Mehrab Madhoushi; Hamid Hatefnia
Abstract
In this study, ground penetration radar (GPR) was used to assess the internal defects and decay of structural old timber in buildings and compare it with the sound wood. For this purpose, twelve samples of three wood species of beech, oak and yew with dimensions of 120 × 60 × 400 mm, and ...
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In this study, ground penetration radar (GPR) was used to assess the internal defects and decay of structural old timber in buildings and compare it with the sound wood. For this purpose, twelve samples of three wood species of beech, oak and yew with dimensions of 120 × 60 × 400 mm, and as flat sawn were selected. Two samples from beech species with severe decay and two samples from oak species with mild decay were selected from old buildings. Sound and completely dry samples of these species (two samples from each species) were also obtained from forest trees as an indicator. Four yew samples without decay were selected only from the old buildings. Holes with a diameter of 2 and 8 mm were drilled in decayed and also two yew samples. The samples were scanned perpendicular to the fibers direction using a HF antenna of 2.3 GHz. The condition of data collection and processing were the same for all samples. After the initial data collection, in order to increase the resolution and better interpretation of the image, different filtration process was applied using image processing software Reflexw. The results showed that the relative dielectric coefficient was higher in decayed wood, and due to the difference in reflection coefficient between sound and decayed wood, they can be distinguished from each other. It was also possible to detect holes of 8 mm in oak and yew species.
Mehrab Madhoushi; Baratali Keshtegar
Abstract
In this study, the effect of epoxy resin modified by carbon nanofibers (CNFs) was investigated at three levels of zero, 0.4 and 1.5% on the strength properties of common corner joints in the furniture industry. Carbon nanofibers were dispersed in the adhesive polymer matrix by ultrasonic device and test ...
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In this study, the effect of epoxy resin modified by carbon nanofibers (CNFs) was investigated at three levels of zero, 0.4 and 1.5% on the strength properties of common corner joints in the furniture industry. Carbon nanofibers were dispersed in the adhesive polymer matrix by ultrasonic device and test specimens of joints were prepared using cut MDF pieces with desired dimensions and wooden dowel with diameters of 8 and 10 mm and penetration depth in two levels (D2 and D3) and using reinforced epoxy by CNFs. A total of 12 treatments with three replications were evaluated separately for each of the compressive and tensile tests and the flexural moment capacity of the joints specimens was evaluated at a speed of 3 mm/min. The results showed that by increasing the percentage of CNFs, diameter and penetration depth of dowel wood in the compression test, the flexural moment capacity 1.2,, 1.2 and 1.2 times, and in the tensile test 1.3, 1.1 and 1.2 times, respectively, increased compared to the control samples. In general, according to the research variables, it can be said that carbon nanofiber was able to improve the strength properties of epoxy resin and thus the joints. The level of 0.4% CNFS, diameter 10 mm and penetration depth of D2 dowel wood had the best effect on the strength of joints in two types of loading
Management and Economics wood
Mehrab Madhoushi; Vajihe Mojerian Galogahi; Mohammadreza Masteri Farahani
Abstract
Radiography is a method of non-destructive for evaluating the quality of wood construction machinery in order to detect the defects due to natural degradation. The objective of this study was to investigate the assessment of Poplar (Populus deltoides) and beech (Fagus orientalis) wood defects arising ...
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Radiography is a method of non-destructive for evaluating the quality of wood construction machinery in order to detect the defects due to natural degradation. The objective of this study was to investigate the assessment of Poplar (Populus deltoides) and beech (Fagus orientalis) wood defects arising from the decaying by using x-ray non-destructive method. In this study, for each of species, uncolored (no coating) and colored samples by acid catalyzed lacquers and nitrocellulose lacquers were used. Decay resistance test based on modified ASTM D1413 standard was performed. The decay process was done in the periods of 1, 2 and 3 months with use of Coriolus versicolor fungus at laboratory condition. After each of these periods, for the decay of the samples, x-ray imaging by using an imaging at the lateral, tangential and radial direction was done. Results of weight loss confirmed the presence of decay in the radiographic images. The results showed that after 1, 2 and 3 months of exposure to fungus, fungal degradation leads to weight loss in the painted and unpainted samples. So that, the weight loss caused by decay in beech was less than poplar samples. As well, the weight loss of unpainted was less than painted samples, which was also statistically significant. The x-ray results of unpainted and painted samples at the cross, tangential and radial directions indicate that decay has a more impact on beech in comparison to poplar wood structure. The study as well showed that the protective layer has partly a barrier for decay destruction in these samples.
Mehrabi Madhoshi; Maliheh Alizadeh
Abstract
In order to establish a kiln drying schedule for Iranian Beech (Fagus orientalis) lumbers of 5.5 cm thickness, commercially cut from Shast Kola region , 5 km distance from Gorgan. They were then dried under the program based on diffusion theory (from Malmquist's relations) were adopted to dry the lumbers ...
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In order to establish a kiln drying schedule for Iranian Beech (Fagus orientalis) lumbers of 5.5 cm thickness, commercially cut from Shast Kola region , 5 km distance from Gorgan. They were then dried under the program based on diffusion theory (from Malmquist's relations) were adopted to dry the lumbers to the final moisture content of 12±2 %. This program for three separate kiln charges and initial moisture content 66.6, 58 and 45 percent was developed. Initial drying bulb temperature (first step) 46 °C and wet-bulb temperature 45 °C was calculated and in three schedules were same. The severity of surface, end checks and warp (bowing, crooking, twisting) in the lumbers were measured before and after the drying process and quality control methods were used to analyze the wood defects. Results indicated that drying of beech lumber using this new schedule was satisfactory. Also intensity changes of defect in all three repeats were about acceptable quality and quantity. Superior characteristics of this program was no surface checks in samples because the moisture content was reduced slowly.
Composite wood products
Amineh Behzadi Shahrebabak; Mehrab Madhoushi; Mohammad reza MastriFarahani
Abstract
In this study, the effect of nanoclay and coupling agent on decay resistance and physical properties (including water absorption and thickness swelling) of nanoclay- Polyethylene- MDF sanding- powder composite were investigated. For this aim, MDF sanding dust and polyethylene were used as lignocellulose ...
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In this study, the effect of nanoclay and coupling agent on decay resistance and physical properties (including water absorption and thickness swelling) of nanoclay- Polyethylene- MDF sanding- powder composite were investigated. For this aim, MDF sanding dust and polyethylene were used as lignocellulose and thermoplastic material respectively. Also, Maleic anhydride grafted polyethylene (MAPE) was used in different weight percentages; 3% and 6% as a compatibilizer and nanoclay .Cloisite®15A was used in different weight percentages 2%, 4% and 6%.At first, raw materials were producted to fabricate granules by using twin-screw extruder. Then 36 panels (12 treatments by 3 repetitions) were made by hot pressing with 1 g/cm3 nominal density at dimensions by 30 cm × 28 cm × 1 cm. Then, water absorption and thickness swelling and decay resistant (loss weight) were investigated. Specimens were exposed to Trametes versicolor for 3 months, according to ASTM-D1413 standard. The results shown, water absorption and thickness swelling reduce with increasing MAPE significantly. While, at the time when nanoclay was added 2% (phr), water absorption and thickness swelling reduced significantly and then increased. Also, decay resistance was improved with increasing coupling agent and nanoclay.
Mohammad Aghakhani; Abolgasem khazaeyan; Mehrab Madhoshi
Abstract
The aim of this study was to investigate the factors affecting surface quality of paulowniawood during milling by advanced computer numerical control (CNC) machine. For this aimwood logs were provided and were converted to proper sizes (2.5 x 10 x 15 cm) and then airdried. The Variable of this study ...
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The aim of this study was to investigate the factors affecting surface quality of paulowniawood during milling by advanced computer numerical control (CNC) machine. For this aimwood logs were provided and were converted to proper sizes (2.5 x 10 x 15 cm) and then airdried. The Variable of this study were spindle speed of machine (10000 and 18000 rpm),feeding rate (6 and 12 m/min), cutting depth (1and 5 mm), cutting method (down and upmilling)and cutting pattern (tangential and radial). Roughness of cut specimens edge wereevaluated by profilometer method according to ISO 13565 standard. For evaluation of surfacequality Abbott group parameters (Rpk, Rk, Rvk) were used. Degree of effective of theparameters was evaluated by fractional factorial design as completely random design atconfidence level of 95%. The result showed that spindle speed, cutting method and feed rate areinfluencing factors on surface quality of milled specimens and their effect was significant. Withincreasing spindle speed and decreasing feeding rate the roughness decreased and surfacequality improved. In up-milling cutting method, degree of roughness was higher andconsequently surface quality was inferior. It is to be noted that cutting method in comparison toother factors had the high influence on surface quality. The rest variable did now haveindependent influence on surface quality at 95% Confidence level.
