Plow Power Requirements for Forestry Site Preparation
Abstract In this field study, data were collected to determine power requirements required by a trailing site preparation plow and the magnitudes of dynamic forces experienced by a plow during normal operation and during impact with stumps or other obstructions. Drawbar pull data were collected from five different tillage treatments on a recently harvested loblolly pine (Pinus taeda) site in central Alabama. The five treatments were: 1) a coulter, ripping shank, and four bedding disks; 2) a coulter, ripping shank, and two bedding disks; 3) a coulter and ripping shank; 4) a coulter alone; and 5) a ripping shank alone. A 330 kN [75 000 lb] capacity tension load cell was used to measure the drawbar load, a GPS receiver recorded tractor speed, four direct current displacement transducers (DCDT’s) monitored the depth of the disks, and two optical tachometers measured the speed of the tractor’s front and rear drive shafts. Each treatment produced significantly different drawbar loads (to alpha levels less than 0.001). The resulting mean loads were 46.0 kN [10 300 lb], 33.5 kN [7530 lb], 31.5 kN [7080 lb], 15.8 kN [3560 lb], and 43.4 kN [9760 lb] for treatments one through five, respectively. Maximum recorded drawbar load during a collision with a stump was 338.9 kN [76 188 lb].
Subsoil compaction by vehicles with high axle load—extent, persistence and crop response
Abstract Extent and persistence of soil and crop responses to subsoil compaction caused by vehicles with high axle loads are reviewed and methods to protect the subsoil from permanent deterioration are discussed. Traffic by vehicles with high axle loads on soils with high moisture contents generally causes deep subsoil compaction. At an axle load of 10 Mg, compaction typically penetrates to a depth of 50 cm. With still higher loads, compaction to a depth of 1 m has been reported. Subsoil compaction is very persistent. At depths of more than 40 cm it is virtually permanent even in clay soils in regions with annual freezing. Deep subsoil compaction also causes persistent and possibly permanent reductions of crop yields. Complete amelioration by mechanical loosening is usually impossible and definitely expensive. From a soil productivity point of view, limits for mechanical stresses in the subsoil are needed. These may have the form of axle load limits for the vehicles or a combination of limits for the axle load and for some other important factors, such as the ground contact pressure of the running gear or the per cent water saturation of the soil at the time of trafficking. Guidelines for such limits should preferably be worked out in an international joint effort.
Flow and Compaction During the Vacuum Assisted Resin Transfer Molding Process
The flow of an epoxy resin and compaction behavior of carbon fiber preform during vacuum- assisted resin transfer molding (VARTM) infiltration was measured using an instrumented tool. Composite panels were fabricated by the VARTM process using SAERTEX(R)2 multi-axial non- crimp carbon fiber fabric and the A.T.A.R.D. SI-ZG-5A epoxy resin. Resin pressure and preform thickness variation was measured during infiltration. The effects of the resin on the compaction behavior of the preform were measured. The local preform compaction during the infiltration is a combination of wetting and spring-back deformations. Flow front position computed by the 3DINFIL model was compared with the experimental data.