Utjecaj toplinske obrade drva divlje trešnje na otpornost na habanje i čvrstoću držanja vijaka

In its wise use, many properties of wood are important. Among these properties, wood abrasion resistance (AR) and withdrawal capacity of screws (WCS) are deemed to be relatively signifi cant. It is well know that heat treatment changes the resistance features of wooden materials by changing the structural characteristics of wood. Within the scope of this study, the effects were investigated of the temperature and duration of heat treatment of Wild Cherry (Cerasus avium (L.) Monench) on its AR and its WCS in the radial direction and tangential direction. The test results indicated that weight loss (WL) and thickness reduction (TR) remained almost the same in the radial direction specimen, but there was significant TR in the tangential direction specimen. As a result of these changes, the abrasion effect of the S-42 abrader diminished based on the increase in the number of cycles. However, in both the radial and tangential direction, the WCS decreased to a significantly greater extent in the heat-treated specimens than in the control specimens.Za brojne uporabe drva bitna su mnoga njegova svojstva, a među važnijima su otpornost na habanje (AR) i čvrstoća držanja vijaka (WCS). Dobro je poznato da toplinska obrada drva zbog promjene obilježja građe drva mijenja njegova svojstva otpornosti. U sklopu ovog rada istraživani su učinci temperature i trajanja toplinske obrade drva divlje trešnje (Cerasus avium (L.) Monench) na njegovu otpornost na habanje i čvrstoću držanja vijaka u radijalnome i tangencijalnom smjeru. Rezultati istraživanja pokazali su da se gubitak mase (WL) i smanjenje debljine (TR) uzoraka ne pojavljuju u radijalnom smjeru, ali je značajno smanjenje debljine zabilježeno u tangencijalnim uzorcima. Kao rezultat tih promjena, učinak abrazije primjenom S-42 abraziva smanjuje se s povećanjem broja ciklusa. Međutim, i u radijalnome i u tangencijalnom smjeru znatno se smanjuje čvrstoća držanja vijaka toplinski obrađenih uzoraka u usporedbi s kontrolnim uzorcima

Effect of some factors on solid wood parquet’s geometrical stability

Bu çalışmada; masif ahşap parkelerin geometrik kararlılığı araştırılmıştır. Ahşap parkelerin bünyesindeki geometrik değişimlerin incelenmesi amacıyla iki ağaç türünden iki farklı genişlikte elde edilen numunelere ön deney ve deneyler uygulanmıştır. Ön deneylerde numunelerin yoğunluk, radyal ve teğet doğrultuda genişleme ve daralma değerleri belirlenmiştir. Deneylerde numuneler farklı bağıl nem değerlerinde şartlandırılıp geometrik kararlılıkları belirlenmiştir. Bu aşamada numunelerin bir kısmına oluk açılmış, bir kısmı sistire edilip her işlemin ardından tekrar şartlandırılmıştır. Oluk açılmayıp sistire edilmeyen bir numune grubu da ardışık olarak şartlandırılmıştır. Deneylerin ardından numunelerin geometrik değişimleri elde edilen literatür bilgileri ve yapılan istatistiki test bulgularıyla birlikte değerlendirilmiştir. Sonuçta; parkelere oluk açılmasının geometrik kararlılığın iyileştirilmesinde fayda sağlamadığı; fakat sistire edilip ardışık döngülere tabi tutulmasının geometrik kararlılığın artmasına etki ettiği ortaya konmuştur. Ardışık olarak farklı iklim koşullarında kalan malzemenin geometrik kararlılığında genel olarak artış olduğu da bir diğer sonuçtur.In this study; the geometrical stability of solid wood parquet was searched. For determining the geometrical stabilization of specimens pre-tests and tests were carried on. Determination of density, radial and tangential shrinkage and swelling tests were carried on as pre-tests. In the laboratory tests; the specimens were conditioned at different relative humidity values, then the geometrical stability changes were measured. In this stage; different physical properties were created on some groups of specimens. Here the aim was searching the effect of different physical properties on geometrical stability. After the experiments; the results were evaluated with the literature and statistical test diagnosis. As a result; it is determined that grooving channels to solid wood parquets is not advantageous in improving the geometrical stability but the geometrical stability of the specimens which were scraped successively improved. Also; the geometrical stability of the specimens which are exposed to different climate conditions successively improved.Publisher's Versio

Micro-mechanical properties of oak wood and comparison with standard-sized samples

The aim of this study was to investigate micro-mechanical properties of Oak (Quercus petraea) wood and to compare with standard-size test specimens values. Bending strength, modulus of elasticity in bending, compression strength and tensile strength were determined using micro- and standard-size mechanical test samples. In the micro- and standard size samples, bending strengths were evaluated as 71,2 MPa and 99,4 MPa, modulus of elasticity in bending as 2741,3 MPa and 11394,1 MPa tensile strengths as 98,7 MPa and 93,8 MPa and compression strengths as 45,4 MPa and 46,6 MPa respectively.The results showed that the bending strength, modulus of elasticity and compression strength of the micro-size samples were lower compared to the standard-size samples, while the tensile strength was higher in the micro-size samples. The compression strength values of micro- and standard-size samples were not significantly different. The regression analyses indicated a positive linear regression between the mechanical properties of micro- and standard-size samples. Micro-size specimens can be used to estimate the mechanical properties of Oak wood when obtaining standard-size specimens is not possible.   PDF XM