Excessive Wear Mechanism due to Wheel/Rail Contact in Curve Railway Track
Railway is the mass transport system that most used to carry passenger or commodity. In the city, most of railway used as passenger car whereas in mining most of them as freight car. The main problem in railway field is high of wear rate due to increasing of the capacity needed. It will cause the reliability and availability of facilities and infrastructure decrease, even increasing the derailment accident and operational cost. In 2007, the Department of Transportation has allocated Rp 160 billion to repair the tracks in South Sumatra covering 70 km along the vulnerable point between Tanah Tinggi until Lubuklinggau. In the year 2000-2004, the proposed cost of infrastructure maintenance and reliable infrastructure valued at Rp 11,835 Trillion. Most of these costs are for repairs due to wear and failure. In this research, the mechanism of excessive will be investigated.
Several attempts to reduce the wear rate have been done but the wear rate is still high. Some effort to reduce this problem: wheel rail profile optimization, material improvement, smoothing the contact surface, using lubrication, expanded curvature track radius, and by mean of layer. In case of Babaranjang train has been completed i.e: utilizing worn wheel profile, enlarge clearance between wheel flange and flange face of the rail in Rotary Car Damper I, in 2001 the worn wheel profile and set up the rubber seat between frame adapter and side frame bogie have been tested. The set up of rubber seat has been intended to make the wheelset have yaw movement easier. Good result is determined and wear rate can be reduced. Furthermore, optimization wheel profile has been investigated in 2007. This new profile accord with the UIC 54 rail profile type. This profile can elongate life time about 13% and reducing contact pressure about 9%.
To overcome the excessive wear is performed model analysis and experimental to observe wear mechanism. Start from the multi dynamic model of railway vehicle, followed by wheel rail contact modeling then continued by wear modeling. Based on these steps, the whole wear model in wheel and rail can be founded. Subsequently, twin disc test is carried out to observe the excessive wear phenomena in wheel and rail. Thereby, main factor of excessive wear rate can be discovered. In the future the method to diminish wear rate by minimization effect of this factor. The outcome of reducing wear rate decrease derailment accident and the model can be utilized by Railway Company to minimize maintenance cost.
In the dynamic analysis obtained the contact pressure distribution at the time the vehicle passed the curve track. In the initial track contact occurs only on the tread rail. Furthermore, due to the movement of snake motion of vehicle then contacts on the flange started happening. In curve track, contacts will occur at two points namely at the tread and the flange section. On the occurrence of contact is the most high wear rate.
Tread contact on the rail to the right side is always greater than the left side of the tracks. This is due to absence of contact that occurs on the flange, thus concentrated load is only at the tread alone and wheel on right side are always in contact with the rail flange.
Contact pressure obtained in dynamic analysis is used as a pressure design in twin disc design. This pressure will also be used as the operational pressure on the mechanism of wear testing. Stress distribution on the cross section rails is also obtained by using FEA as well as with the pressure distribution in the contact area. A shown on draft paper attached the pressure distribution like an ellip is closed to the teoritical of contact theory.
This study has obtained contact pressure behavior when the vehicle through the curve track and the contact stress distribution and pressure. Later, in the experiment will get the wear mechanism that occur in the contact wheel and rail. Curving speed will increase pressure contact on the flange side. In this study, the pressure is increased by 16.8% for the high rail or left wheels on the leading wheelset of front bogie and by 15.7% in the left wheels on the rear wheelset. While in the tread contact the increasing of speed does not necessarily improve the contact pressure but will produce a contact pressure which the wheel-rail contact pressure on the right side is higher than on the left. Finite Element Method (FEM) can show the contact stress distribution and the influence of contact at a certain depth. The results showed that the calculation of the contact dimensions and maximum contact pressure give more conform results. The difference results obtained by the method of Hertz are between 1.47-2.37% for the maximum contact pressure and 2.45-3.02% for the major axis the ellipse. The difference results using finite element method also gives conform results of 0.09-3.5% for the maximum contact pressure.
LIST OF RESEARCH OUTPUT
- Parwata Md, I GN Wiratmaja Puja, Bagus Budiwantoro, Satryo S. Brodjonegoro, (2010): Contact Pressure Behavior Due to Wheel and Rail Contact in Curve Track, Proceeding The 4th Indonesia Japan Joint Scientific Symposium, Bali, 1, 46.
- Draft Paper: Penyelesaian Pendekatan Problem Kontak Hertzian Pada Kasus Kontak Antara Roda dan Rel
Twin Disc Testing Tools
Figure 1. Babaranjang Train in South Sumatera
Figure 2. Contacts between the wheels with the rails
Figure 3. Bend location with highest wear rate in Tarahan
Figure 4. Rails cutting for test specimens
Figure 5. Component test equipment that will be assembled
HEAD OF RESEARCH TEAM: Dr. Bagus Budiwantoro
TEAM MEMBERS: Prof. Dr. Ir. IGN Wiratmaja Puja, Prof. Dr. Ir. DJ. Schipper, I Made Parwata, ST., MT.
OFFICIAL ADDRESS: PT. Kereta Api Indonesia, PT. INKA, Email: email@example.com