ㆍ Product: Packaged freight
ㆍ Analysis Goal: Effect of road roughness to accumulated fatigue of package freight in transportation by truck
In the transportation of packaged freight by truck, the magnitude of damage depends largely on the roughness of the road.
Because the road surface shape is complex, it is often expressed by the power spectrum density of a typical road surface height. Damage is expressed in accumulated fatigue. However, the relationship between damage and the road surface shape is not clear. Here, a computational analysis of a truck loaded with packaged freight driving over a road is performed using RecurDyn.
The road surface shape is based on the theory of non-Gaussian distribution that was created from the power spectrum density of the surface height set by the Japanese Industrial Standards (JIS). Kurtosis was used as an index to indicate the road surface roughness, and the relationship between the kurtosis and the accumulated fatigue obtained from the vibration acceleration of the packaged freight on the truck was analyzed.
① Create RecurDyn model of typical package transportation truck.
② Generate non-Gaussian random road profile in ProcessNet from a road height PSD in JIS standard.
③ Create road file for GRoad from that random road profile.
④ Perform driving simulation of truck using the above conditions.
⑤ Calculate accumulated fatigue of the packaged freight.
⑥ Perform statistical analysis.
Key Technologies for Analysis
• Truck model for driving simulation on 3D road
• Tire model for driving simulation on 3D road
• Road model for driving simulation on 3D road
• 3D road profile in GRoad generated using random vibration theory
• Statistical analysis between Kurtosis of road profile and accumulated fatigue of freight acceleration
• Damage evaluation of packaged freight in transportation relies on simulating bench tests because of difficulty of using actual driving tests.
• JIS provides road roughness in frequency domain but no actual shape is provided.
• The relationship between the fatigue of packaged freight and the road surface is not clear.
• Road profile is created based on non-Gaussian random vibration theory (1) programmed into RecurDyn/ProcessNet .
• Truck driving simulation model is created with GTire in RecurDyn/Tire and UATire.
• Accumulated fatigue for damage is calculated from zero-cross-peak count (2) of package acceleration on truck and studied in relation with kurtosis of road profile.
(1) A.Hosoyama, K.Saito, T.Nakajima. Non-Gaussian random vibrations using kurtosis, Proceedings of 18th IAPRI World Packaging Conference, San Louis Obispo (CA), USA, pp 35-40 (2012)
(2) zero-cross-peak count (ISO 16750-3_2007)
• Road model for driving simulation in RecurDyn can be generated from arbitrary road properties in frequency domain.
• Various road profiles of different kurtosis can be defined from one PSD road specification.
• It is now possible to estimate quantitative damage β from road profile kurtosis.