Mechanical conversion of wood and wooden fittings
Mosayeb Dalvand; Ghanbar Ebrahimi; Kambiz Pourtahmasi
Abstract
In this study effect of staple length (penetration length) and its number in connection, on withdrawal capacity in face and edge of laminated veneer lumber (LVL) out of poplar was investigated. In this investigation, the staple with 3 and 4 cm penetration length and staple with 3, 4 and 5 cm penetration ...
Read More
In this study effect of staple length (penetration length) and its number in connection, on withdrawal capacity in face and edge of laminated veneer lumber (LVL) out of poplar was investigated. In this investigation, the staple with 3 and 4 cm penetration length and staple with 3, 4 and 5 cm penetration length for withdrawal capacity in face and edge were used respectively. Number of staples at 4 levels (2, 3, 4 and 5) were chosen as a variable. Results have shown that withdrawal capacity in face significantly increases with increase of penetration length. Withdrawal capacity in edge increases drastically with increase of penetration length from 3 to 4 cm, but increase in penetration length from 4 to 5 cm had no significant effect. Withdrawal strength capacity in face has increased with increase of staples number. But, increase of staple number had no significant effect on withdrawal strength capacity in edge. Maximum withdrawal capacity was observed in joints fabricated with penetration length of staple 4 cm and number of 5 staples in face and minimum those were observed with penetration length 3 cm and number of 2 staples in edge.
Physics and Mechanical Wood
foroogh dastoorian; Mohammad Layeghi; Ghanbar Ebrahimi; Mehdi Tajvidi; Seid Majid Zabihzadeh
Abstract
In the present study, creep rupture behavior of a bagasse fiber- polypropylene composite was investigated. Two accumulated damage model (EDRM and Wood) and an energy based failure model (R-W) were adopted to describe the load duration influence on the studied composite. Results have shown that at very ...
Read More
In the present study, creep rupture behavior of a bagasse fiber- polypropylene composite was investigated. Two accumulated damage model (EDRM and Wood) and an energy based failure model (R-W) were adopted to describe the load duration influence on the studied composite. Results have shown that at very high stress levels, the EDRM and Wood models underestimated and overestimated the time to failure than static value respectively. This was attributed to the difference between application of static loading and creep loading. Findings indicated that the all three models were able to describe the creep rupture behavior of the studied composite and among this; the Wood model has shown a better fitting with experimental data, statistically. Based on findings in the present research, it can be concluded that the R-W model was more conservative in predicting time to failure in comparison with the two other models, and the reason can be attributed to the difference between failure criteria in energy based models and accumulated damage models. Results also showed that with increasing stress levels, the secondary stage of creep will shorten and at high stress level, the tertiary stage of creep will be more dominant
Physics and Mechanical Wood
Hamideh Abdolzadeh; Ghanbar Ebrahimi; Mohammad Layeghi; Mehdi Ghasemieh; Seiad Ahmad Mirshokraei
Abstract
In this study, characteristics of wood-polymer fracture under mode I were investigated by double cantilever beam. In this regard, the properties of furfurylated specimens with three different levels of furfurylation (20%, 30% and 65%) were evaluated in both RL and TL systems. Results indicated that load-displacement ...
Read More
In this study, characteristics of wood-polymer fracture under mode I were investigated by double cantilever beam. In this regard, the properties of furfurylated specimens with three different levels of furfurylation (20%, 30% and 65%) were evaluated in both RL and TL systems. Results indicated that load-displacement curves from mode I fracture specimens were changed by furfurylation so that it was much clear on curves of TL system. These changes not only included curve slope in elastic and proportional limit zones, but also fracture zone and initiation of crack growth were included . Furthermore furfurylation and raising its content on both systems and especially on TL one, caused to change in stress intensity factor, KIC , and critical energy release rate , GIC. In both systems GIC were highly increased by increasing of furfurylation contents. This criterion demonstrated that the wood- polymer showed much toughness under mode I fracture. Moreover, variation of KIC values due to furfurylation at both systems was different with that of GIC. At the RL system, ascending trend was observed at KIC and GIC values by increasing furfurylation levels. But at TL system, KIC was decreased by furfurylation and this criterion enhanced by increasing of furan polymer in the cell wall. Generally, results of this research show that fracture toughness of wood is highly affected by furfurylation process
