Quantification of 6-Degree-of-Freedom Chassis Whole-Body Vibration in Mobile Heavy Vehicles Used in the Steel Making Industry

Abstract

Whole-body vibration (WBV) of mobile machines used in the steel making industry has not previously been quantified in six-degrees-of-freedom (6DOF). The purpose of this paper was to quantify 6DOF vibrations during the daily operating tasks of 5 commonly used mobile machines types used in the steel making and metal smelting industries. Vibration data were recorded from the chassis of five commonly used mobile machines using a MEMSense MAG3 triaxial accelerometer & gyroscope (MEMSense, SD, USA), and analyzed using custom MatlabTM code. Elevated values were observed at the chassis for crest factors, peak running root mean squared accelerations, and vibration total values, resulting in ISO 2631-1 (1997) comfort predictions ranging from Uncomfortable to Extremely Uncomfortable. Vibration dominant frequencies were generally between 1 and 8Hz. A second peak which occurred at approximately 27 Hz was observed for each vehicle in almost all axes. Occurring at a frequency that has the potential to produce negative health effects, this second peak was probably caused by the engine idling or running at low speeds. Field vibration profiles from this study have been used as inputs to a 6DOF robot for use in a corresponding laboratory study designed to optimize seat selection thus allowing the steel making and other similar industries to select operator seats based on industry specific field vibration characteristics.

Reducing whole-body vibration through field vibration tested heavy equipment seat retrofitting

“…In our phase one field data collection, VTV values for slag pot haulers ranged between 1.7-2.6 m/s 2 [15,16] whereas in the current work, the slag pot hauler with the new seat installed ranged between a minimum of 0.356 and a maximum of 0.956 m/s 2 which was an improvement. The slag pot hauler comfort levels from our previous field study placed in the top two categories of discomfort (Very Uncomfortable and Extremely Uncomfortable) [15,16] whereas the slag pot hauler with the new seat installed placed in the second lowest discomfort rating (Fairly Uncomfortable).…”

“…Results from the field and the laboratory studies have been reported previously [15][16][17]. For the current phase, the vibration results are presented in Table 2 while the Seating Questionnaire results are contained in Table 3.…”

“…The first involved 6-DOF chassis acceleration data recorded for five types of mobile machines from the steel making industry [15,16]. Following field data collection, six, 20 second representative field profiles were assembled from the 'worst' WBV machine for use in the second phase which was conducted in the laboratory [17].…”

“…Results from the first project phase showed that 6-DOF vibration chassis data recorded from mobile machines in the steel making industry resulted in ISO 2631-1 (1997) [3] comfort predictions ranging from Uncomfortable to Extremely Uncomfortable [15]. It was also revealed that six of eleven tested machines had tri-axial seat vibration dose values above the health guidance caution zone (HGCZ) [16].…”

“…This allowed for a controlled testing environment to determine an optimal seat to best attenuate vibration profiles associated with steel manufacturing mobile equipment operation. At the conclusion of phase two, a seat was identified to be retrofitted in the mobile equipment type previously found to expose steel manufacturing mobile machine operators to the highest levels of WBV [15,16]. The purpose of the current paper is to report on the third project phase which was designed to assess the WBV attenuation effectiveness of the retrofitted seat under field operating conditions.…”