Composites stay on track in rail applications

Composites stay on track in rail applications

R AILWAYS Composites stay on track in rail applications of this will be for railway or mass-transit use, but taking into account the greater importa...

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AILWAYS

Composites stay on track in rail applications of this will be for railway or mass-transit use, but taking into account the greater importance of these forms of t r a n s p o r t in Europe com pared to North America and the trend towards environmentally friendly forms of transport, the potential is considerable. The success of pul t ruded composites as the core material for the type of high voltage electrical insulators and allied components used for railway catenary and p a n to g ra p h construction was cited by the European Rail Research Institute. This, coupled to the superior fire performance made possible by the advent of phenolic resin systems capable of being processed by all composites fabricahile the total E u r o p e a n and North tion routes, has p r o m p t e d the Institute to American markets for composites examine further the potential for compoare not too dissimilar, (965 000 and sites. It is a major subject of its B 108 1 070 000 tonnes respectively in 1991), Specialist Committee, covering as secondary pultrusion continues to find wider recogni- structures: vehicle cabs and noses, linings, tion and more positive acceptance from the partitions, seats, etc. The Institute says th a t American user. Thermoset pultrusions have it is impressed with the low fire propagation j us t 2% of the E u r o p e a n composite market p o t e n t i a l and the related r e d u c e d h e a t c o m p a r e d with a share of 5.5% in the USA. If release, smoke and toxic fume characterisone assumes t h a t pultrusion has an average tics of the phenolics, irrespective of the m et hod of fabrication. While knowing of no 10% p e n e t r a t i o n in the t r a n s p o r t sector of work currently involving the application of the composites market, as suggested by one composites to heavily stressed railway comspeaker at the Lille conference, this gives a ponents such as bogie frames, it says th a t c o n s u m p t i o n of nearly 6000 tonnes for North such applications can now become reality if America and 2000 tonnes for Europe. Not all further development work is carried out. However, marked material transitions of this type, away from the traditional steel and | I aluminium, may also dem an d some drastic redesign of the system in which they are employed if the best, most cost-effective, use of the composite properties is to be ensured. That was the opinion reflected by several presentations. For exam pl e in his introduction, EPTA secretary, Jaap Ketel showed a particularly telling and p e r t i n e n t photograph. Based on its evidence he opined th a t a recent high-speed rail accident in the Netherlands might have been less severe had the catenary support pylons been of composite rat her than steel construction. Prototype versions have already proved th a t the feasibility of such. pylons is clearly enhanced by the use of phenolics. Several phenolic pul t rusi on exam p le s from both

C o m p o s i t e s are c o n t i n u i n g their s u c c e s s f u l penetration o f the railway, mass-transit and allied market sectors with c o m p o n e n t s for structural, electrical, rolling-stock, station and t u n n e l applications, increasingly employing the pultrustion process. Where fire retardant properties are required a p h e n o l i c resin matrix is often used. Trevor Starr o f T e c h n o l e x reports from the E u r o p e a n Pultrusion T e c h n o l o g y A s s o c i a t i o n ' s c o n f e r e n c e on C o m p o s i t e s in Railways, held in Lille, France.

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FIGURE 1: Composites are finding more applications in railways.

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REINFORCED PLASTICS FEBRUARY 1993

0034-3617/93/$3.50 ~

1993, Elsevier Science Publishers Ltd.

R AILWAYS FIGURE 2: Wavin's fibreglass jacket pipes under railway embankments.

A m e r i c a a n d E u r o p e w e r e on display. Most, like t h a t from P u l t r e x Ltd of C l a c t o n - o n - S e a , UK, a r e now m o v i n g s t e a d i l y f r o m developm e n t a n d p i l o t p r o d u c t i o n to full-scale c o m m e r c i a l i z a t i o n . They offer t h e d e s i g n e n g i n e e r g r e a t e r flexibility in t h e use of c o m p o s i t e s t h a n previously possible. Opening up c o m p o s i t e s to c o m p o n e n t s t h a t owing to tire p e r l b r m a n c e could not p r e v i o u s l y be m o u l d e d in this way. Pultruded glass-epoxy tension rods used as p e r m a n e n t a n c h o r bolts in t u n n e l s are effectively r e p l a c i n g the e a r l i e r steel v e r s i o n s i r r e s p e c t i v e of the m e t h o d of s e c u r i n g t h e m in place, w h e t h e r by m e c h a n i c a l locking m e m b e r s or the use of adhesive. They are m u c h m o r e r e s i s t a n t to t h e often aggressive e n v i r o n m e n t , a n d t h e y can be p r o d u c e d to highly c o n s i s t e n t d i m e n s i o n a l , physical a n d mechanical properties. Furthermore, the d i r e c t i o n a l i t y of the l a t t e r is all i m p o r t a n t to the a p p l i c a t i o n success a n d with t h e p r o b l e m of t h r e a d f o r m i n g resolved -- a n d a i d e d by the c o a r s e n a t u r e of t h a t t h r e a d -p u l l r u d e d t e n s i o n rods offer a n o t h e r distinct a d w m t a g e . This ~ o e of a n c h o r i n g often h a s to be r e m o v e d at s o m e stage. Neglecting t h e q u e s t i o n of c o r r o s i o n c a u s i n g p r o b l e m s w h e n the rod h a s to be r e m o v e d or replaced, t h e steel version by its very n a t u r e p r e s e n t s m o r e difficulties t h a n the p u l t r u d e d version. The c o m p o s i t e b r e a k s m o r e readily a c r o s s t h e grain of the fibre r e i n l b r c e m e n t . This is useful w h e n a s m a l l b o r e tunnel, p e r h a p s stabilized by this form of a n c h o r bolt, is t h e n wi
tunnelling and other equipment damage, a n d in c o m p a r i s o n w i t h steel, is a l s o quicker. The g r e a t e r cost of the c o m p o s i t e a n c h o r bolt is t h e r e f o r e of less c o n s e q u e n c e . Neglecting the fact t h a t legislation h a s forced the change, t h e r e are s i m i l a r gains in using f i l a m e n t w o u n d e p o x y fibreglass j a c k e t p i p e s u n d e r railway e m b a n k m e n t s . Since J a n u a r y 1991, t h e a s b e s t o s - c e m e n t p i p e s p r e v i o u s l y e m p l o y e d a r e no l o n g e r p e r m i t t e d by t h e D u t c h G o v e r n m e n t . T h e search for an alternative encompassed p r o p e r t i e s of w a t e r - t i g h t n e s s , s h o r t - t e r m t e m p e r a t u r e r e s i s t a n c e to 120~'C ( w h e n carrying high v o l t a g e c a b l e s ) , high c h e m i c a l / c o r r o s i o n - r e s i s t a n c e , an a b i l i t y to be m e c h a n i c a l l y p u s h e d into p l a c e w i t h o u t c o l l a p s e buckling, close d i m e n s i o n a l tolerance, an effective j o i n r i n g s y s t e m b e t w e e n individual s e c t i o n s up to 25 m long, an ability to s u s t a i n an i m p o s e d load (e.g. 1 MPa p r e s s u r e m i n i m u m ) , a n d last b u t not least a c o n s t r u c t i o n c a p a b l e of a c c u r a t e l y carrying t h e c u t t i n g - h e a d on t h e first section. With 600 m of this e n v i r o n m e n t a l l y safe a n d c o r r o s i o n - f r e e p i p e s y s t e m recently successfully installed in a m a j o r railway t u n n e l in R o t t e r d a m the m a n u f a c t u r e r , Wavin Repox, is n o w o f f e r i n g t h e s y s t e m t h r o u g h o u t Europe. The fact t h a t this s y s t e m is also n o w being offered for o t h e r t h a n t h e original railway embankment and tunnel requirements, f u r t h e r c o n f i r m s h o w t h e d e v e l o p m e n t of c o m p o s i t e s to a n s w e r one m a r k e t s e c t o r need is e v e r m o r e f r e q u e n t l y satisfying t h e n e e d s of a n o t h e r . •

REINFORCED PLASTICS FEBRUARY 1993