Studies on tensile and tear fracture of the S8210 tarpaulin

The tarpaulin of PVC-coated S8210 wagons is a composite textile membrane. This material is resistant to atmospheric factors (wind, rain, snow, etc.), durable for many practical applications and can be manufactured in various colors and prints. PVC membrane material is inexpensive, soft and easy to manufacture. These materials are widely used in large-opening spatial structures due to excellent mechanical behavior and beautiful textures. The tarpaulins are made by the method of welding with high frequency currents from the material S8210. In the present paper, the tensile and tearing mechanical properties of tarpaulins intended to protect goods carried by railway wagons are presented. The results of this study can be used in establishing the appropriate utilization of the fabric, in accordance to the warp and weft directions

Analytical model for computing translational and rotational angular momentum occurring in treadmill walking

The kinematical modifications of human gait associated with treadmill walking are well studied in the literature. Fewer researches are focusing on computing the dynamical parameters of the gait, in this particular situation. Starting from kinematical data recorded in treadmill walking, the paper proposes an analytical model of the lower limbs that allows computation of translational and rotational angular momentum for each segment. The experimental data used in the study were recorded using ultrasound based, 3D motion equipment. By mean of this system, relative and absolute angles of the lower limb can be computed using Cartesian coordinates of each anatomical landmark. The velocities and accelerations were obtained by numerical derivative. In order to compute the dynamical parameters, segment masses and inertias were collected from the literature. The masses are based on percentage of total body weight while the segment inertias are based on geometrical characteristics of lower limb segments

Influence of Manufacturing Parameters on Mechanical Properties of Porous Materials by Selective Laser Sintering

This paper presents a study on the tensile properties of Alumide and polyamide PA2200 standard samples produced by Additive manufacturing (AM) based on selective laser sintering (SLS). Because of the orthogonal trajectories of the laser beam during exposure, different orientations of the samples may lead to different mechanical properties. In order to reveal this process issue, four orientations of the samples in building envelope were investigated. For data reliability, all the other process parameters were constant for each material and every orientation. The tensile tests highlight small differences in elastic properties of the two materials, while significant differences in strength properties and energy absorption were observed. Nevertheless, Young modulus indicates high stiffness of the Alumide comparing to PA2200 samples. The stereo microscopy reveals a brittle fracture site for Alumide and a ductile fracture with longitudinal splitting zones for PA2200. From the orientation point of view, similar properties of samples oriented at 0 and 90 degrees for all investigated mechanical properties were observed. However, tensile strength was less influenced by the sample orientations

Correlations between Process Parameters and Outcome Properties of Laser-Sintered Polyamide

As additive manufacturing (AM) becomes more accessible, correlating process parameters with geometric and mechanical properties is an important topic. Because the number of process variables in AM is large, extensive studies must be conducted in order to underline every particular influence. The study focuses on two variables—part orientation in the orthogonal horizontal plane and energy density—and targets two outcomes—geometric and tensile properties of the parts. The AM process was conducted on selective laser sintering (SLS) machine EOS Formiga P100 using EOS white powder polyamide (PA2200). After finishing the sinterization process, the parts were postprocessed, measured, weighted, and mechanically tested. The geometric evaluation and mass measurements of every sample allowed us to compute the density of all parts according to the sinterization energy and orientation, and to determine the relative error of every dimension. By conducting the tensile testing, the elastic and strength properties were determined according to process variables. A linear trend regarding sample density and energy density was identified. Also, large relative dimensional errors were recorded for the lowest energy density. Mechanical properties encountered the highest value for the highest energy density at a 45° orientation angle

FATIGUE DEVICE FOR TESTING ANKLE JOINT ENDOPROSTHESES

The paper proposes a model of a fatigue device for testing dedicated to ankle prostheses. The concept of the testing device relies on two aspects: almost any type of ankle prosthesis can be tested on it and it has to work on INSTRON axial-torsion testing machine. Starting from these requirements, a 3D functional assembly that reproduces the real movement of the ankle joint during gait cycle has been designed. The device is based on a cam-follower mechanism

FEA STUDY FOR THE MECHANICAL STRENGTH EVALUATION OF SELF-ADHESIVE CEMENTS USED FOR THE RESTORATION OF INTEGRAL CERAMIC INLAYS

Aim. The purpose of this study is to evaluate the strength of the adhesion of ceramic inlays (IPS max Press-Ivoclar) in 3 different clinical situations, while comparing the clinical performance of two different luting materials (Variolink Esthetic DC - Ivoclar and Maxcem Elite – Kerr). Materials and methods. The image processing was done using the Mimics 10 software. The purpose of the processing was to transform the 2D image collection into a volume representing the structure of a molar. After the reconstruction, using the SolidWorks 2013 CAD modeling program, geometric operations were performed to obtain three types of inlays. Three directions of stress have been chosen and they have been preserved for all 3 situations: the direction (Δ1) simulates a normal traction on the inlay, the direction (Δ3) simulates a shear stress, and the direction (Δ2) a combined oblique stress. The load forces modules were 90 and 230 N. Finite element analysis was performed with FEA Ansys 13 software. Results. Both types of luting cements have higher resistance values than the values recorded at both the surface and the interface. This indicates that either of the two application rates applied in any of the three directions will not damage any of the two types of luting materials. Due to the occurrence of shear stresses, in the case of iC inlay, the horizontal stress exceeds the value of the mechanical strength of cement for the accidental stress of 230 N, but neither in this case there will be no damage. Conclusion. Variolink II has better adhesion properties than Maxcem cement, which is why, regardless of the geometric configuration, the direction of the application force and the modulus used in the simulation, the adhesion of Variolink has higher mechanical strength