Wear Of Rods Research Articles

On Nonlinear Vibration and Fretting Wear of Nuclear Fuel Rods Influenced by Coolant Cross-flow

The paper deals with mathematical modelling of nuclear fuel rod (FR) vibration in TVSA-T fuel assembly induced by pressure pulsations of coolant. The FR is modelled as a system consisting of two subsystems - fuel rod cladding and fuel pellets stack - that can possibly impact-interact. Besides, the cladding subsystem can possibly loose contact with spacer grid cells that is another source of strong mechanical nonlinearities. The contact forces in all the contact points are represented by the force-velocity-displacement characteristics that include both normal and friction forces. The influence of coolant cross-flow is analysed using partitioned approach to fluid-structure interaction description. The qualitative change of FRs motion and the change of fretting wear of the FR cladding are shown.

Wear characteristics of polished and glazed lithium disilicate ceramics opposed to three ceramic materials.

This study compared the wear characteristics of a heat-pressed lithium disilicate ceramic material opposed to feldspathic porcelain, a lithium disilicate glass ceramic, and zirconia materials. Ceramic plate specimens were prepared from feldspathic porcelain (EX-3 nA1B), lithium disilicate glass ceramics (e.max CAD MO1/C14), and zirconia (Katana KT 10) and then ground or polished. Rounded rod specimens were fabricated from heat-pressed lithium disilicate glass ceramic (e.max press LT A3) and then glazed or polished. A sliding wear testing apparatus was used for wear testing. Wear of glazed rods was greater than that of polished rods when they were abraded with ground zirconia, ground porcelain, polished porcelain, or polished lithium disilicate ceramics. For both glazed and polished rods, wear was greater when the rods were abraded with ground plates. The findings indicate that application of a polished surface rather than a glazed surface is recommended for single restorations made of heat-pressed lithium disilicate material. In addition, care must be taken when polishing opposing materials, especially those used in occlusal contact areas. (J Oral Sci 58, 117-123, 2016).

Effect of Flow Characteristics of Polymer Flooding Produced Liquid on Attrition of Sucker Rob and Tube

Because of complex flow characteristics, polymer flooding produced liquid can bring many problems such as serious eccentric wear of rod and tube, breaking and divorcing of rod, and shortened cycle of pump-check. Flow resistance experiment was carried out aimed at these problems. Experimental results show that on-way resistance that sucker rod acts on polymer flooding produced liquid mainly depends on the viscosity of liquid and its elasticity can be ignored; Local resistance caused by couplers and centralizers is mainly related to the velocity of produced liquid, while the effect brought by mass concentration can be neglected; Resistance that pump valve endued and rate of flow agree to the exponential law; Total resistance of pump valves is generated mainly by down-valve and the law of resistance that water and polymer solution act on valves are similar. The problems that eccentric wear of rods and tubes is serious and the cycle of pump-check is shortened are not completely caused by up stress increasing after polymer flooding.

Cyclic oxidation and wear of tungsten rods in contact with glass in atmospheric air

Tungsten tools used in the glass-forming industry undergo complex damage process resulting from cyclic contact with molten glass and atmospheric air and from friction between glass and tungsten. The damage process involving oxide scale growth and wear has been studied on W rods of two different diameters, in contact or not with glass, with different friction velocities. Damage is characterized quantitatively and the contributions of oxidation, borosilicate glass–tungsten reaction, and wear are discussed.

Transient wear of silicon nitride in lubricated rolling contact

Wear of silicon nitride balls and rods was studied in lubricated rolling contact using a ball-on-rod rolling contact fatigue (RCF) tester. The wear response of both the elements, balls and rods, was transient. The nature of the transient was dependent on the initial surface roughness of the rod, while the total volume loss increased with the initial contact stress. Bearing-grade balls ( R a=0.005 μm) rolling on as-ground ( R a=0.18 μm) rods produced a high initial wear rate in both elements that decreased exponentially with time or number of loading cycles. Improving the surface finish on the rods by lapping ( R a=0.05 μm) produced delayed wear in both elements; i.e., the wear rate was initially zero during an incubation period, then, increased and, finally, decreased. The role of decreasing contact stress in the transient wear, and the micromechanisms of wear involving a tribochemical reaction are discussed.

Reciprocating-sliding wear of sucker rods and production tubing in deviated oil wells

Sucker rod and tubing strings in highly deviated oil wells are subject to severe impacting and sliding wear as they interact during cyclic pumping operations. A large-scale wear test machine with multiple test cells has been designed and manufactured to test actual tubing, rod and coupling specimens under simulated operating conditions. In addition, tests are also performed in a small-scale wear test rig. The effects of stroke rate, contact load and wellbore fluid on wear rates of sucker rod/production tubing components are studied. Test results have shown that the stroke rate and contact load influence the transition from mild to severe wear. A field study program has been undertaken in parallel with the laboratory wear study to determine the variety and extent of production wear problems.