Biomechanics. Mechanical Properties of Living Tissues

Fung, Y. C.; Skalak, Richard

doi:10.1115/1.3162171

Cited by 2,530 publications

(2,948 citation statements)

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“…All the composites exhibited properties which were within the range of the flexural properties of cortical bones (E = 5-23 GPa, σ = 35-280 MPa) [30,31]. It is well known that the strength of the fibre/matrix interface is critical to the mechanical properties of fibre reinforced composites [9,[32][33][34].…”

Section: Discussionmentioning

confidence: 70%

In-situ polymerisation of fully bioresorbable polycaprolactone/phosphate glass fibre composites: In vitro degradation and mechanical properties

Chen

Parsons

Felfel

et al. 2016

Journal of the Mechanical Behavior of Biomedical Materials

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Fully bioresorbable composites have been investigated in order to replace metal implant plates used for hard tissue repair. Retention of the composite mechanical properties within a physiological environment has been shown to be significantly affected due to loss of the integrity of the fibre/matrix interface. This study investigated phosphate based glass fibre (PGF) reinforced polycaprolactone (PCL) composites with 20%, 35% and 50% fibre volume fractions (Vf) manufactured via an in-situ polymerisation (ISP) process and a conventional laminate stacking (LS) followed by compression moulding. Reinforcing efficiency between the LS and ISP manufacturing process was compared, and the ISP composites revealed significant improvements in mechanical properties when compared to LS composites. The degradation profiles and mechanical properties were monitored in phosphate buffered saline (PBS) at 37°C for 28 days. ISP composites revealed significantly less media uptake and mass loss (p<0.001) throughout the degradation period. The initial flexural properties of ISP composites were substantially higher (p<0.0001) than those of the LS composites, which showed that the ISP manufacturing process provided a significantly enhanced reinforcement effect than the LS process. During the degradation study, statistically higher flexural property retention profiles were also seen for the ISP composites compared to LS composites. SEM micrographs of fracture surfaces for the LS composites revealed dry fibre bundles and poor fibre dispersion with polymer rich zones, which indicated poor interfacial bonding, distribution and adhesion. In contrast, evenly distributed fibres without dry fibre bundles or polymer rich zones, were clearly observed for the ISP composite samples, which showed that a superior fibre/matrix interface was achieved with highly improved adhesion.

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Section: Discussionmentioning

confidence: 70%

In-situ polymerisation of fully bioresorbable polycaprolactone/phosphate glass fibre composites: In vitro degradation and mechanical properties

Chen

Parsons

Felfel

et al. 2016

Journal of the Mechanical Behavior of Biomedical Materials

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“…Generally, the mechanical properties of human tissues are non-linear [17]. In simple terms, this means that the stress-strain curve is not a straight line.…”

Section: Limitations Of the Test Methodsmentioning

confidence: 99%

Stiffness gradient in the crystalline lens

Weeber

Eckert

Pechhold

et al. 2007

Graefes Arch Clin Exp Ophthalmol

141

147

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Background While the overall stiffness of the lens has been measured in a number of studies, the knowledge about the stiffness distribution within the lens is still limited. The purpose of this study was to determine the stiffness gradient in the human crystalline lens. A secondary purpose was to determine whether the stiffness gradient depends on age. Methods The local dynamic stiffness was measured in 10 human crystalline lenses (age range: 19 to 78 years). The lenses were stored at −70°C before being measured. The influence of freezing on the mechanical properties has been determined in a previous study. A small oscillating probe was used to measure the local dynamic shear modulus as a measure of lens stiffness. The measurements were taken in the cross-sectional plane through the lens equator. Results The local dynamic shear modulus varied with location for all tested lenses. The central stiffness of the oldest lens (78 years) was 10 4 times higher than the youngest (19 years) lens. The equatorial stiffness of the oldest lens was 10 2 times higher than the youngest lens. For the older lenses, the centre was 5.8-210 times stiffer than the periphery, as opposed to earlier results described by Fisher (1971), who found that the periphery was up to 3 times softer than the centre for lenses younger than 70-years-old. For the three youngest lenses (19 to 49 years), the periphery was 2.2-16.6 times stiffer than the centre. Conclusions The dynamic stiffness of the crystalline lens varies with location within the lens. The stiffness gradient depends on the age of the lens. The results of the 10 lenses indicate that the stiffness of both centre and periphery increase with age, but at a different rate.

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“…For 0 < [NaOH] < [AcH], that is, before the stoichiometric point is reached, we obtain the following solution: (6) where (7) and (8) For [NaOH] > [AcH], that is, after the stoichiometric point is reached, the solution is: (9) where (10) Both pH-equations (equations 6 and 9) only depend on two parameters, [AcH] and [NaOH], both of which are determined by the FEM simulations. The equations are implemented in a Matlab ® program in order to calculate the pH at every specific position in the considered microfluidic device, resulting in a graphical representation of the pH distribution (see figure 4a-c).…”

Section: Evolution Of a Ph Gradient In The Microchannelsmentioning

confidence: 99%

An In Situ Study of Collagen Self-Assembly Processes

et al. 2007

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We present in situ studies on the self-assembly and dynamic evolution of collagen gels from semidilute solutions in a microfluidic device. Collagen fibrils not only reinforce the mechanical properties of bone and tissues, but they also influence cellular motility and morphology. We access the initial steps of the hierarchical self-assembly of collagen fibrils and networks by using hydrodynamic focusing to form oriented fibers. The accurate description of the conditions within the microchannel requires a numerical expression for the pH in the device, as well as a modified mathematical description of the viscosity, which increases nearly 300-fold as collagen fibrils form around neutral pH. Finite element modeling profiles overlay impressively with crossed polarized microscopy images of the birefringent fibrils in the channel. Real-time X-ray microdiffraction measurements in flow indicate an enhanced supramolecular packing having a unit spacing commensurate with that of a pentameric collagen subunits. These results have significant implications for the field of biomedicine, wherein new aligned, cellularly active, and mechanically strengthened materials continue to be in demand. However, this work is also remarkable from a more fundamental, biophysical point of view, since the underlying concepts may be generalized to a large pool of systems.

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Biomechanics. Mechanical Properties of Living Tissues

Cited by 2,530 publications

References 0 publications

In-situ polymerisation of fully bioresorbable polycaprolactone/phosphate glass fibre composites: In vitro degradation and mechanical properties

In-situ polymerisation of fully bioresorbable polycaprolactone/phosphate glass fibre composites: In vitro degradation and mechanical properties

Stiffness gradient in the crystalline lens

An In Situ Study of Collagen Self-Assembly Processes

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