ass日本风韵熟妇pics男人扒开女人屁屁桶到爽|扒开胸露出奶头亲吻视频|邻居少妇的诱惑|人人妻在线播放|日日摸夜夜摸狠狠摸婷婷|制服 丝袜 人妻|激情熟妇中文字幕|看黄色欧美特一级|日本av人妻系列|高潮对白av,丰满岳妇乱熟妇之荡,日本丰满熟妇乱又伦,日韩欧美一区二区三区在线

A mathematical model of 3-D random road surface was established based on the basic principles of harmonic superposition and triangulated irregular network. A rigid flexible coupling multi-body dynamic model of a heavy truck was established by using SIMPACK software, which included front suspension, rear balance suspension, steering system, tire system, etc. The tires and leaf springs were treated as deformable body, and rubber pads and limit block were reduced to force elements with non-linear stiffness and damping characteristics. Then a ride dynamic model of heavy vehicle was established，which combined virtual prototype vehicle with 3-D random road surface model by using SIMPACK software. The dynamic load coefficient and 95 percentage fourth power aggregate forces were used as the road-friendliness criterions for analyzing the road friendliness of heavy vehicles with different speed. Simulation results indicated that, when the vehicle drove on the B- and C-grade 3-D random road at the speed of 60~90km/h, the road friendliness of mid-axle and rear-axle reduced as the vehicle speed increased. The road friendliness of front-axle didn’t increase as the vehicle speed increased. When the vehicle speed surpassed 80km/h, the road friendliness of front-axle began to decrease. The road friendliness of the vehicle reduced as the vehicle speed increased. The road friendliness of B-grade road reduced by a big margin, while the road friendliness of C-grade road reduced by a small margin.