Search

The impact of the addition of the nanofiller – halloysite – on the mechanical, physicochemical and biological properties of a nanocomposite, in which thermoplastic polyurethane fulfilled the role of the matrix was investigated. The nanocomposite was obtained by extrusion in three variants with 1, 2 and 3 wt % halloysite. The nanostructure of the obtained materials was confirmed using Atomic Force Microscopy (AFM). Based on the mechanical tests carried out, it was proven that the obtained nanocomposites were characterized by a tensile modulus greater than the polyurethane constituting the matrix. The density and hardness of the nanocomposites had changed within error limits compared to unmodified polyurethane. Biological tests showed no cytotoxicity of all the tested materials to normal human dermal fibroblasts (NHDF). Degradation tests were carried out in artificial plasma and showed that samples with 2 wt % halloysite addition had the best ratio of tensile strength and elongation at break to elasticity modulus.

The purpose of the conducted study was to analyse new materials intended for contact with the human body in view of their physical, chemical and biological properties. The authors have put to test six commercially available materials, four out of which were composite polyamide 12-based materials, while two were polyurethanes. The examined materials were assessed in terms of the surface. Subsequently, their hardness and biocompatibility were tested. The authors devoted major attention to the tests of absorption and emissivity of water, the pH = 7.4 PBS buffer solution and pH = 4.3 artificial sweat in temperatures of 21°C and 37°C. The results of the tests have confirmed the non-toxicity of all the tested materials and allowed to provide their characteristics in terms of their surface, hardness, as well as absorption and emissivity of various body fluids. Both polyamide 12 and the tested polyurethanes are classified as thermoplastics that may be used in additive technology.

Eco-friendly composites are proposed to substitute commonly available polymers. Currently, wood–plastic composites and natural fiber-reinforced composites are gaining growing recognition in the industry, being mostly on the thermoplastic matrix. However, little data are available about the possibility of producing biocomposites on a silicone matrix. This study focused on assessing selected organic fillers’ impact (ground coffee waste (GCW), walnut shell (WS), brewers’ spent grains (BSG), pistachio shell (PS), and chestnut (CH)) on the physicochemical and mechanical properties of silicone-based materials. Density, hardness, rebound resilience, and static tensile strength of the obtained composites were tested, as well as the effect of accelerated aging under artificial seawater conditions. The results revealed changes in the material’s properties (minimal density changes, hardness variation, overall decreasing resilience, and decreased tensile strength properties). The aging test revealed certain bioactivities of the obtained composites. The degree of material degradation was assessed on the basis of the strength characteristics and visual observation. The investigation carried out indicated the impact of the filler’s type, chemical composition, and grain size on the obtained materials’ properties and shed light on the possibility of acquiring ecological silicone-based materials.

Nowadays, conveyor belts with synthetic fabric made of multilayered composite materials are used in many industries. The dimensions of these devices are usually large, which makes maintenance work more difficult. Install or dismantle of conveyor belts in these devices is carried out sporadically. Because of that belt assembly devices are often overlooked during the construction process of the conveyor. This means that conveyor belts are often lifted through various types of chains or steel profiles. Due to the length of the belts, their weight is often very high. This may result in conveyor belts being damaged during install or dismantle. The paper focused on analyzing the stress distribution in composite conveyor belt depending on the way how it is lifted. Numerical analysis was performed in commercially available software based on finite element method. Two cases of lifting a belt with a weight of 2.5 tons have been compared. Based on the obtained results, recommendations were made on how to install or dismantle conveyor belts in large-sized conveyor.

The aim of this study is a practical analysis of the innovative yet non-invasive use of a method obtaining complex human and animal limb geometry on the basis of human and animal limb with its main goal to develop a personalized prosthesis. The hereby article presents an overview of widely known and used external evaluation methods as well as inner limb stump geometry for the sake of fabrication of upper and lower limb prosthesis. A different approach has been presented to limb geometry modeling which is featured by a great shortening of time with a patient due to the use of alginate mass. Because of a lack of possibilities to get limb stump geometry, in the experiment a healthy human and animal limbs were used. The methodology to get a complex human and animal limb shape, presented in this article, involves in the first place the realization of negative cast with the use of alginate mass and secondly positive cast with the use of plaster. The following stages of work include healthy limb 3D scanning and 3D printing in order to make a real-life model.

One of the most popular meshless methods in engineering applications is SPH method, broadly used in the simulation of cutting process and fluid-structure interaction. Examples of this method usage, by a module implemented in the commercial software LS Dyna, are presented by authors. They are compared with experimental tests. In this publication are presented experimental and numerical results from observing the behaviour of the bodies during impact with water. The need to study this phenomenon resulted during the design process of an angler fishing float, which was developed and applied for patent protection by one of the co-authors. For this purpose, a station composed of a transparent water-filled tank attached to a force sensor was created and the numerical model was prepared. Bodies in the form of a SPHere, cube, cylinder, and cone of a constant volume of one litre each were immersed in water at a constant displacement of 100 mm, represented by a quadrant of sinus function at frequencies of 0.5 Hz, 1 Hz, 2 Hz and 3 Hz. The test was performed on a dynamic endurance machine manufactured by MTS 858 Table Top System. Parellely was developed the numerical model with water as SPH elements. Numerical analysis was performed on the mpp (massively parallel processor) version of LS Dyna R11 with the use of 3 nodes and 10 processors per node. Principles of the SPH method implemented in LS Dyna are described in the literature. The purpose of this article was to determine the influence of the body shape immersed in water on the value of the load recorded on the force transducer at the base of the tank. Additionally, estimation of the influence of frequency on loads was to notice. The paper presents the results of experimental studies, which were then compared with the results of numerical simulation.

This article presents preliminary research in designing overlays and insoles for footwear with measurement components located in the mid-foot and the heel area. With this type of measurement components, the gait can be analysed in any place of the room that was designated for this examination. With measurement components used in separate components, the gait can be measured in its different phases. With additive manufacturing technology, the device designed can be quickly verified.

Halloysite nanotube (HNT) additions to the thermoplastic polyurethane (TPU) system were thoroughly evaluated in this study. The resultant composites have been designed for future personalized intervertebral disc implant applications, which requires additional technology to obtain the appropriate geometry unique to each patient. These requirements can be fulfilled using 3D printing. In this work, a technology was developed to produce filaments for fused deposition modeling (FDM). Nanocomposites were prepared using variable HNT content (1, 2, and 3 wt.%). The nanostructure of the resultant composites was confirmed using scanning transmission electron microscopy (STEM). Mechanical tests were used to measure the tensile modulus, stress, and elongation the composites and TPU matrix. Nanocomposites with 2% HNT content were able to withstand 26% increased stress and 50% increased elongation compared to pure TPU before fracturing in addition to a 13% reduction in the friction coefficient. A MTT cytotoxicity assay confirmed the cytotoxicity of all tested materials against human epidermal keratinocyte cells (HaCaT).

As part of the experiments herein, the mechanical properties of specimens made of poly-ether-ether-ketone (PEEK) material using 3D printing technology were determined. Two populations of specimens were investigated, the first of which contained an amorphous structure, while the other held a crystal structure. The studies also investigated the influence of the print directionality on the mechanical properties obtained. Static tensile, three-point bending, and impact tests were carried out. The results for the effect of the structure type on the tensile properties showed that the modulus of elasticity was approximately 20% higher for the crystal than for the amorphous PEEK form. The Poisson’s ratios were similar, but the ratio was slightly higher for the amorphous samples than the crystalline ones. Furthermore, the studies included a chemical PEEK modification to increase the hydrophilicity. For this purpose, nitrite and hydroxyl groups were introduced into the chain by chemical reactions. The results demonstrate that the modified PEEK specimens had worse thermoplastic properties than the unmodified specimens.

The article presents a motion dynamics model of a sample military special vehicle, two suspension control algorithms and the results of three different numerical experiments that have been conducted. The applied measure of appraisal was the comparison of the amplitudes of displacement, speed and acceleration – both linear (in the vertical direction) and angular (in the longitudinal and transverse planes) in time.

The article presents results of the anthropometric hand design. It describes its kinematic chain and mechanical structure. Furthermore the ranges of motion for specific joints are being shown. Moreover, examples of other mechanical hand solutions are being presented.

The EOD technicians work in an environment with a higher threat. The job of the EOD technicians is to assist in identification of explosive ordnance and its destruction at the place of finding. Their working environment is influenced by physical, chemical, physiological and psychological factors. The main threats are injuries, illnesses, and work traumas resulting from explosions. To reduce the risk of blast injuries the protective bomb suits are used by the technicians. In the article results of experimental research assessing threat of EOD technicians from explosive blast are presented. Upper limbs are the most exposed to injuries in the work of pyrotechnic technicians. In the article the acceleration test results of upper limb are presented. During the research an acceleration of the particular body parts as well as pressure acting on the thoracic of the dummy surrogate were measured. The test was conducted in open air condition in Krupski Mlyn area. Essential elements of the research were to develop and use proper devices for data acquisition in a test condition of blast. During the test the prototype autonomous measurement system developed in the Institute of Theoretical and Applied Mechanics was used. The results of the experimental research will be used to design and improve better personnel blast protection suits as well as educational materials for the future EOD technicians.

Magnetorheological materials (MR fluids) are a class of smart materials whose rheological properties (e.g. viscosity) may be rapidly varied by applying a magnetic field. Under influence of magnetic field the suspended magnetic particles interact to form a structure that resists shear deformation or flow. This process takes only a few (1–10 ms) and magnetorheological fluid rapidly changes its viscosity.

In the article, a methodology for assessing blast threat of Explosive Ordnance Disposal (EOD) technicians was presented. During the research tests of controlled explosion were performed with the dummy mounted to simulate standing position. The response of the dummy against different improvised explosive materials with the charge of 75 g to 1000 g was performed. During the research an acceleration of the particular body part (head, pelvis, upper and lower limb) as well as pressure acting on the dummy was measured. The article deals with the protection of EOD technicians against such threats as an overpressure, a heat and shock wave. Results of the experimental research will be used to design and improve better personnel blast protection suits as well as educational materials for the future EOD technicians. Even when using a well characterized, widely available explosive, a mine explosion still exhibits an element of variability from one test to the next.