A variational constitutive model for soft biological tissues

Sayed, Tamer El; Mota, Alejandro; Fraternali, Fernando; Ortiz, Michael

doi:10.1016/j.jbiomech.2008.02.023

Cited by 73 publications

(41 citation statements)

References 29 publications

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“…is expected to be strongly non-convex (Ogden et al, 2004) and well suited for genetic algorithms (Schmitt, 2004;El Sayed et al, 2008). We employ the Breeder Genetic Algorithm (BGA) presented in De Falco et al (1996) and successfully used as a parameter identification tool in Fraternali et al (2010).…”

Section: Section 52 Fitting Of Experimental Results On Compressed Cmentioning

confidence: 99%

Multiscale mass-spring models of carbon nanotube foams

Fraternali

Blesgen

Amendola

et al. 2011

Journal of the Mechanics and Physics of Solids

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Section: Section 52 Fitting Of Experimental Results On Compressed Cmentioning

confidence: 99%

Multiscale mass-spring models of carbon nanotube foams

Fraternali

Blesgen

Amendola

et al. 2011

Journal of the Mechanics and Physics of Solids

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“…Our aim was to characterize the influence of these fibers on the surface instability and folding. Each layer of tissue was modeled as a compressible neoHookean material, although our computational formulation extends easily to more sophisticated tissue models [9]. Throughout this study we have ignored both plastic deformation and viscoelastic relaxation of the tissue since the measured relaxation times for soft tissue (seconds) are typically much faster than the timescale of growth (weeks/months).…”

Section: Discussionmentioning

confidence: 99%

Wrinkling, creasing, and folding in fiber-reinforced soft tissues

Stewart

Waters

Sayed

et al. 2016

Extreme Mechanics Letters

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Many biological tissues develop elaborate folds during growth and development. The onset of this folding is often understood in relation to the creasing and wrinkling of a thin elastic layer that grows whilst attached to a large elastic foundation. In reality, many biological tissues are reinforced by fibres and so are intrinsically anisotropic. However, the correlation between the fiber directions and the pattern formed during growth is not well understood. Here, we consider the stability of a two-layer tissue composed of a thin hyperelastic strip adhered to an elastic half-space in which are embedded elastic fibers. The combined object is subject to a uniform compression and, at a critical value of this compression, buckles out of the plane -it wrinkles. We characterize the wrinkle wavelength at onset as a function of the fiber orientation both computationally and analytically and show that the onset of surface instability can be either promoted or inhibited as the fiber stiffness increases, depending on the fibre angle. However, we find that the structure of the resulting folds is approximately independent of the fiber orientation. We also explore numerically the formation of large creases in fiber-reinforced tissue in the post-buckling regime.

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“…Furthermore, when studying soft tissue properties, elastoplastic responses and viscoelastic mechanisms, authors suggest different mechanical intrinsic properties of three cranial structures: gray matter (GM), white matter (WM), and brain stem with corpus callosum (BSCC). [6] Thus, data offered for the long-term shear modulus (elastoplastic response) are 6.80 kPa for GM, 8.20 kPa for WM and 11.60 kPa for BSCC. [6] The same source also offers different figures for the initial shear modulus for all three of these rather schematic divisions of the central nervous system, which might correspond, in an approximate form, to the cortex (GM), to the corona radiata, with the subcortical and periventricular areas (WM), and to the central-midline structures (BSCC).…”

Section: Case Reportmentioning

confidence: 99%

“…[6] Thus, data offered for the long-term shear modulus (elastoplastic response) are 6.80 kPa for GM, 8.20 kPa for WM and 11.60 kPa for BSCC. [6] The same source also offers different figures for the initial shear modulus for all three of these rather schematic divisions of the central nervous system, which might correspond, in an approximate form, to the cortex (GM), to the corona radiata, with the subcortical and periventricular areas (WM), and to the central-midline structures (BSCC). Thus, albeit authors generally agree that the brain and spinal cord move as a unit when exposed to a sagittal rotational acceleration of the head and neck, [7] our case suggests that a different momentum might exist, mainly during the deceleration that follows the abrupt cessation of an angular head motion, creating an important shear factor between the cortical-external structures and the BSCC on the other side.…”

Section: Case Reportmentioning

confidence: 99%

Rotational head trauma with callosal contusion and C6 fracture: a high-speed motorcycle accident

Vyshka¹,

Troshani²,

Bozaxhiu³

et al. 2013

Ulus Travma Acil Cerrahi Derg

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Bu yazıda, yüksek hızla motosiklet sürerken dört tekerli bir araca çarpmış 34 yaşındaki bir Arnavut erkeği olgusu sunuldu. Çarpma anında havada ekseni etrafında üç kez dön-dükten sonra motosikletinden yere düşen olgu, daha sonra derin koma klinik tablosuyla yoğun bakım ünitesinde, bilincine yeniden kavuşana kadar dokuz gün tedavi edilmiş ve uzun dönemli rehabilitasyon prosedürleri uygulanmış. Manyetik rezonans ve bilgisayarlı tomografi görüntüleri rotasyonel kafa travması açısından çok aydınlatıcıydı. Gerçekten kafatası kırıkları olmaksızın birden fazla kallozal kanama odağına ilaveten C6 vertebrasında lineer kompleks kırık hattı izlenmekteydi. Bu olgu boyun omurgasını hareketsiz durumda tespit edip ortopedik tedavi uygulanmaya uygundu. Rotasyonel açısal akselerasyonun diffüz beyin ve/veya aksonal hasarına neden olan önemli bir nedensel faktör olduğu görünmektedir. Doğrudan kafatasına gelen darbenin etyolojik önemi tartışma konusuysa da asla gö-zardı edilmemelidir.Anahtar Sözcükler: Aksonal travma; beyin travması; rotasyonel açısal akselerasyon; trafik kazası.We present the case of a 34-year-old Albanian male who was riding a motorcycle when he collided at high-speed with a four-wheel vehicle. After a triple pivotal rotation in the air at the moment of impact, he fell from the motorcycle to the ground. The clinical picture thereafter was one of deep coma, treated in the intensive care unit for nine days, until he regained consciousness and long-term rehabilitation procedures were put in place. The magnetic resonance and computed tomography images were very illustrative of a rotational head trauma mechanism, since in addition to multiple callosal hemorrhages and the lack of cranial fractures, a linear complex fracture of the C6 vertebra was seen, justifying orthopedic treatment through immobilization of the cervical spine. Rotational angular acceleration seems to be an important causative factor toward provoking diffuse brain and/or axonal injury; the etiological importance on the direct skull impact is controversial, but in any case not negligible.Key Words: Axonal injury; brain trauma; rotational angular acceleration; traffic accident. CASE REPORTA 34-year-old male (height 176 cm, weight 85 kg) was riding his motorcycle on a secondary rural road in central Albania when the motorcycle collided at high speed with a four-wheel drive vehicle. According to witnesses, the injured person was wearing a helmet and was driving approximately 50 km/hr. At the site of the accident, tracks on the ground indicating a triple pivotal rotation of the motorcycle were evident. The injured lost consciousness immediately at the site of the collision; the driver of the car causing the crash and other witnesses accompanied the patient to the nearest hospital.Upon arrival, he was in a deep coma (Glasgow Coma Scale score: 5 points) with flexion provoked only by painful stimuli; an anisocoria with left but reactive mydriasis was present. The patient was otherwise stable from the hemodynamic point of view. He was admitted in the Intensive...

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A variational constitutive model for soft biological tissues

Cited by 73 publications

References 29 publications

Multiscale mass-spring models of carbon nanotube foams

Multiscale mass-spring models of carbon nanotube foams

Wrinkling, creasing, and folding in fiber-reinforced soft tissues

Rotational head trauma with callosal contusion and C6 fracture: a high-speed motorcycle accident

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