Summarize all the loads described in class and quantitativel

Summarize all the loads described in class and quantitatively describe their effect on vehicle properties (acceleration, braking, fuel consumption). Please include the scenarios discussed. (See Chapter 5 in Overview)

Solution

Various Loads Acting on the vehicle :-

Effects :-

DYNAMIC EFFECTS

The axle load of a heavy vehicle is not steady but it varies because the road is not even. This variation may easily be +/- 20 percent which means that the axle load varies between 80 kN and 120 kN if the nominal static axle load is 100 kN. Not only the unevenness of a road but also the quality of suspensions and the structure of the vehicle have effect on this dynamic axle load.

The main movements are the body bounce, specific frequency usually between 1.5 and 3 Hz and axle hop, specific frequency about 10 Hz. Body bounce is usually dominating. An example of dynamic axle loads is presented in Figure 4. The dynamic axle loads may concentrate on certain spots along a road or there exists spatial repeatability of dynamic loadings. If the same vehicle runs at the same speed the repeatability is nearly perfect. Relatively little is known by the present time about spatial repeatability of the whole vehicle fleet driving at different speeds on roads of different unevenness.

The dynamic axle loads depend on the evenness of the road and on the properties of suspensions and especially on dampers. Air suspensions have been usually thought to be better because they are good for the load (and passengers). The reality is not necessarily the same. If the damping is not adequate the stresses to the pavement may great. Thus at the present time it is not known very well what kind of suspensions are really \"road friendly\".

Effect of Passenger Load :-

Consumers may be unaware of the risk of rollover crashes posed by passenger loads in vehicles with poor roll stability. This analysis demonstrates that certain sports utility vehicles and small pickup trucks have designs that are so unstable that the weight of the passengers in the vehicle affects its propensity to roll over. This effect occurs even though the weight of the loaded vehicle is less than the manufacturer\'s gross vehicle weight rating. The risk of a fatal, \"untripped\" rollover crash in vehicles with low roll stability is increased as each passenger is added to the vehicle load.

Other Effects :-

Due to import of vehicle loads and speed in damage of pavement structure, the influence on vehicles and pavement with different loads and speeds are investigated by spot experiment. The experimental results show that the vertical vibration acceleration of each wheel grows with increase in running speed. At a fixed speed, the dynamic load effect of zero load and overload is obviously bigger than that of full load. At 60 km/h and 100 km/h, the rear wheel\'s normal loads under zero load is bigger than that under full load. The normal loads of wheels under overload increase compared with that under still load. At zero load, pavement displacement grows firstly and drops a litter bit with speed increasing, but it increase with speed increasing at full load and overload. Pavement displacement under zero load is bigger than under full load and overload at lower speed, but pavement displacement grows with vehicle load increasing at high speed.