Material characterisation of additively manufactured elastomers at different strain rates and build orientations

Abayazid, Fady F.; Ghajari, Mazdak

doi:10.1016/j.addma.2020.101160

Cited by 35 publications

(47 citation statements)

References 65 publications

(92 reference statements)

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“…The data provided ( Dykstra et al, 2019 ) can be used to define a Neo-Hookean strain energy potential and a three-term Prony series. To the best of our knowledge, the most comprehensive series of mechanical experiments and analyses of A30 and T+ to date were provided by Abayazid and Ghajari ( Abayazid and Ghajari, 2020 ). Uniaxial large-strain tension and compression experiments were performed to investigate the time-independent material behavior.…”

Section: Introductionmentioning

confidence: 99%

“…Furthermore, time dependency was studied and modeled by means of uniaxial high-frequency and relaxation loadings. The material model parameters provided ( Abayazid and Ghajari, 2020 ) can be used directly to define a three-term Ogden strain energy potential in combination with a five-term Prony series.…”

Section: Introductionmentioning

confidence: 99%

“…We present a novel, functionally integrated rotary bellows actuator that is suitablefor 3D inkjet printing to a make an early foray into this unexplored field of actuators. In preparation for the simulation of its time-dependent structural behavior, we calibrated a suitable hyperviscoelastic material model, which we validated and compared to material models from recent publications ( Slesarenko and Rudykh, 2018 ; Dykstra et al, 2019 ; Abayazid and Ghajari, 2020 ) using a bellows stress relaxation experiment as published by Dämmer et al ( Dämmer et al, 2019a ). The time-dependent structural behavior of our rotary actuator was then investigated in experiments and corresponding FE simulations.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Design of an Inkjet-Printed Rotary Bellows Actuator and Simulation of its Time-Dependent Deformation Behavior

et al. 2021

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State-of-the-art Additive Manufacturing processes such as three-dimensional (3D) inkjet printing are capable of producing geometrically complex multi-material components with integrated elastomeric features. Researchers and engineers seeking to exploit these capabilities must handle the complex mechanical behavior of inkjet-printed elastomers and expect a lack of suitable design examples. We address these obstacles using a pneumatic actuator as an application case. First, an inkjet-printable actuator design with elastomeric bellows structures is presented. While soft robotics research has brought forward several examples of inkjet-printed linear and bending bellows actuators, the rotary actuator described here advances into the still unexplored field of additively manufactured pneumatic lightweight robots with articulated joints. Second, we demonstrate that the complex structural behavior of the actuator’s elastomeric bellows structure can be predicted by Finite Element (FE) simulation. To this end, a suitable hyperviscoelastic material model was calibrated and compared to recently published models in a multiaxial-state-of-stress relaxation experiment. To verify the material model, Finite Element simulations of the actuator’s deformation behavior were conducted, and the results compared to those of corresponding experiments. The simulations presented here advance the materials science of inkjet-printed elastomers by demonstrating use of a hyperviscoelastic material model for estimating the deformation behavior of a prototypic robotic component. The results obtained contribute to the long-term goal of additively manufactured and pneumatically actuated lightweight robots.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Design of an Inkjet-Printed Rotary Bellows Actuator and Simulation of its Time-Dependent Deformation Behavior

et al. 2021

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“…[21] This enables multimaterial objects to be built up and, in some cases, tens of thousands of nozzles can be used to extrude the raw polymers which are then combined prior to polymerization leading to tailorable material properties. [114,115]…”

Section: From Hand-crafting To Advanced Manufacturingmentioning

confidence: 99%

Past, Present, and Future of Soft‐Tissue Prosthetics: Advanced Polymers and Advanced Manufacturing

et al. 2020

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past 30 years, [12,13] it is only the last decade that has seen its rapid development as part of the fourth industrial revolution. [14] This change in practice is evidenced by the significant fraction of recent literature describing advances in 3D printed prostheses, including technological advances [4,15-18] and clinical reports. [19,20] Further innovations involving collaborations between clinicians, academics, and industry, promise even greater capabilities. The future will see 3D printers that can mix materials as desired during fabrication [21] and those that can 3D print organic semiconductors and piezoelectric polymers for sensing and bionics [22-24] (Figure 1). This report is focused on polymers for soft tissue, external, personalized, prosthetics with clinical applications for the ear, [25] nose, [26] eye, [27] face, [28] breast, [29] and hand. [30] The characteristics of both traditional and 3D printable polymeric materials, as well as current advanced manufacturing technologies and those in development, are also reviewed. The earliest evidence of prosthetics dates back to ≈2300 BC, where Egyptian mummies have been discovered with eye, nose, and genital reconstructions fashioned from plaster packed with mud, sand, linen, butter, or soda (Figure 1). [31] Wood, cloth, natural waxes, resins, and metals were later used as the material of choice for rudimentary prostheses. [32] Prostheses remained relatively unchanged for thousands of years until the 16th century, where prosthetic noses and eyes were made from parchment, wax, wood, hard rubber, gold, silver, and copper. [33] Metals continued as a fundamental material throughout the 19th century, largely due to their ability to be shaped and molded as needed. [34,35] One of the first polymers to be used in prosthetics, poly(methyl methacrylate) (PMMA), was developed in response to the glass shortages in the World Wars of the 20th Century. [36] This polymer went on to become the most common prosthetic material of the time, and still finds use today in artificial eyes [33] and prosthetic substructures. [37] Further innovations in the 20th century produced many new polymers, such as vinyls, copolymers, plastisols, and one of the most significant materials in prosthetics, silicone. [38] Discovered in the early 1900s by Fredrick Kipping, silicone was first used in prosthetics by George W Barnhart in 1960. [39] This versatile polymer remains a primary prosthetic material today due to its soft tissue-like properties, ease of manipulation, chemical inertness, durability, and excellent biocompatibility. [40,41] The search for alternative materials Millions of people worldwide experience disfigurement due to cancers, congenital defects, or trauma, leading to significant psychological, social, and economic disadvantage. Prosthetics aim to reduce their suffering by restoring aesthetics and function using synthetic materials that mimic the characteristics of native tissue. In the 1900s, natural materials used for thousands of years in prosthetics were replaced by syntheti...

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“…Better quality models, more choice of materials, multi-material and multi-color printing, controlling the flexibility of final part, and easier post-processing are the unique benefits of this technology compared to other AM techniques. 50,51 In PolyJet machines, ultraviolet light cures the jet layers of liquid photopolymer resins from the bottom up and incorporates multiple materials into a single print. The nominal size of the build volume is 260 × 260 × 200 mm in X, Y, and Z planes respectively.…”

Section: Machine Materials and Softwarementioning

confidence: 99%

Design and development of model eye for retina laser by using additive manufacturing

Pugalendhi¹,

Ranganathan²,

Narendran

et al. 2020

Proc Inst Mech Eng H

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Surgical skill of the surgeon can be improved by surgical simulation. Especially in ophthalmology, it is impossible to use real human/non-human primate eyes for ophthalmology surgery practice. However, surgical practice is most important for ophthalmologist. The retina laser surgery is one of the ophthalmology surgeries and it requires more surgical practice for surgeons to use the laser beam precisely to coagulate and fuse small areas of tissue. Dealing with the prospect of vision reduction or vision loss presents a peculiar problem and that can be highly stressful and frustrating for both doctors and patients. In this regard, training for indirect ophthalmoscopy and retinal photocoagulation is undergone using model eyes instead of real eyes. Properties and functioning of an existing model eye are huge and they differ from real human eye such as casings are completely rigid and focusing of retinal fundus is not completely covered. Therefore, this research concentrates to develop a model eye that assimilates close to the human eye by focussing on the maximum viewing area that is not done at the moment. Finally, the design and development of re-engineered model eye for retina laser is fabricated by additive manufacturing. Compared to existing plastic model eye, viewing area and viewing angle of the re-engineered model eye is increased by 16.66% and 6.14%, respectively. Due to design modifications and elimination of the insert, it can be reduced by 18.99% and 13.95% of height and weight of the top casing respectively. Developed re-engineered model eye will improve the surgical and diagnostic skill of the surgeon and increase their confidence and proficiency. It also augments the effective use of essential ophthalmic instruments. Additionally, it can reduce the surgical error and meet the existing demand of actual eyes for surgical practices.

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Material characterisation of additively manufactured elastomers at different strain rates and build orientations

Cited by 35 publications

References 65 publications

Design of an Inkjet-Printed Rotary Bellows Actuator and Simulation of its Time-Dependent Deformation Behavior

Design of an Inkjet-Printed Rotary Bellows Actuator and Simulation of its Time-Dependent Deformation Behavior

Past, Present, and Future of Soft‐Tissue Prosthetics: Advanced Polymers and Advanced Manufacturing

Design and development of model eye for retina laser by using additive manufacturing

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