Moisture-dependent dynamic elasticity of wood: A non-destructive evaluation under varying relative humidity conditions

Öz

This study investigates the influence of moisture content (MC), controlled via oven-drying and relative humidity (RH) at 45%, 65%, and 85%, on the dynamic elastic properties of poplar, fir, spruce, and pine wood. Ultrasonic non-destructive testing (NDT) was used to measure the sound velocity and calculate the dynamic modulus of elasticity (MOE) in the longitudinal (L), radial (R), and tangential (T) directions of the samples. The findings revealed that the highest sound velocity in the L direction was observed in fir (5018 m/s under dry conditions), followed by poplar (4935 m/s), spruce (4912 m/s), and pine (4637 m/s). Correspondingly, the dynamic MOE in the L direction reached up to 12412 MPa for spruce and 10751 MPa for pine. As RH increased, all species showed declines in sound velocity and elasticity, with the radial and tangential directions being more sensitive to moisture variation. Spruce demonstrated the highest reduction rate in elasticity with increasing RH, particularly in the radial and tangential directions, while fir showed relatively stable mechanical behavior. These results underscore the species-specific and anisotropic response of wood to moisture and confirm the effectiveness of ultrasonic NDT for characterizing hygro-mechanical performance. The outcomes contribute to enhanced material selection and their long-term durability assessments for wood applications exposed to variable environmental conditions.

Anahtar Kelimeler

• Dynamic modulus of elasticity
• Relative humidity
• Ultrasonic non-destructive testing
• Wood

Ahşabın neme bağlı dinamik elastikliği: Değişen bağıl nem koşullarında tahribatsız bir değerlendirme

Öz

Bu çalışma, fırın kurusu ve %45, %65 ve %85 bağıl nem koşullarında denetlenen rutubet içeriğinin; kavak, göknar, ladin ve çam odunlarının dinamik elastikiyet özellikleri üzerindeki etkisini incelemektedir. Boyuna, radyal ve teğet yönlerdeki ses iletim hızları, ultrasonik tahribatsız muayene (NDT) yöntemiyle ölçülmüş ve bu verilere dayanarak dinamik elastikiyet modülleri hesaplanmıştır. Bulgular, en yüksek boyuna ses iletim hızının fırın kurusu koşulda göknar türünde 5018 m/s olarak gerçekleştiğini, bunu sırasıyla kavak (4935 m/s), ladin (4912 m/s) ve çam (4637 m/s) odun türlerinin izlediğini göstermektedir. Buna karşılık, en yüksek boyuna yöndeki dinamik elastikiyet modülü ladin için 12412 MPa, çam için ise 10751 MPa olarak belirlenmiştir. Yükselen bağıl nem düzeyiyle birlikte tüm türlerde ses hızı ve elastikiyet modülünde düşüş gözlemlenmiş; özellikle radyal ve teğet yönlerde bu düşüş daha belirgin olmuştur. Ladin odunu, nem artışına bağlı olarak elastikiyette en yüksek azalmayı gösterirken, göknar odunu daha kararlı bir mekanik davranış sergilemiştir. Bu sonuçlar, odun türlerinin rutubet karşısındaki anizotropik ve türlere özgü tepkisini ortaya koymakta ve ultrasonik NDT yönteminin higro-mekanik performansın belirlenmesinde etkinliğini kanıtlamaktadır. Çalışma bulguları, değişken çevresel koşullarda kullanılacak odun malzemelerinin seçiminde ve uzun vadeli dayanıklılık değerlendirmelerinde önemli katkılar sunmaktadır.

Anahtar Kelimeler

• Dinamik elastikiyet modülü
• Bağıl nem
• Ultrasonik tahribatsız muayene
• Odun

Kaynakça

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