On the Foundation of Circular-Saw Stability Theory

The buckling and critical speed saw stability theories for predicting the flatness of a circular saw are discussed. Laboratory experiments were performed for evaluation of the stability concepts. The experiments include accurate measurement of the saw-disc natural frequencies or frequency spectrum and the measurement and inclusion of thermal effects in saw-disc stability analysis

Analysis of Optimal Roll Tensioning for Circular Saw Stability

When a circular saw is used to cut wood, a substantial and increasingly important fraction of the raw material is wasted because of the excessive width of the sawcut. The process of "roll tensioning" is studied here, whereby sawblade thickness, and hence material loss, can be significantly reduced while still maintaining sawblade stability. A theoretical model is developed that accurately describes the localized plastic deformation that takes place during roll tensioning, the associated residual stresses, and the resulting changes in sawblade natural frequencies. Experimental measurements of the residual stresses and natural frequencies confirm the theoretical predictions. The mathematical model allows reliable prediction of optimal tensioning conditions for any given saw operating state and development of automated control of the tensioning process. An example is presented in which the thickness of an optimally tensioned circular sawblade is 33% smaller than the thickness of an untensioned sawblade of equivalent transverse stability

Biology of the Klamath midge, Chironomus utahensis

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Parametric Excitation Of An Axially Moving Band By Periodic Edge Loading

Simple torsion parametric resonance and combination torsion-bending parametric resonance can be excited in an axially moving band by an in-plane periodic edge loading that is normal to the longitudinal axis of the band. The model simulates band saws, belts, magnetic tapes and like systems under edge forces. Sum combination instabilities, in particular, permit the excitation of low frequency resonances by higher frequency edge forces. Simple bending, combination torsion-torsion, combination bending-bending and difference type parametric instabilities are not excited by periodic normal edge forces. The space of band parameters leading to parametric instability shrinks with increasing axial tension and with increasing band velocity. © 1986 Academic Press Inc. (London) Limited

Vibration Coupling In Continuous Belt And Band Systems

Small transverse oscillation of an endless band supported by wheels couples the response of the free spans of the band to oscillation of the wheels. The coupling arises from the finite curvature of the free spans of the band when its bending stiffness is finite. Significant modeling error can occur if a single span of the band is modeled as a simply supported, axially moving beam. The coupling provides an opportunity to dissipate vibration energy. Experiments and finite element analyses support the coupling discussion presented. © 1985 Academic Press Inc

Disposal of Household Wastewater in Soils of High Stone Content (1981-1983)

Four experimental filter fields were constructed with built-in monitoring equipment in Nixa soils. These soils contain many chert fragments and a fragipan about 60 cm below the soil surface. The fragipan restricts downward movement of water and is the designlimitingfeature. The four filter fields were: 1. A standard filter field, 76 cm deep. The bottom of the trench was in the fragipan. 2. A modified standard filter field, 30 cm deep. The bottom of the trench was above the fragipan. 3. A modified pressure filter field, 40 cm deep. The bottom of the trench was above the fragipan. In addition, a pressure-distribution system was used to insure uniform distribution of effluent in the trench. Inadvertently, this field was installed in a different soil, and the results cannot be compared directly with the other three. 4. Another modified pressure filter field with the bottom of the trench only 6 cm below the soil surface. Observation of these systems confirms that placing filter fields higher in the soil above the hydraulically limiting horizon results in improved hydraulic performance. The presence of the fragipan amplified the adverse effects attributable to climatic stress. The seepage beds which are higher in the soil profile are able to handle the effluent load and climate load with less danger of surfacing

Theoretical and experimental stability of two translating cable equilibria

Previous theoretical investigations of translating cables have been focused on the sagged cable equilibrium referred to here as the minimum catenary. The minimum catenary is stable for finite translation speeds [1, 2] and asymptotically approaches a buckling instability as the translation speed tends to infinity [2]. Experimental evidence presented in this paper validates this conclusion and the cable theory established in reference [2]. A second translating cable equilibrium is predicted in which the cable stands in the shape of an arch. This equilibrium, referred to as the maximum catenary, collapses for low translation speeds but becomes stable for sufficiently high translation speeds. The stability of the high speed maximum catenary is confirmed by experiment.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/28058/1/0000497.pd

Disposal of Household Wastewater in Soils of High Stone Content (1977-1980)

Two experimental septic tank filter fields were constructed with built-in monitoring equipment in Nixa soils. These soils contain many chert fragments and a fragipan about 60 cm deep which restricts downward water movement and is the design-limiting feature. The standard filter field (76 cm deep) was built into the fragipan and the modified standard filter field (30 cm deep) was placed above it. During 30 months\u27 observation, the modified standard performed better than the standard filter field. Maximum rise of effluent in the standard and modified standard came within 11 and 19 cm of the soil surface, respectively. Performance of these systems indicates filter fields should be designed to function during climatic stresses, i.e. when the soil has a maximum hydraulic load and surfacing may occur. Filter fields should be designed to withstand a stress period of specified intensity. The filter fields in this study were observed under less than normal stress. Therefore, their long range performance is less clear. Our observations indicate that filter field performance is related more to rates of water movement than to stone content. Major influences on filter field performance are rates and directions of water movement, stress period intensity, designs, and construction techniques