Natural fibers and their composites are the evolving movements in material science, and with that, the utmost use of plant-based fibers has become the focus of this research. Sisal and cotton natural fibers were used to construct a prosthetic socket as an attempt to substitute material currently available in the manufacturing of sockets. The vacuum bagging technique was adopted to produce a below-knee socket. The influence of different fiber layering sequences on the volumetric and mechanical characteristics was estimated experimentally and numerically. Mechanical tensile tests were used to assess laminated specimens, such as tensile strength, young modulus, and elongation percentage. The number and type of reinforcing layers had an effect on mechanical properties, and the best composite specimens were three layers of sisal with two layers of carbon fiber, with tensile strength and modulus of elasticity reaching (261–4760) MPa, respectively. The finite element method (ANSYS-16.1) was used to anatomize by seeing the contours distribution of safety factor, equivalent Von Mises stress, equivalent Von Mises strain, and total deformation. This procedure was executed by building ten models for the socket, which served as three-dimensional structural composite materials. The results of the present study advocate that the arrangement of natural and synthetic reinforcements allow the preparation of bio-composites with enhanced performance. This work revealed the assets of sisal and cotton fiber hybrid reinforced PMMA resin composites (hybridized at diverse volume percentages and lamination layup), which have not been tried up to now.
To renovate the form and the lost roles of people with limb amputation, artificial limbs, also known as prostheses, are often used [
War, land mines, and the main usual tragedies, for instance, earthquakes and deluges, in addition to chronic illnesses, including vascular infections, for example, diabetic difficulties, arteriosclerosis, and thrombosis are altogether donating aspects to the universal request for prostheses [
In recent years, there have been countless developments in the design and usage of materials in socket production. Typical sockets are made by entrenching various films of perlon stockinet fibers, woven carbon fabric, and a PMMA polymer resin. These conventional materials originate from non-sustainable bases, along with generating irritant radiation from harmful gases and dust. Consequently, it needed costly professional health and safety equipment. The socket is made from resin and natural fibers intended to improve mechanical strength and durability [
The researchers who studied this field (Oleiwi et al.) [
The outcomes of our experiments where we surveyed the probability of creating a lower prosthetic limb socket made from renewable resources were presented. This paper considers hybrid fiber-reinforced polymer matrix composites (a mix of natural and synthetic fibers). The hybrid fiber reinforcements in the composites can endure greater loads associated with single-fiber reinforcements in a diverse path proven on the reinforcement, and the contiguous matrix keeps them in the preferred position and orientation, performing as a greater load transfer medium between them.
The focus was to first recognize suitable resin polymer and natural fiber arrangements by conducting a series of tests. The test sockets that were prepared to use stockinet woven were from the best fiber. The goal is to prove that prosthetic limb sockets can be built from renewable, safe resources without conceding the strength of these composite materials.
This section describes the materials, equipment, and preparation stages of socket manufacturing which could supply helpful mechanical features. Also, describe the details of the mechanical and morphological tests.
Materials used in the below-knee lamination socket for this research are sisal and cotton fibers, which were made by (Changzhou Doris Textile Co., Ltd., China) as a woven mat. They were dipped in a 5% NaOH solution for about two hours at room temperature. After the alkaline treatment, sisal and cotton fibers were thoroughly washed by running water so the fiber is stronger and more durable and achieves better bonding with matrix materials.
The additional materials needed are unidirectional carbon fabric (a type of carbon reinforcement that is non-woven and features all fibers running in a single, parallel direction, manufactured by Otto Bock Company, China), glass fiber (manufactured by Otto Bock Company, China), Perlon stockinet (item name from the company is (623T5), manufactured by Otto Bock Company, China), lamination resin: Polymethyl methacrylate (PMMA), hardening powder (Otto Bock Health Care 617P37), polyvinyl.
A positive Jepson mold with a rectangular figure and a size of 25 × 20 × 10 cm3. The vacuum forming system includes a vacuum pump and diverse kinds of stands, pipes, and tubes. A digital vernier and a sensitive weighing device for measuring the dimension and weight of samples. The mechanical workshop was done in the university’s technical training and the workshop center includes different gears for cutting by CNC machine.
The masses of reinforcement and matrix material are calculated based on the obligatory volume fractions. Specimens were prepared by the vacuum modeling procedure as shown in
No. of Lamination | Total No. of layers | Lamination lay-up | Lamination layup procedures | Poison’s ratio |
---|---|---|---|---|
Lamination 1 | 5 | 4 Perlon+1 Cotton (1CO) | (2P+1CO+2P) layers | 0.355 |
Lamination 2 | 6 | 4 Perlon+2 Cotton (2CO) | (2P+2CO+2P) layers | 0.353 |
Lamination 3 | 7 | 4 Perlon+3 Cotton (3CO) | (2P+3CO+2P) layers | 0.356 |
Lamination 4 | 9 | 4 Perlon+3 Cotton+2 Carbon (COC) | (2P+1CO+1C+1CO+1C+1CO+2P) layers | 0.335 |
Lamination 5 | 9 | 4 Perlon+3 Cotton+2 Fiber Glass(COG) | (2P+1CO+1G+1CO+1G+1CO+2P) layers | 0.272 |
Lamination 6 | 5 | 4 Perlon+1 Sisal (1S) | (2P+1S+2P) layers | 0.43 |
Lamination 7 | 6 | 4 Perlon+2 Sisal (2S) | (2P+2S+2P) layers | 0.342 |
Lamination 8 | 7 | 4 Perlon+3 Sisal (3S) | (2P+3S+2P) layers | 0.334 |
Lamination 9 | 9 | 4 Perlon+3 Sisal+2 Carbon (SC) | (2P+1S+1C+1S+1C+1S+2P) layers | 0.339 |
Lamination 10 | 9 | 4 Perlon+3 Flax+2 Fiber Glass (SG) | (2P+1S+1G+1S+1G+1S+2P) layers | 0.283 |
The tensile investigation was employed to reach a stress-strain curve aimed at each laminated composite sample. This curve is applied to obtain tensile characteristics of these specimens, such as tensile strength (UTS), elastic modulus (E), and elongation percentage at the break. The tensile test is performed following the (ASTM D638-03 type IV standard) [
The broad analysis by utilizing ANSYS has three discrete stages; the first step is constructing the geometry as a model and the second step stratifying the boundary conditions load and reaching the solution, then the third step reviewing the results [
In this work, with the aid of ANSYS Workbench 16.1 software, finite element analysis (FEM) was used as a numerical tool to imitate a prosthetic socket of 75.5 kg in body mass. The socket is examined at the riskiest load situations, which occur at heel strike during the gait cycle. Pressures in
Site | Anterior | Medial | Posterior | Lateral | Basal |
---|---|---|---|---|---|
Average pressure value (kPa) | 100 | 80 | 90 | 65 | 288 |
The meshing process has been completed by selecting the volume then the profile of the element was appointed as a tetrahedron (Automatic meshing) as shown in
This investigation relates the tensile characteristics (Young’s modulus, Ultimate tensile strength, and percentage of elongation at break) of trans-tibial composite prosthetic sockets. Altering the nature of reinforcement has an excessive impact on tensile properties.
Young’s modulus is a measure of the stiffness of a part.
The percentage of elongation-at-break value was estimated to see the effect of fiber content on the ductility of the composite specimens. The increase in the number of sisal and cotton reinforcing layers led to a reduction in the elongation percentage values for samples [
Numerical analysis is executed to find the values of stresses produced in the parts of the socket due to the generation of the interface pressure between the socket and the muscles and body weight during walking. The equivalent von-Mises Stresses analysis gave us knowledge of the amounts of stress and spread in the socket and the deformation generated by the interface pressure in the socket. The results displayed that the highest value of stress produced in the socket was presented with Lamination 6 (2 Perlon+1 Sisal+2 Perlon) layers (equivalent to (26.83 MPa)) and placed at the center of the anterior side in the tibia bone while the sides (posterior, medial, and lateral) partake pressure that is less than the anterior side
From
These are counterplots concerning mechanical failure at a specified design life. In Ansys, the highest value of safety factor shown is 15, but when the stress in a precise location develops greater than the strength of the material, the safety factor ratio develops inferior to 1, and with this, there is a risk which is mainly that in an exact part of the model, the stress is greater than the strength the material can stand and failure is projected earlier in the design life [
The deformation investigation supplied us with information on the values and location of the overall behavior of the socket. The maximum deformation value of the socket can be seen in Lamination 1 (2 Perlon+1 Cotton+2 Perlon) equal to (9.058) mm for the model manufactured, whereas the lowest extent of total deformation can be perceived in Lamination 9 (2 Perlon+1 Sisal+1 Carbon+1 Sisal+1 Carbon+1 Sisal+2 Perlon) at (3.19) mm.
Based on the results, the prosthesis socket archetype prepared from lamination materials can be considered as a substitute artifact that could be employed by the patients with harmless and contented intent, in addition to having an optimistic influence on the usage of natural materials that are ecologically friendly and can be reused. The main findings of this study are as follows: The physical properties: hybrid (Cotton Glass) reinforcement having the highest density and thickness and volume fraction. There is a prodigious consequence in the tensile strength and modulus of elasticity of the socket with varying its material, where the (strength/density) ratio, Young’s modulus (E), and ultimate tensile strength of the stacking arrangement (4 Perlon–3 Sisal−2 Carbon fiber) where the tensile strength and modulus reach (261 MPa and 4.76 GPa), respectively. The highest percentage of elongation values was obtained with three cotton fibers and two layers of fiberglass, at 7.9%. The results showed that (sisal+Carbon reinforcement) composites offered the best experimental, numerical consequences which brand them as the outstanding contender to advance the mechanical features of the trans-tibial prosthetic socket.
The authors would like to express thanks to all the staff at the Faculty of Engineering at the University of Technology–Baghdad as well as the staff of Ibtisam Center of an Artificial Limb.