Bacterial cellulose (BC) is a natural polymer with properties suitable for tissue engineering and possible applications in scaffold production. However, current procedures have limitations in obtaining BC pellicles with the desired structural, physical, and mechanical properties. Thus, this study analyzed the optimal culture conditions of BC membranes and two types of processing: draining and oven-drying. The aim was to obtain BC membranes with properties suitable for a wound dressing material. Two studies were carried out. In the preliminary study, the medium (100 mL) was inoculated with varying volumes (1, 2, 3, 4, and 5 mL) and incubated statically for different periods (3, 6, 9, 12, and 18 days), using a full factorial experimental design. Thickness, uniformity, weight, and yield were evaluated. In the optimization study, a Box–Behnken design was used. Two independent variables were used: inoculum volume (X1: 1, 3, and 5 mL) and fermentation period (X2: 6, 12, and 18 d) to determine the target response variables: thickness, swelling ratio, drug release, fiber diameter, tensile strength, and Young’s modulus for both dry and moist BC membranes. The mathematical modelling of the effect of the two independent variables was performed by response surface methodology (RSM). The obtained models were validated with new experimental values and confirmed for all tested properties, except Young’s modulus of oven-dried BC. Thus, the optimal properties in terms of a scaffold material of the moist BC were obtained with an inoculum volume of 5% (v/v) and 16 d of fermentation. While, for the oven-dried membranes, optimal properties were obtained with a 4% (v/v) and 14 d of fermentation.

Expanded polystyrene (EPS) is used in a variety of applications due to its characteristics, light weight, good thermal insulation and durability. Expanded polystyrene, when used to insulate buildings, undergoes various mechanical stresses, such as: compression stresses, bending stresses, dynamic stresses or shock stresses. This paper presents the results of three-point compression and bending tests for four types of polystyrene (EPS-50, EPS-80, EPS-100 and EPS-120) at different speeds. Based on the data resulting from the compression tests, the theoretical mathematical model was determined, which can be used both for determining the theoretical mechanical characteristics and for modelling the EPS properties in numerical simulations.

Bacterial cellulose (BC) is a natural polymer with properties suitable for tissue engineering and possible applications in scaffold production. However, current procedures have limitations in obtaining BC pellicles with the desired structural, physical, and mechanical properties. Thus, this study analyzed the optimal culture conditions of BC membranes and 2 types of processing: draining and oven-drying. The aim was to obtain BC membranes with properties suitable for a wound dressing material. Two studies were carried out. In the preliminary study the medium (100 mL) was inoculated with varying volumes (1; 2; 3; 4; and 5 mL) and incubated statically for different periods (3; 6; 9; 12; and 18 days), using a full factorial experimental design. Thickness, uniformity, weight, and yield were evaluated. In the optimization study, a Box–Behnken design was used. Two independent variables were used: inoculum volume (X1: 1; 3; and 5 mL) and fermentation period (X2: 6; 12; and 18 d) to determine the target response variables: thickness, swelling ratio, drug release, fiber diameter, Tensile strength, and Young's Modulus for both dry and moist BC membranes. The mathematical modelling of the effect of the 2 independent variables was accomplished by response surface methodology (RSM). The obtained models were validated with new experimental values, and confirmed for all tested properties, except Young Modulus of oven-dried BC. Thus, the optimal properties in terms of a scaffold material of the moist BC were obtained with an inoculum volume of 5% (v/v) and 16 d of fermentation. While, for the oven-dried membranes a 4% (v/v) and 14 d of fermentation.

This paper presents three methods of converting complex 3D models of STL type into solid models. For converting the STL models, specific approximation functions from CATIA and Creo Parametric software were used as well as 3D solid modeling methods that used sketches drawn for sections of the specific analyzed model. This conversion is required to get a solid 3D model that can be used for finite element analysis and to be processed using Boolean functions in specific CAD programs. This paper also presents a study of the effectiveness of FEA in respect to the time required for the analysis of each converted model. The analyzed STL files contain data obtained by computer tomography and are the 3D models of the human orthopedic system: the left zygomatic bone and upper part of the right femur. The presented conversion methods can be used by design engineers both in medical applications (where the complexity of forms is well known) for the design of implants and for industrial applications for reverse engineering.

The purpose of these studies was to improve the design and manufacturing process by selective laser melting, of new medical implants. After manufacturing process, the implants were measured, microscopically and mechanical analyzed. Implants manufactured by AM can be an attractive option for surface coatings to improve the osseointegration process. The main advantages of customized implants made by AM process are: the precise adaptation to the region of implantation, better cosmesis, reduced surgical times and better performance over their generic counterparts. These medical manufacturing changes the way that the surgeons are planning surgeries and engineers are designing custom implant. AM process has eliminated the constraints of shape, size, internal structure and mechanical properties making it possible for fabrication of implants that conform to the physical and mechanical requirements of implantation according to CT images. This article will review some custom implants fabricated in DME using biocompatible titanium.

Abstract.A finite element analysis software has been used in order to determine several mechanical properties for samples made from unidirectional composite materials. Plates from reinforced unidirectional fiber glass polymer composites obtained by compression hand lay-up process were studied.Tensile tests were performed upon samples with different number and orientation of the composite ply layup.

No abstract

In the recent years, the electric vehicles have drawn great attention worldwide as a feasible solution for clean transportation. The charging infrastructure for electric vehicles is expanding throughout the world, encouraged by large investments from the automotive industry, to reduce carbon emissions. The purpose of this paper is to design the shell of an electrical vehicle charger by using polymeric composite materials. The manufacturing technology is proposed and the analysis of the product behaviour during the wind action in extreme conditions is presented. The paper includes studies and research regarding the design, the manufacturing and the simulation for the action of wind upon the product�s walls. The simulations are performed for the actual used material (ordinary sheet steel) and for the proposed composite material in order to compare the results. The composite material seems to be an adequate solution for the electric charger shell.