This paper aims to introduce a finite element model to investigate the performance of bent leg (BL) plow and investigate the performance of new design as compared to a conventional one using finite element method approach (FEM).The difference between the modified and conventional BL plows is the direction of angle between the projection of cutting blade on horizontal plane normal to plow shank and the line perpendicular to the plow shank in the same plane. The effects of BL plow geometry on plow performance for both plows were studied and the results were verified experimentally. Conventional (B1), and modified (B2) designs of BL plow were modeled at three rake angles (R1= 7.5°, R2= 15° and R3= 22.5°), therefore a total six treatments were considered for both theoretical and experimental studies. A three dimensional non linear finite element model was developed using appropriate FEM software (ANSYS 8.1). The soil media was considered as elastic-perfectly plastic with Drucker-Prager material model. Soil meshing, contact elements and soil frictional properties were updated after each incremental time step. Variation of draft force as calculated by the FEM model indicates that the minimum and maximum draft forces correspond to B2R2 and B1R3 treatments respectively. The experimental results of draft force were in good agreement with predicted data.
Mechanical damage degrades fruit quality in the chain from production to the consumption. Damage is due to static, impact and vibration loads during processes such as harvesting, transportation, sorting and bulk storage. In the present study finite element (FE) models were used to simulate the process of static bruising for apple fruits by contact of the fruit with a hard surface. Three dimensional finite element models with three different layer material models were developed. The force relation between the cortex and elastic core was simulated using a gluing mechanism. An external point load simulating the wall pressure was applied on the fruit skin. The elastic, plastic and total strain energies in apple fruits were calculated to estimate mechanical bruising. In order to validate the simulated data, compression tests were carried out using a universal testing machine. Force- deformation graphs were plotted and the area of the region restricted by the curve and deformation axis between zero and 1.5, 3 and 4.5 mm deformations were obtained at five replications to assess the stored strain energy in the fruit. Results revealed that any increase in applied external displacement increased the bruised area. A high correlation (r=0.994) was observed between bruised area and amount of stored strain energy. Other results indicated that the bruised area highly depended on skin elasticity. Increasing in skin modulus of elasticity decreased the bruised surface.
Tissue engineering has emerged as an alternative to typical graft surgeries in recent decades. This study focuses on exploring the potential of BioMIL-4, a biological metal–organic framework (BioMOF), and its composite with chitosan and alginate as natural polymers for the fabrication of scaffolds in bone tissue engineering. BioMIL-4 consists of calcium ions as metal nodes and alendronate, a drug used to treat osteoporosis by blocking osteoclast activity, as an organic ligand. Both components contribute to enhancing the bone healing process during the degradation of BioMOF. In the first step, a specific synthesis procedure was employed to achieve biomimetic mineralization of BioMIL-4 on chitosan nanofibers with varying weight ratios. This resulted in an increased degradation rate of BioMIL-4 and an improved mechanical strength of the natural polymer. Characterization analysis tests confirmed the successful synthesis of rod- and ribbon-shaped BioMIL-4 in the presence of chitosan nanofibers. In the second step, solutions of alginate and chitosan particles were added to the BioMIL-4/chitosan nanofibers with different weight ratios, followed by cross-linking using a CaCl2 solution. The complete scaffold was characterized by various techniques such as SEM, XRD, and FT-IR. The water absorption capacity of scaffolds ranged from 6 to approximately 10 times their initial weight. The scaffolds exhibited considerable biocompatibility, with cell viability exceeding 80% (assessed by MTT assay) after 72 h and reaching close to 100% in the best-case scenario. The porosity of the scaffolds was evaluated using the liquid displacement method, with values ranging from 82 to 94% across the three main scaffolds. Additionally, the degradation rate and mechanical strength of scaffolds were assessed, and the synergistic effects of biomimetic mineralization of BioMIL-4 on chitosan nanofibers, along with its proper blending with chitosan particles and alginate solutions, resulted in improvements in both parameters.
ABSTRACT- Bruising degrades the quality of fresh apple fruits. Reducing bruise damage is of utmost importance in designing and developing processing equipments. The main objective of the present study was to introduce an analytical method to predict the allowable static load applicable to apple fruits. To predict the strain energy absorbed by the fruit, a point load was applied on the solid spherical object. The strain energy of the spherical element was extended to the whole body using a triple integral in the spherical domain. In order to verify the results, a series of compression tests were carried out using a universal testing machine on an apple kept at two different storage and initial fruit temperatures (zero and 25oC). The results showed a strong polynomial relation with a coefficient of determination of 0.990 between the value of the theoretical stored strain energy and the experimental one. Also, it was found that the size of the bruised area can be determined by its corresponding theoretical stored strain energy with an error less than 3.6 percent.
ABSTRACT-This paper aims to develop a new design of a bentleg (BL) plow and to determine its performance as compared to the conventional one using finite element approach. The difference between the modified and conventional BL plows is the direction of angle between the projection of cutting blade on horizontal plane normal to plow shank and the line perpendicular to the plow shank in the same plane. The conventional (B1), and modified (B2) designs of BL plow were modeled at three rake angles R1= 7.5°, R2= 15° and R3= 22.5°. A three dimensional nonlinear finite element model was applied using ANSYS 8.1, 2004. The variation of calculated draft force by model indicated that minimum and maximum draft forces were obtained for B2R2 and B1R3 treatments, respectively. The minimum vertical force was measured for B1R1 treatment. Calculated draft and vertical forces were in good agreement with measured ones. An increasing positive x-y shear stress zone in the modified BL plow causes the soil lifting increase as compared to the conventional one. Similarities of the Von Mises stress contours to stress characteristic curves emphasize the validity of the analysis. The small size of the plastic Von Mises strain contours (plastic bubble) in the modified plow emphasizes the fact that the force requirement of the modified BL plow is less than that of the conventional one. Similarity of the stress distribution contours in soil block and the stress characteristic curves show the validity of the modeling.
In the present study a finite element investigation of the soil tillage process is described using the elastic-plastic constitutive material model. For tillage systems, accurately predicting the forces acting on the blade is of prime importance in helping to enhance productivity. The soil properties, such as soil cohesion, internal friction and Poisson's ratio and the analysis conditions like mesh density in finite element analysis were investigated and its effect on reaction forces were calculated. A 3D finite element analysis of soil-blade interaction was carried out to investigate the behavior of the soil-blade interface and study the effect of soil properties on predicted forces. Results reveal the soil cohesion and soil internal friction has a significant effect on the cutting forces. The soil Poisson's ratio has no significant effect on the reaction forces. Increasing the mesh density cause an increase the accuracy of the analysis and increase the solution time. Results showed that the trend of variation of soil reaction forces with respect to tool displacement is the same at all level of the independent variables.
The present study was conducted to design and develop a new shape of bent leg plow (BL). The main difference between modified and conventional BL plows is the direction of angle between cutting blade and the line perpendicular to the plow shank. Soil-bin tests were conducted to study the performance of the modified plow as compared to the conventional one. The draft force requirement was measured in both designs at three rake angles (7.5, 15, and 22.5). Changes in draft force requirements and soil physical properties including plowed soil bulk density and cross-sectional area of soil disturbed were measured and compared for both designs. Soil disturbance efficiency was also calculated for all treatments. Draft force was significantly affected by blade type and rake angle and was minimum at rake angle of 7.5. Other results showed that the modified BL plow was the most energy efficient treatment when operating at a rake angle of 15. Minimum plowed soil bulk density (1.04 Mg m-3) was observed in the energy efficient treatment (modified BL at rake angle of 15). The lower draft requirement and considerable improvement in soil physical conditions suggested application of modified BL plow as a replacement for conventional model; it was especially true where the soil had excessive compaction.
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