Dealing with corners and changing geometry - The Boundary Element Method with Programming - page 338

see that the value, that should be constant, fluctuates widely if continuous elements are
used.

10 KN/m 2

Region 2

D

Region 3 Region 4

A C

B

Region 1

1,0 m 1,0 m 1,0 m

Figure 12.6

Vertical Displacements

0.25

t x continuous
t x discontinuous

0.2

0.15

0.1

0.05

A B C

0

-0.05

-0.1

-0.15

-0.2

0 1 2 3

distance x [m]

Figure 12.7 Tractions t at the boundary of regions 3 and 4 along the line ABC
If discontinuous elements are used the tractions, which are now evaluated at points
slightly inside, show no fluctuation and only a small jump which is due to coarseness of
the mesh. Indeed the diagram in Figure 12.7 indicates a gross violation of equilibrium