Designing maxillofacial prosthesis for bone reconstruction: an overview

A cranio-maxillofacial region contains several bones and serves to protect and support the area, from the brain to the masticatory system. In this paper the clinical and research aspects of craniomaxillofacial biomaterials have been highlighted to serve as a guide into the wide world of their reconstructions. After a quick look into the anatomy, the review focuses on the causes of large bone defects in this region, and how they influence the designing process of the implant. Since it is a large area to unfold, only the maxillary, the mandible and the temporomandibular joints are highlighted. Understanding the biomechanics of mandible and temporomandibular joints is quite important, as it strongly influences the choice of the biomaterial. Thus, the latest techniques implemented to understand the biomechanics of the mandible are also highlighted. Via the finite element analysis, a simulation can help to identify the forces and the movements of the mandible and to predict the possible outcome of the implantation influencing the choice of the biomaterial.

Numerical Simulation of Reinforced Concrete beam Under Flexure Using Finite Element Method

Understanding the response of concrete structural components such as beams, columns, walls during loading is indispensable for the development of safeand efficient structures. The present report deals with the non-linear static analysis of a Reinforced Concrete (RC) beam, having dimensions 4000mmX400mmX 250mm, with 4 nos. of 16mm diameter bar as main reinforcements, 8mm diameter at 200mm c/c as shear reinforcement, with two faces of the beam as fixed modeled and analyzed when subjected to two point loads at one-third span from each fixed support using the Finite Element Analysis software Ansys. The behavior of the analyzed beam has been observed in terms of flexural behavior, load-deflection responses, and crack pattern for various loading conditions until failure load. Keywords: Finite element analysis, ANSYS, flexural behavior, Reinforced Concrete (RC) beams, material non- linearity, shear reinforcement.

Effect of Blade Thickness on Internal Flow and Performance of a Plastic Centrifugal Pump

Blade thickness is an essential parameter of the impeller, which has significant effects on the pump performance. The plastic pump generally adopts thick blade due to low strength of plastic. The effects of blade thickness on the internal flow and performance of a plastic centrifugal pump were discussed based on the numerical methods. Two kinds of blade profile, the constant thickness blade (CTB) and the variable thickness blade (VTB), were investigated. The results indicated that, for the CTB, when the blade thickness was less than 6 mm, the pump performance did not change significantly. When the blade thickness exceeded 6 mm, the pump head and efficiency decreased rapidly. The pump head and efficiency of CTB 10 decreased by 42.2% and 30% compared with CTB 4, respectively. For the VTB, with blade thickness in a certain range (6 mm–14 mm), the pump performance changed slightly with the increased of trailing edge thickness. The minimum blade thickness of the plastic centrifugal pump should be 4 mm based on the finite element analysis. A variable thickness blade (VTB 4-8-4) with the maximum thickness located at 60% chord length was proposed to improve the pump performance, and its efficiency was 1.67% higher than that of the CTB 4 impeller.

Investigation of ballistic performance on 3D compound structure fabric by finite element analysis

Ballistic performance and moldability are two important properties for 3D curved-surface ballistic applications. However, these two properties are contradictory to each other and impossible to improve at the same time, which is a technical issue that needs to be solved urgently in the research for ballistic materials for 3D curved-surface ballistic applications. In order to solve this issue, a new 3D compound structure fabric has been developed as part of our former research and has been shown to provide better ballistic performance with equivalent moldability compared to 3D angle-interlock fabric—a well-known 3D material for 3D curved-surface ballistic applications. Nevertheless, the ballistic performance of this new fabric itself is not clear, and further research is necessary. In this study, the ballistic performance of this new 3D compound structure fabric was investigated via the finite element analysis (FEA) model to examine energy absorption and penetration resistance. A ballistic test was also carried out to verify the results of the FEA model, and this demonstrated that the theoretical model was consistent with the experimental results.

Study of the Harmonic Analysis and Energy Transmission Mechanism of the Frequency Conversion Transformer

Since the transmission distance of submarine cable transmission is inversely proportional to the input frequency, to solve the problem of large losses in the transmission process of offshore wind power, this paper proposes a three-frequency transformer which enables the output of 50 Hz at the input of 50/3 Hz excitation. In this paper, the magnetic flux of a three-dimensional wound core transformer is analytically modeled, the existing condition of magnetic flux harmonics of a three-dimensional wound core transformer is analyzed, the distribution of harmonic content in magnetic flux is obtained, and the principle of realizing frequency conversion is expounded. Secondly, the finite element analysis of the frequency converter is carried out. Finally, a prototype of a frequency transformer is made and tested to verify the correctness of the proposed scheme.

Failure Criteria for Brittle Notched Specimens

Recently, new failure criteria were proposed for brittle materials to predict their failure loads regardless of the shapes of a notch or a crack in the material. This paper is to further evaluate the failure criteria for different shapes of notches and different materials. A circular hole, elliptical hole or crack-like slit with a different angle with respect to the loading direction was considered. Double circular holes were also studied. The materials studied were an isotropic material like polymethyl methacrylate (PMMA) as well as laminated carbon fiber composites. Both cross-ply and quasi-isotropic layup orientations were examined. The lamination theory was used for the composite materials so that they can be modelled as an anisotropic and homogeneous material. The test results were compared to the theoretical predictions using the finite element analysis with 2-D plane stress models. Both theoretical failure stresses agreed well with the experimental data for the materials and notch geometries studied herein.

Geometric parameters optimization of a two-dimensional phoxonic crystal with dual forbidden band characteristics

In this paper, a novel phoxonic crystal (PxC) structure composed of silicon, with optimal dual phononic band gap (PNBG) and photonic band gap (PTBG), is presented. Using the finite element analysis method, both the transmission characteristics and dispersion relation of PNBG and PTBG are calculated, and the existence of dual BGs is demonstrated by the means of the analysis of transmission for the PxC structure. The influences of structural parameters on the dual forbidden band characteristics are further explored, the sensitive structure parameters can be determined: the width of elastic beams, the length of square silicon, and the length of square hole. Using the orthogonal test, 25 experimental runs based on 3-factor and 5-level experiment are performed to finish the numerical experimental design and analysis. Four functional relationships can be acquired between the three sensitive parameters and dual BGs. Finally, the unified objective function method is employed to perform the construction of the single objective optimization model for the purpose of obtaining the optimal dual BGs and the corresponding optimal parameter combinations of the PxC structure. Such scheme can be used as the potential optimization way, which may find wide application in the development and design of PxCs.

Numerical Study on Plastic Strain Distributions and Mechanical Behaviour of a Tube under Bending

Tubular pipe structures have been used in various applications—domestic, aviation, marine, manufacturing and material testing. The applications of tubular pipes have been considered greatly in the installation of tubular pipes, marine risers and pipe bending. For the investigation of plastic strains and the mechanical behaviour of a tube under bending, considerations were made utilising an exponent model with assumptions on the plane strain. The bending moment, wall thickness effect, cross-sectional distribution, stresses during bending and neutral layer boundaries were all presented as necessary theoretical formulations on the physics of tubular pipe bending. This model was based on the analytical and numerical investigation. In principle, the application can be observed as the spooling of pipes, bending of pipes and reeling. Comparisons were made on two models developed on the finite element analysis in Simscale OpenFEA, namely the linear-elastic and the elasto-plastic models. This study presents visualization profiles using plastic strain to assess its effect on the tubular pipes. This can increase due to the limitation of plastic deformation on the composite materials selected.

Evaluation of a Suitable Material for Soft Actuator Through Experiments and FE Simulations

Soft actuators are generally built to achieve extension, contraction, curling, or bending motions needed for robotic or medical applications. It is prepared with a cylindrical tube, braided with fibers that restrict the radial motion and produce the extension, contraction, or bending. The actuation is achieved through the input of compressed air with a different pressure. The stiffness of the materials controls the magnitude of the actuation. In the present study, Silastic-P1 silicone RTV and multi-wall carbon nanotubes (MWCNT) with reinforced silicone are considered for the evaluation. The dumbbell samples are prepared from both materials as per ASTM D412-06a (ISO 37) standard and their corresponding tensile strength, elongation at break, and tensile modulus are measured. The Ogden nonlinear material constants of respective materials are estimated and used further in the finite element analysis of extension, contraction, and bending soft actuators. It is observed that silicone RTV is better in high strain and fast response, whereas, silicone/MWCNT is better at achieving high actuation.

Research on Lightweight of Docking Structure Based on ANSYS

The docking structure has broad application prospects in the construction of tower assembly. However, the docking structure has a relatively large quality, which has a greater impact on the operations of high-altitude workers. This paper studies the impact force on docking structure during the docking process. The finite element analysis (FEA) model of the docking structure and the tower section is established and the impact force of the docking structure under various wording conditions is calculated. Based on the calculation results of the impact force the lightweight research of the docking structure is carried out and the optimization constraint conditions are proposed. The simulation model is established by ANSYS and the optimization design of guiding tools and vertical limit tools are completed by adjusting the structural parameters. After the optimization design, the docking structure is trial-produced and tested. Through the method of FEA and experiment, a butting device that meets the requirements of strength and rigidity and is lighter in weight is obtained. Compared with the existing docking structure, the weight of the optimized docking structure is reduced by about 39%. The research results can provide a reference for the design of the docking structure.