优防侧翻控制方法；为了动态区分侧翻失稳紧急程度，防止误触发或过晚触发控制系统，开发了考虑液体晃动的侧翻预警时间TTR预警算法，并以TTR为切换指标，进行横摆抑晃控制模式和防侧翻控制模式的切换。开发了液罐车硬件在环仿真试验平台和缩比液罐实车试验平台。对液体晃动动力数值模型、半挂式液罐车防侧翻控制算法与控制逻辑进行了试验台和实车验证。本项目的研究成果为我国公路液罐车主动安全的提高奠定理论基础。