Applied Mechanics and Materials Vols. 799-800

Abstract: The development of bio-mimetic scaffold for tissue engineering proposed a novel method to tissue or bone repairing. The biological and physical properties of the scaffold have been recognizing such as biocompatibility, porosity, pore size, and biodegradability. In this work, Chitosan, Hydroxyapatite (HA), and Fibroin were used for bone's scaffold fabrication by freeze drying technique. Those materials are known as biodegradable materials that serve different properties in bone's scaffold. In common fabrication process, the fibroin treatment is requiring for increasing the stiffness of the fibers. Recently, the fibroin treatment is process before the scaffold fabrication. However, the treatment could process after the scaffold fabrication complete. Thus, we compared the biological and physical of the scaffolds between three conditions of fibroin treatment that consist of 1) Non-treatment (NON), 2) Pre-treatment (PRE), and 3) Post-treatment (POST). From the result, both of biological and physical properties, the PRE porous scaffold is the appropriated condition for this research. Finally, we are looking forward to compare the growth of osteoblast cells on the scaffold with different fibroin treatment and aim to implant those scaffolds for bone repairing in the very near future.

Abstract: Hydroxyapatite (HA) modified silica aerogel (SA) was synthesized based on 2 different techniques namely encapsulation and in-situ via aqueous colloidal sol-gel process. The structure of the synthesized HA modified SA have been studied using Fourier transform infrared (FTIR) spectroscopy. FTIR spectra of HA modified SA, derived from in-situ technique appear to be different from those of encapsulation technique and free HA, with the main difference lying in the phosphate bending absorbance. Results showed that the encapsulation technique preserved the native confirmation of HA in SA frameworks compared to in-situ technique. It confirms that the use of an aqueous sol-gel encapsulation route provides a promising approach for the stabilization of HA in SA networks.

Abstract: An aqueous tape casting process was employed to produce hydroxyapatite (HA) sheets. The effects of viscosity of slurry, blade height and speed on flexural strength and density of the sintered HA sheets were studied using central composite design (CCD). The flexural strength and the density were measured using a three-point bending test and Archimedes method, respectively. Results suggested that all parameters and the interaction between viscosity and speed had significant effects on both flexural strength and density. Under the conditions studied, the optimal conditions for the maximum flexural strength and density of the sintered HA sheet were obtained with the viscosity of 1532 mPa.s, the blade height of 3.34 mm and the speed of 6.27 mm/s.

Abstract: The need of the most precise manipulations in the orthopedic surgery concerns spine. The drilling takes place very often there. If spine cortices are broken by mistake then fatal problems appear as paralysis, block of breathing and death. Therefore in operation as pedicle drilling the far cortex perforation must be avoided. This paper shows that it can be done by bone drilling hand-hold robot ODRO. It is able to detect the bone far cortex and stops just before contact registration. Experimental results are presented. Also the results based on new algorithms and software are presented and discussed.

Abstract: Bone cutting is a well know procedure in orthopedics. Large cutting force causes overstressing of the bone which may result in trauma. Control penetration of the cutting tool into bone tissue is important to avoid unnecessary damage to the bone tissue. The purpose of this study was to measure and predict cutting force using experiments and Finite Element (FE) analysis when a plane cutter passes over the bone surface in the presence of irrigation. The effect of cutting speed, tool rake angle, depth of cut and width of the cutting face on the cutting force was found. The force was found to decrease with increase in rake angle and significantly rise with increase in depth of cut and width of cutting face. The cutting force was found unaffected by the range of cutting speed used in experiment as well as in simulations. The results obtained from this study strongly recommend the use of irrigation to minimize plane cutting force or force arising from similar cutting action for safe and efficient surgical incision in bone.

Abstract: The purpose of this paper is to realize some researches concerning the powder Co-Cr, the sintering compacts obtain after Direct Metal Laser Sintering manufacturing and the corrosion resistance in artificial saliva. The Co-Cr alloys are used frequently in dentistry to realize personalized dental crown, bridges, chapels, dental implants or microsurgery instruments. The Co-Cr powders are used in Direct Metal Laser Sintering technologies to obtain personalized dental crown with complex forms after a ”stl” file, realized after a tomography or oral scanning. Direct Metal Laser Sintering process is used to realize quickly a scale model of physical part or assembly using 3D computer aided design CAD data. This alloy must present good corrosion behavior and mechanical resistance to be used in medical domain.

Abstract: This work is devoted to modeling of nonlinear dynamics of the rotating drill-string taking into account initial curvature and finiteness of deformations. The drill-string is compressed by variable axial force. The case of flat bending of the drill-string with an initial curvature is studied, where drill-string considered as a one-dimensional rotating rod of a symmetric cross-section. A nonlinear model is developed on the basis of the variational principle Ostrogradsky-Hamilton and the theory of finite deformations. The numerical analysis of the model is carried out. The influence of bending forms and initial curvature of the drill-string on the amplitude of transverse vibrations is established.

Abstract: In the paper, a velocity and fluid flow status of the melting process in twin-screw extruder were analyzed. To explore the optimum producing parameters of expanding food, several models of the flow field and velocity of twin-screw extruder were created with fake plastic Newton fluid. Then the velocity distribution rules in the cavity space were simulated. With the valuable verification of experiments, the results showed that, the velocity distribution near the inner wall is uniform, and increases at the delivery of the extruder. The velocity rises in the teeth root than in the top of the screws. At the mesh field, the velocity was changed frequently. The experiment of popped extrusion verified the simulation conclusion.

Abstract: This paper describes the characteristics of the multi-DOF controllable mechanism type construction machinery, and has done the kinematic analysis on the work equipment of this new type loader. 3 dimensional model of the multi-DOF controllable mechanism type loader is established by Pro/E software, and describe the typical workflow of work equipment through step function. Through carried on the positive and inverse kinematics simulation used the dynamic simulation software of mechanical system ADAMS, we got the movement rules of the driving lever and the curve of the bucket dip angle. Finally, a small prototype model was built to test this new type loader.

Abstract: The ANSYS Workbench is used in this paper to analyse a kind of wind tunnel test model support platform with 5 degrees of freedom. The driving rod of the pitch motion is chosen as the main research project. By using static structural analysis, modal analysis and harmonic response analysis, a detailed analysis is made on the stress, deformation and frequency of the driving rod, and provides theoretical support for the future research on the stability of the institution.