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“MAINTENENCE OF THE CULTURAL HERITAGE CONSTRUCTIONS FROM THEIR COMPREHENSION AS A WHOLE” - MACH Second preparatory meeting of consortium partners OPD Lab Restauro 28 February 2007. AC oustic E nergy A bsorption D iagnostic D evice – ACEADD.

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slide1

“MAINTENENCE OF THE CULTURAL HERITAGE CONSTRUCTIONS FROM THEIR COMPREHENSION AS A WHOLE” - MACH

Second preparatory meeting of consortium partners OPD Lab Restauro

28 February 2007

ACoustic Energy Absorption Diagnostic Device – ACEADD

  • Among innovative portable technologies for NDT analysis and the diagnosis of degradation phenomena, the employment of a diagnostic device for the evaluation of the degree of deterioration of frescos is proposed. The proposed tool is an acoustic device based on the acoustic energy absorption phenomena evaluation in heterogeneous structures, such as antique frescos and mural paintings in general. It provides 2D and 3D acoustic maps for the localization and characterization of detachments, fractures and delaminations. This tool provides to restaurateur artists objective data in the following fields:
  • Diagnosis of the degree of deterioration of mural paintings;
  • Evaluation of consolidation treatments based on purposely defined criteria;
  • Time evolution monitoring of detachments by means of periodic exams, integrated by correlation to environmental data.
  • (G. B. Cannelli, P. Calicchia, Italian Patent N. RM 99 A000410; USA Patent US 6728661 27, European Patent EP 1190243B1")

CNR – Institute of Acoustics “O. M. CORBINO”

Paola Calicchia: paola.calicchia@idac.rm.cnr.it

slide2

(4) ACQUISIZIONE E SIGNAL PROCESSING:

  • MEASUREMENT OF ACOUSTIC PRESSURE P(t) AT RECEIVER

(standard distance from the surface 30cm)

  • P(t) PROCESSED BY MEANS OF CEPSTRUM ALGORITHMC(t)
  • FROM C(t) h(t-t) IS OBTAINED

CEPSTRUM

p(t)

FFT P(w)

Ln|P(w)|2

IFFT

C(t) = Ci(t)+(L1/L2) h(t-t)

(2)

(1)

Roughness map

Absorption map

2 matrices

(n x m)

(3)

(4)

L=c t / 2

h(t-t)

ACoustic Energy Absorption Diagnostic Device – ACEADD

DEVICE UNITS:

(1) TRANSMITTING -RECEIVING UNIT

(2) TRANSDUCERS CIRCUITRY

(3) AUTOMATIC X-Y SCAN UNIT

(4) REMOTE UNIT FOR DATA ACQUISITION,

SIGNAL PROCESSING AND MOTION CONTROL

  • (1) TRANSMITTING -RECEIVING UNIT :
  • SOURCE S (O.515) kHz
  • MINIATURE WIDE BAND OMNI-DIRECTIONAL RECEIVER M (O.0515) kHz
  • IN CO-AXIAL CONFIGURATION AND NORMAL INCIDENCE GEOMETRY
slide3

2-D

overlaying the fresco image

2-D

180

180

3-D

160

160

140

140

120

120

ABSORPTION MAP

max abs. 52%

OTHER ANALYSIS:

100

100

Vert. Axis (cm)

Vert. Axis (cm)

MODAL ANALYSIS ALONG SPECIFIC LINES

80

80

ROUGHNESS MAP

max height 14 mm

(%)

(mm)

EVALUATION OF THE THEORETICAL MODEL FOR DETACHMENTS ACOUSTICAL BEHAVIOUR

60

60

100,0

35,00

90,00

31,50

80,00

28,00

40

40

70,00

24,50

60,00

21,00

50,00

17,50

20

20

40,00

14,00

ANALYSIS OF CONSOLIDATION TREATMENTS

30,00

10,50

2-D ABSORPTION MAP

threshold set at 30%

20,00

7,000

0

0

0

8

16

24

32

40

48

56

64

72

80

88

0

8

16

24

32

40

48

56

64

72

80

88

10,00

3,500

0

0

Hor. Axis (cm)

Hor. Axis (cm)

ACEADD – Acoustic Images

The device was tested on laboratory model realized by OPD and on real frescos

slide4

ACEADD – Available Scan units for in-situ measurements

At present

a linear scan unit

and

an X-Y scan unit

are available