Strength testing of low-cost 3D-printed transtibial prosthetic socket

2021 ◽  
pp. 095441192110600
Author(s):  
Merel van der Stelt ◽  
Luc Verhamme ◽  
Cornelis H Slump ◽  
Lars Brouwers ◽  
Thomas JJ Maal
Keyword(s):  
Tensile Properties ◽  
Lower Limb ◽  
Low Cost ◽  
Test Method ◽  
Structural Testing ◽  
International Standard ◽  
Prosthetic Socket ◽  
Computer Aided ◽  
3D Printed ◽  
Lower Limb Prostheses

Measurement and production of traditional prosthetic sockets are time-consuming, labor-intensive, and highly dependent on the personnel involved. An alternative way to make prostheses is using computer-aided design (CAD) and computer-aided manufacturing (CAM). Fused Filament Fabrication (FFF) may be an alternative to make low-cost prosthetic sockets. This study investigates the tensile properties of potential printing materials suitable for FFF according to ISO527 (Standard Test Method for Tensile Properties of Plastics). To ensure that FFF-printed sockets are safe for patient usage, the structural integrity of the 3D-printed prosthesis will be investigated according to ISO10328 (International Standard Structural Testing of Lower Limb Prostheses). Tough PLA was the most suitable print material according to ISO 527 testing. The Tough PLA printed socket completed 2.27 million cycles and a static test target value of 4025 N. Future research remains necessary to continue testing new potential materials, improve print settings, and improve the socket design for the production of FFF-printed transtibial prosthetic sockets. FFF using Tough PLA can be used to create transtibial prostheses that almost comply with the International Standard for Structural Testing of Lower Limb Prostheses.

3D-printed polypropylene transtibial sockets: Mechanical behavior

2020 ◽  
pp. 095440622094392
Author(s):  
MacArthur L Stewart
Keyword(s):  
3D Printing ◽  
Yield Strength ◽  
Tensile Test ◽  
Tensile Properties ◽  
Material Properties ◽  
Standard Test ◽  
Test Method ◽  
Material Behavior ◽  
Cross Sectional ◽  
3D Printed

This paper defines the tensile properties of a successfully worn 3D-printed transtibial socket. The socket was printed from a proprietary polypropylene filament and FDM 3D-printing process. Fused disposition modeling involves producing successive cross-sectional layers on top of one another and welding them together. Because of this, a notch is formed between the printed layers. As part of this investigation, tensile test specimens were die-cut perpendicular to the material direction and tested according to ASTM D638—Standard Test Method for Tensile Properties of Plastics. From the measured load–elongation data, stress–strain curves and the corresponding material properties were determined, including modulus of elasticity E, Poisson’s ratio ν, yield strength Sy, and ultimate strength Su. The average values for each of these material properties were 955 MPa, 0.35, 11.4 MPa, and 16.3 MPa, respectively. In addition to defining tensile properties, this work demonstrated a viable methodology for characterizing the as-built material behavior of 3D-printed sockets.

scholarly journals A Cost-Effective Inertial Measurement System for Tracking Movement and Triggering Kinesthetic Feedback in Lower-Limb Prosthesis Users

Sensors ◽  
2021 ◽  
Vol 21 (5) ◽  
pp. 1844
Author(s):  
McNiel-Inyani Keri ◽  
Ahmed W. Shehata ◽  
Paul D. Marasco ◽  
Jacqueline S. Hebert ◽  
Albert H. Vette
Keyword(s):  
Lower Limb ◽  
Balance Control ◽  
Low Cost ◽  
Feedback System ◽  
Inertial Measurement ◽  
Upper Limb Prosthesis ◽  
Kinesthetic Feedback ◽  
Kinesthetic Illusion ◽  
Limb Prosthesis ◽  
Lower Limb Prostheses

Advances in lower-limb prosthetic technologies have facilitated the restoration of ambulation; however, users of such technologies still experience reduced balance control, also due to the absence of proprioceptive feedback. Recent efforts have demonstrated the ability to restore kinesthetic feedback in upper-limb prosthesis applications; however, technical solutions to trigger the required muscle vibration and provide automated feedback have not been explored for lower-limb prostheses. The study’s first objective was therefore to develop a feedback system capable of tracking lower-limb movement and automatically triggering a muscle vibrator to induce the kinesthetic illusion. The second objective was to investigate the developed system’s ability to provide kinesthetic feedback in a case participant. A low-cost, wireless feedback system, incorporating two inertial measurement units to trigger a muscle vibrator, was developed and tested in an individual with limb loss above the knee. Our system had a maximum communication delay of 50 ms and showed good tracking of Gaussian and sinusoidal movement profiles for velocities below 180 degrees per second (error < 8 degrees), mimicking stepping and walking, respectively. We demonstrated in the case participant that the developed feedback system can successfully elicit the kinesthetic illusion. Our work contributes to the integration of sensory feedback in lower-limb prostheses, to increase their use and functionality.

scholarly journals Loads in hip disarticulation prostheses during normal daily use

1998 ◽  
Vol 22 (3) ◽  
pp. 199-215 ◽  
Author(s):  
M. Nietert ◽  
N. Englisch ◽  
P. Kreil ◽  
G. Alba-lopez
Keyword(s):  
Lower Limb ◽  
Real Life ◽  
Test Methods ◽  
Structural Testing ◽  
Uneven Surface ◽  
Hip Prostheses ◽  
Draft Standard ◽  
Everyday Situation ◽  
Level 2 ◽  
Lower Limb Prostheses

As a result of deficiency at birth, disease or trauma, there are people who have no limbs from the hip joint downwards. These people have no possibillity of locomotion without the use of other devices such as wheelchairs or hip disarticulation prostheses. As these prostheses are used by people of all ages, people who are different in their grade of physical activities and their weights, the prostheses are subject to different stresses related to these different circumstances. The European Level 2 Draft Standard prEN 12523: 1966 “External limb prostheses and external orthoses — requirements and test methods” contains strength requirements for lower limb prostheses. These requirements shall be verified, where appropriate, by the application of the International Standard ISO 10328 “Prosthetics — Structural testing of lower limb prostheses” and ISO/FDIS 15032 “Prosthetics: Structural testing of hip prostheses”. In order to allow the prostheses to be tested to the stresses that are experienced in real life, it is necessary to measure the stress that is induced in the prostheses while the patient is in an everyday situation, such as walking on level floor, walking on grass and/or walking on an uneven surface. This work is concerned with the acquisition of loads generated in hip units of hip disarticulation prostheses by amputees during various activities. More than 30 patients were tested in Germany, France, and Belgium. The measurements were carried out with financial support from the European Commission and coordinated by the secretariat of CEN TC 293.

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