Study On Mobility And Durability Test Of Off-Road Vehicle

The off-road vehicle mobility and the vehicle durability are more demanded with the science and technology developing. The vehicle mobility is that the vehicle is able to self-identify the road feature and adjusts the self-control pattern based on the new vehicle techniques application, which makes the vehicle fast traverse the road segment. On the other side, the vehicle costumers demand more safety of the vehicle with the lightweight of automobile been applying. So the study of the vehicle durability shows very important.The main achievements of this dissertation are:1. The method based on on-line monitoring the vehicle running status is put forward. Real-time monitoring the vehicle suspension displacement and the vehicle running status, the roughness of the road surface is calculated in order that the vehicle is able to self-identify the road roughness. The vehicle speed and the longitudinal vibration acceleration are collected, aiming at identifying the terrain slope. The state of the vehicle and engine is recorded. The rolling resistance coefficient is computed, based on the output torque of the engine. Comparing this coefficient with the threshold of the soft road surface, the soft road surface could be identified. On the basis of the identification result of the road feature, the vehicle running mode could be adjusted, improving the mobility of the off-road vehicle.2. The ’human-vehicle body-wheel’, three-degrees-of-freedom vibration model is built. The driver’s vertical acceleration sequence signal on the roughness roads is acquired. The absorbed power is calculated based on human tolerance limit. And road roughness sequence signals by the inverse Fourier transform is worked out, which is the input of the simulation. Then the driver’s vertical acceleration sequence signal on the roughness roads is simulated utilizing the Simulink software. The speed at six-watts of absorbed power shows the mobility of the off-road vehicle passing through the roughness roads. Specific evaluation method is put forward for the different type off-road. At last, the synthetical velocity of the mobility of the off-road vehicle is calculated according to the weight coefficients of the different off-road.3. According to the damage of PG being equal to the customer’s, the vehicle durability test regulation is made. All relevant data of the customers’ vehicle and PG one is recorded by a transducer on vehicle. The fatigue load spectrum matrix is calculated by the rain flow counting method, and then the causing false damage is worked out. The per cent of miles on different roads and the different users’ cargo loads are surveyed. According to the acquisition signal and the customer survey, the customers’ road fatigue damage is simulated based on the Monte Carlo method. And 90% of the customer’s vehicle fatigue load spectrum (the rain-flow matrix) is confirmed. Comparing coefficients from the load spectrum of PG damage with that of usage damage, we finally determine the experimental conditions of the PG strengthening roads and test miles and test speed. The result that suggested our method is able to predict the vehicle bearing structure potential failure exactly, and to shorten the test mileage and the product development cycle effectively.On the side, the vehicle durability test procedure of Yi PG (Proving Ground) is built by choosing the suitable strengthen road, through measuring the load of the two different strengthen road the Yi PG, referenced on the Jia PG procedure which has been built before. The time serials’ load of Yi’s and Jia’s PG one is recorded by a transducer on vehicle. The PG road roughness is calculated. And the relationship of the output of the vehicle response with the input of the road excitation is studied according to the vehicle spectrum. The pseudo damage of the vehicle on PG road is calculated according to S-N function. And then theirs damage distribution diagrams are compared. The suitable strengthen road is chosed as the test road of the vehicle durability test procedure of Yi PG.