The influence of mechanical action on felting shrinkage of wool fabric in the tumble dryer

Felting shrinkage of untreated wool fabric occurs easily during tumble drying. Mechanical action applied on fabrics plays a significant part in felting shrinkage of wool fabric. In general, the more severe the mechanical action of a washing or drying machine, the more rapid the felting shrinkage. However, both the degree and type of mechanical action applied on the fabric can influence felting shrinkage of untreated wool fabric. In the current study, fabric movement and felting shrinkage of untreated wool fabric at different rotation speeds of the drum in a tumble dryer without heating were studied. Based on the different fabric movements at different rotation speeds of the tumble drum, the extents of impact and rubbing forces at different rotation speeds were assessed by ranking. The total mechanical action applied on the fabric was expressed as the percentage of thread removal of “thread removal fabric” during the drying process. The results showed that lowest mechanical force on fabrics could be achieved when higher rotation speeds of the drum were used to dry wool fabrics in the tumble dryer, and could prevent wool felting shrinkage. It was also found that falling of the fabric followed by impact on the drum wall caused less felting shrinkage than sliding with rubbing between fabrics. Therefore, maintaining the falling movement could be a potential method to dry wool fabric in drying machines without causing severe felting shrinkage.

Study on Looseness and Impact - Rub Coupling Faults of a Vertical Dual-Disk Cantilever Rotor- Bearing System

Because of wrong setting or long-term running of rotating machinery, the looseness may ouur in the bearing seats or bases. And also bring impact and rubbing of rotor-stator, That is the looseness and rub-impact coupling fault. In the paper,a mechanics model and a finite element model of a vertical dual-disk cantilever rotor- bearing system with coupling faults of looseness and rub-impact are set up. Based on the nonlinear finite element method and contact theory, the dynamical characteristices of the system under the influence of the looseness rigidity and impact-rub clearance is studied. The results show that the impact-rub of rotor-stator can reduce the low frequency vibration caused by looseness, and the impact-rub caused by looseness has obvious orientation. Also, the conclusion of diagnosing the looseness and rub-impact coupling faults is given in the end of the paper.