ABSTRACT
I n t h i s t h e s i s , an axisym m etric R a d i a l E x tru s io n prob
lem fo r ex tr u d in g tu b u la r components is a n a ly s e d . T h e o r e t ic a l a n a ly s e s a re made to p redict t h e average p r ess u r e in R a d ia l E x t r u s i o n . T h e o r e t i c a l analyses a re done u s in g the upper-bound method and S l a b method (S t r e s s - e q u ilib r iu m method) . For the
upper-bound a n a l y s is p a r a l l e l v e l o c i t y f i e l d is u s e d . T h e values o f a v erag e p r e s s u r e o b t a in e d from the upper-bound a n a ly s is and t h a t due to S l a b method o f a n a l y s is a r e q u i t e c l o s e . Experim ents a r e conducted to s u b s t a n t ia t e t h e t h e o r e t i c a l p r e d i c t i o n s .
U s in g a 2^ F a c t o r ia l Experim ent and the R e spo nse S u r fa c e M ethodology (RSM) m athem atical models a re p o s t u la t e d to p r e d ic t t h e e x t r u s io n p r e s s u r e in R a d i a l E x t r u s io n , T h e average p ressure o b t a i n e d from t h e t h e o r e t i c a l a n a ly se s a re compared w ith t h o s e p r e d ic t e d from t h e m athem atical models and a re found to b e in good a greem ent. T he dependence o f t h e a v era g e pressu re o f r a d i a l e x t r u s io n on th e f r i c t i o n a n d on th e process parameters v i z . b i l l e t d ia m e t e r , cup diam eter and cup t h ic k n e s s has b e e n obs e r v e d .
F i n i t e Elem ent Method is u s e d to stud y th e p ropagatio n o f t h e p l a s t i c r e g io n in t h e deform ing b i l l e t .
Attem pt has e l s o b e e n made to a n a ly s e th e C o n ic a l E x t r u s io n process u s in g upper-bound method. Some experim ents a r e conducted t o v e r i f y t h e t h e o r e t i c a l r e s u l t s due to th e u P P e r-bound a n a l y s i s .
