1.Instrument supported tree evaluation in Hungary
Ferenc Divos
University of West Hungary
Jozsef Bodig wood NDT Laboratory
Beijing,
16th International Wood NDT Symposium
October 12-14, 2009

2. Content
Visual tree evaluation
Acoustic test, single path
Acoustic tomography
Acoustic root detection
Pulling test
Seedling test
Conclusions
3. Human caseTree case
1st step: visual investigation
2nd step can be:
- X-ray
- Ultrasonic
- CT, or MR
-
Arborist and patient
2nd step: NDT
- acoustic tomography
- pulling test
- root detection
- tree mechanics
4. 1.Visual tree evaluation
Goal: tree related risk reduction.
Requirement: well trained expert.
Expert focusing to...
5. ... holes
6. ... openings, truntcations
7. ... fungi fruits, wounds
8. ... crone structure, tree shape
9. ... soil conditions, environment
10. Failure type 1.
11. Failure type 2.
12. Accident in Budapest, 2008
13. 14. 2.Acoustic defect detection
Single path (2 sensors)
15. Principle of decay detection
Sound propagation in an intact and in a decayed tree.
16. Principle of decay detection
17. Principle of decay detection
18. FAKOPP Microsecond Timer
Measurement perpendicular to the grain
19. 20. Evaluation of measurement results
The relative velocity change (RVC) is a measure of the defect size. If RVC is lower than 90% of the velocity in an intact tree, the tree contains an internal defect.
21. Sound propagation
Oak disk, grid size is 2 by 2 cm, time resolution is 20 s.
22. The setup for wave mapping
23. 24. 25. 26. 27. 28. 29. 30. 3. Acoustictomography
by using more sensors
31. Intact poplar trunk
32. Decayed poplar trunk
33. FAKOPP 2D Acoustic Tomograph
34. 35. 36. 37. 38. 39. 40. 41. 42. 43. 44. 45. 46. 47. 48. FAKOPP 2D
Acoustic Tomograph
49. Linden and
Nut tree
50. 51. 52. 4.Acoustic Root Detection
53. Signal attenuation in soil is high, high sensitivity sensor is required
Amplitude (mV)
Distance (m)
54. P-vawe velocity in soil is 300 m/s
Distance (mm)
Propagation time (ms)
Velocity in root is 3000 m/s
55. Theoretical wavefront around a tree
56. Soil velocity depends on depth
57. Setup for acoustic root detection
58. 59. High sensitivity (10V/g)
soil sensors
60. 61. Velocity distribution around a tree
62. 63. 64. 65. 66. Root depth is measured by a steel bar.
67. 68. 69. 70. 71. Limitation of acoustic root detection
Large rocks, fence, concrete roads guidesthe sound propagation.
Technique is working well in parks and forest, but limited in urban area.
72. 5.Pulling test
73. Generalized
Inclination -
tipping load curve
From Koch, 1989
74. 75. Inclination sensor
76. Force sensor
77. Force display
78. Loading device
79. Pulling test in progress
80. Fitted curve and extrapolated maximum load
81. Evaluation
Generalizedinclination curve:
= 1/3 tan(p/73,85) +0,00005 p2- 0,0009 p
where::inclination in degree
p:force in % of maximum load.
82. 83. Inclination (degree)
Force (N)
84. Inclination (degree)
Force (N)
85. Results of pulling test
86. Limitations of pulling test
Uncertain factors:
wind speed,
drag factor,
curve extrapolation,..
Load is not static, but dynamic.
Trees are falling down not only in storms,
but sometimes in wind silent condition.
87. Paulownia tomentosa trees in the yard of city the hall Kecskemt, the city of Zoltan Kodly
88. Kecskemt, city hall
89. 90. 91. 92. 93. Mechanical model for tree stability evaluation
94. 95. Green wood material compression strength can be predicted by MOE.
A stress wave velocity in fiber direction, together with the nominal density of the tree, provides the dynamic MOE and compression strength.
96. Tree stiffness determination and strength prediction
MOE=V2
Higher velocity:
higher MOE
higher strength
longer fibers
low microfibril angle
97. 6.Ultrasonic seedling test
98. Shear type sensor
99. Sensor attached to seedling
100. Sensor attached to seedling
101. Testing oak seedling
102. 7.Conclusions

Visual Tree Evaluation is the most common tree evaluation technique.

103. Recently acoustic test becoming a standard tree evaluation technique in Hungary. 104. Acoustic technique is a reliable tool for tree trunk evaluation. 105. Acoustic root detection technique is approved in the practice. 106. Instrument supported tree evaluation increases tree safety, reduces tree related risk.