Testing the effect of transverse resonant vibrations on wood impregnation

Seeking to expand the range of operation and durability of wood articles, in many cases they must be impregnated with relevant materials. The process consumes a lot of time. Different technologies are applied for modification of depth and speed of impregnation. A method of vibrational wood impregnation is presented in this paper. It was determined that the transverse vibrations of scantlings in water are analogous to those in air, only the frequencies are different by 1.5 times. This study reveals that the amplitudes of vibrations in water and in air are close to each other, while the coefficient of damping in water is larger by 50 %. It is demonstrated that in many cases the scantlings undergoing resonant vibrations in the same time absorb up to 30 % more water than in the case of non-vibrant scantlings. The results of these investigations may be applied in wood impregnation industr

Study of resonance phenomena in acoustic wood boards

During development of various resonance systems - screens, acoustic boards, musical instruments parts, etc. it is important to obtain proper amplitude-frequency characteristic. In addition, in examination of wood and its articles it is necessary to evaluate the vibrations of viscous elastic timber structures. Resonance vibrations of different types of acoustic wood boards are investigated in the paper. Amplitude-frequency characteristic, fundamental modes of vibration and coefficient of damping in a wide frequency range are estimated. The relationships between perforation of acoustic boards and parameters of vibroacoustic processes are determine

Study of resonance phenomena in acoustic wood boards

During development of various resonance systems - screens, acoustic boards, musical instruments parts, etc. it is important to obtain proper amplitude-frequency characteristic. In addition, in examination of wood and its articles it is necessary to evaluate the vibrations of viscous elastic timber structures. Resonance vibrations of different types of acoustic wood boards are investigated in the paper. Amplitude-frequency characteristic, fundamental modes of vibration and coefficient of damping in a wide frequency range are estimated. The relationships between perforation of acoustic boards and parameters of vibroacoustic processes are determine

Estimating wood panels anisotropic properties by resonance vibrations method

In this paper the transverse resonance vibrations of glued-up panels and particle boards are under investigation. The viscous elastic properties of these articles are evaluated based on the theory of resonance vibrations. The calculating methods of mechanical systems and elastic bodies with infinity degree of freedom and finite elements and accesses to apply for wood articles are considered. It is shown that through their structure some modes of rectangular wood panels accords modes of elastic isotropic beam and their theoretical calculations of beam vibrations can be applicable. Anisotropic properties of wood panels are evaluated. It was estimated that the resonance frequency in plane of panel by 5 % and width of band of amplitude – frequency characteristic – by two times can vary. The results are obtained by estimating the modulus of elasticity and the damping coefficient of wood panel

Study of resonance phenomena in acoustic wood boards

During development of various resonance systems - screens, acoustic boards, musical instruments parts, etc. it is important to obtain proper amplitude-frequency characteristic. In addition, in examination of wood and its articles it is necessary to evaluate the vibrations of viscous elastic timber structures. Resonance vibrations of different types of acoustic wood boards are investigated in the paper. Amplitude-frequency characteristic, fundamental modes of vibration and coefficient of damping in a wide frequency range are estimated. The relationships between perforation of acoustic boards and parameters of vibroacoustic processes are determine

Badania nad sorpcją i właściwościami mechanicznymi naturalnego i modyfikowanego drewna brzozy

The research presented examined wood treatment at high temperatures. Wood specimens were tested at an original working station. In order to increase the durability, environmental resistance and size and shape stability of wood products, the wood underwent a modification process. One modification method includedhigh-temperature heating (140–230°C). Exposure to heat contributed to changes in the chemical composition and physical and mechanical properties of the wood.In addition, assortments of natural and modified birch wood were studied.The sorption properties of the wood were evaluated during the moistening and drying processes. The resonance vibration method was used to assess the modulus of elasticity and the coefficient of damping. The specimens were tested by subjecting them to 3-hour heating at temperatures of 120, 150, 180 and 210°C and soaking them in water afterwards. It was found that the modulus of elasticity of the heated wood increased by 12% and the coefficient of damping decreased by 40%. It was established that the amounts of water absorbed by the heated wood were 5 times smaller in comparison to the natural wood.Niniejsze badania dotyczyły obróbki drewna w wysokich temperaturach. Próbki drewna zostały przebadane z wykorzystaniem oryginalnego stanowiska badawczego. W celu podniesienia trwałości, odporności środowiskowej oraz stabilności rozmiarowej i stabilności kształtu produktów drzewnych, drewno poddawane jest procesowi modyfikacji. Jednaz metod modyfikacji obejmuje ogrzewanie w wysokiej temperaturze (140–230°C). Poddanie działaniu ciepła przyczynia się do zmian w składzie chemicznym oraz zmian właściwości fizycznych i mechanicznych drewna. Dodatkowo przebadano sortymenty naturalnego i modyfikowanego drewna brzozowego. Właściwości sorpcyjne drewna oceniono podczas procesów zwilżania i suszenia. Metodę wibracji rezonansowych wykorzystano do oceny modułu sprężystości oraz współczynnika tłumienia. Próbki przebadano, poddając je 3-godzinnemu ogrzewaniu w temperaturach 120, 150, 180 and 210°C i mocząc je potem w wodzie. Zaobserwowano, iż moduł sprężystości drewna poddanego obróbce termicznej wzrósł o 12%, a współczynnik tłumienia obniżył się o 40%. Ustalono, że ilości wody wchłonięte przez drewno poddane obróbce termicznej były pięciokrotnie mniejsze niż ilości wchłonięte przez drewno naturalne

Research on wood gluing factors by a resonant oscillations method

This paper presents the methodology and equipment that is applied for experimental investigation of glued wood articles and their components by means of resonant vibrations. It is demonstrated that beam and plate, which form wood assortments along and across grain, may be studied by using theoretical calculations based on deformed beam vibrations. In addition, research data of oak glued-up panels of varying width as well as adhesive and scantlings are included. It was determined that the increase of width of the panels (the number of scantlings) practically does not change the shape of their first vibration mode. However, the research revealed slight changes in the amplitude-frequency characteristic, i.e., the first natural frequency increased up to 5 %, and the bandwidth decreased by 30 %. Irrespective of additional factors, the modulus of elasticity of the glued-up panels was higher by 10 % in comparison to average modulus of elasticity of the used scantlings, whereas damping coefficient was lower by 40 %. Obtained results may be used to evaluate the behavior of glued-up panels in the zone of dynamical loads and to produce glued-up panels with proper parameter

Research on wood gluing factors by a resonant oscillations method

This paper presents the methodology and equipment that is applied for experimental investigation of glued wood articles and their components by means of resonant vibrations. It is demonstrated that beam and plate, which form wood assortments along and across grain, may be studied by using theoretical calculations based on deformed beam vibrations. In addition, research data of oak glued-up panels of varying width as well as adhesive and scantlings are included. It was determined that the increase of width of the panels (the number of scantlings) practically does not change the shape of their first vibration mode. However, the research revealed slight changes in the amplitude-frequency characteristic, i.e., the first natural frequency increased up to 5 %, and the bandwidth decreased by 30 %. Irrespective of additional factors, the modulus of elasticity of the glued-up panels was higher by 10 % in comparison to average modulus of elasticity of the used scantlings, whereas damping coefficient was lower by 40 %. Obtained results may be used to evaluate the behavior of glued-up panels in the zone of dynamical loads and to produce glued-up panels with proper parameter