Singularities and Constructive Methods for Their Treatment Proceedin

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IN E L L I P T I C

M. U.E.R.

PROBLEMS

DURAND

de M a t h ~ m a t i q u e s

Universit#

de P r o v e n c e

13331Marseille

Cedex 3

France

We a r e

concerned

space with The f i r s t into to

a crack. one,

obtain

tional

problem.

book,

the

the

are At

to

blems.

Uniform

an i n t e g r a l

are

ones.

able

In

to

framework

Thus

method,

the

of

solved Its

form

methods.

elasticity

is

as e x p l a i n e d

singularities

he o b t a i n s

order

to

all

problem

owing

solution

related

to

to

the

allows the

varia-

pseudo-differential

of

in

the

the

results

the

crack

defined

H s +i (F)

no

usual

the

G.I.

solution about

Eskin's along

the

. Here

the

regularity

= { u ~ Hs(F )

we d e f i n e

6

Hs ( F )

, the

for

a regular

s is

if norm

distribution

integral

curpro-

Then we

pseudo-diffe-

as t h e

some d e f i n i t i o n s

order

and we boundary

integer;

an i n t e r p o l a t e , if

equal

:

s ,

positive

equal is

Hs(r)

limit. of

equations,

by m e t h o d s

of

when

s > O. For e v e r y to to

s

H s (F)

is

posi-

and

boundary. u

in

s < O. IIull

the

a sequence

domain with

, ~ ~ Hs(Rn ) }

as t h e

= (H_s(F))'

we r e c a l l

Hs(F )

go t o

closed

approximated

and o t h e r s .

space of

as u s u a l l y F is

the

computations

clear,

Sobolev

in

of

by r e g u l a r

solve

us t o

limit

occur

Wendland

an i n t e g e r ,

allow

as t h e

numerical W.L.

of

equationsthat

estimates

be q u i t e

is but

integral

operator

of

Hs(F )

In

the

opinion,

infinite

method clear.

perform

methods

the

Hs(?)

our

These o p e r a t o r s

is

~s(F)

system

the

different

the

and S - w a v e s . bilinear

a-priori

Hs(Rn ) tive,

P-waves the

define

obtain

element

three

transforms

we use an a p p r o x i m a t i o n

order

rential

we s u g g e s t

in

wanted.

last, in

in

problem

expansionsof

computes

crack.

it,

The d i f f e r e n t i a l

Wiener-Hopf

C. G o u d j o

edge o f

ves,

In

elasticity

Bamberger,

waves

makes t h e

By u s i n g

that

of

explicit

operators

A.

one.

separation

linear

To s o l v e

due t o

a variational

usual

by t h e

II~lls.

F

u

in ~ i r ) ,

and z e r o

elsewhere.

105 Remark.- I f space

s > 0

is not equal to

k+1/2

Hs(C) i s t h e i r

S

space

Hoo(F).

( w i t h a weaker norm) the L i o n s ' s p a c e

has two s i d e s ,

and

I-

integer,

Hs(F ) i s the

HS(F) d e f i n e d by Lions and Magenes. When s = k=1/2,

integer,

F

, k

~-

on

positive

F , we p u t

For

H-I/2(F).

and n e g a t i v e , [~ =

k positive

s=-1/2, H I/2(F ) contains

if

@ has some t r a c e s

4 + - ~- = T r + ( ~ )

4รท

Tr-(~).

A.BAMBERGER'S METHOD.

To s i m p l i f y t h i s paper, we suppose t h a t the crack is a r e c t i l i n e a r curve ~ in the plane ~2 : F = { ( X l , X 2 ) ~ R2 ; 0 < x I < 1 , x 2 = 0 } We seek f o r the s o l u t i o n of the f o l l o w i n g problem :

nd

u i ~ H~ ( R 2 \ F ) ,

Ij~

(1)g

i=1,2,

such t h a t

~j a i j ( u ) + pw2ui = 0 , u