The Structural Conservation of Panel Paintings

T C   T  P P 545

Ifthe same event occurred to an oak panel 1.25 cm thick (with the

other two dimensions the same), the bending stresses would be 9.8 Mpa.

Even though the 1.25 cm thick panel weighs half as much as the 2.54 cm

one, it incurs twice the stress. The measured breaking stress of white oak

at room temperature and 50% RH is approximately 8.9 Mpa. The thinner

panel will likelycrack in a 50-G topple accident. The 2.54 cm thick panel

would require a 100-G topple impact to crack it. If either panel were sup-

ported continuously around the edges, the risk of damage would decrease

by a factor offive.

0 20     40  60  80  100

Station (cm)

Sh

ea

rfo

rce

(N

)

2

1

0

21

22

23

24

3 1 Richard fig 19 eps

Figure 19
Shear in newtons (N) for a 2.54 cm wide strip
ofa 100 3 150 x 2.54 cm thick panel subjected
to a 50-G topple accident.

0 20     40  60  80  100

Station (cm)

Be

nd

ing

mo

me

nt

(c

m-

N)

80

70

60

50

40

30

20

10

0

31 Richard fig 20 eps

Figure 20
Bending-moment diagram for a 2.54 cm wide
strip ofa 100 3150 3 2.54 cm thick panel
subjected to a 50-G topple accident. The
bending moments of panels subjected to
topples can be quite high.