9—a Study of Needled Fabrics. Part Ii: Effects of the Needling Process

Hearle, J. W. S.; Sultan, Mufti Amir; Choudhari, T. N.

doi:10.1080/00405006808659970

Cited by 54 publications

(27 citation statements)

References 1 publication

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“…Needling density is a manufacturing parameter that has been extensively studied (cf. Hearle and co-workers [14, 15, 52]) and demonstrated to modulate the effective length of fiber segments and crimp amplitude, and consequently influence the fiber behavior at in micro-scale and bulk properties of the scaffold. While scaffold mechanical response can be quantified and determined directly from experiments, the fiber behavior cannot and a modeling framework is the tool that transfers the measurable experimental data into microstructural insight.…”

Section: Discussionmentioning

confidence: 99%

A mathematical model for the determination of forming tissue moduli in needled-nonwoven scaffolds

2017

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Formation of engineering tissues (ET) remains an important scientific area of investigation for both clinical translational and mechanobiological studies. Needled-nonwoven (NNW) scaffolds represent one of the most ubiquitous biomaterials based on their well-documented capacity to sustain tissue formation and the unique property of substantial construct stiffness amplification, the latter allowing for very sensitive determination of forming tissue modulus. Yet, their use in more fundamental studies is hampered by the lack of (1) substantial understanding of the mechanics of the NNW scaffold itself under finite deformations and means to model the complex mechanical interactions between scaffold fibers, cells, and de novo tissue; and (2) rational models with reliable predictive capabilities describing their evolving mechanical properties and their response to mechanical stimulation. Our objective is to quantify the mechanical properties of the forming ET phase in constructs that utilize NNW scaffolds. We present herein a novel mathematical model to quantify their stiffness based on explicit considerations of the modulation of NNW scaffold fiber-fiber interactions and effective fiber stiffness by surrounding de novo ECM. Specifically, fibers in NNW scaffolds are effectively stiffer than if acting alone due to extensive fiber-fiber cross-over points that impart changes in fiber geometry, particularly crimp wavelength and amplitude. Fiber-fiber interactions in NNW scaffolds also play significant role in the bulk anisotropy of the material, mainly due to fiber buckling and large translational out-of-plane displacements occurring to fibers undergoing contraction. To calibrate the model parameters, we mechanically tested impregnated NNW scaffolds with polyacrylamide (PAM) gels with a wide range of moduli with values chosen to mimic the effects of surrounding tissues on the scaffold fiber network. Results indicated a high degree of model fidelity over a wide range of planar strains. Lastly, we illustrated the impact of our modeling approach quantifying the stiffness of engineered ECM after in vitro incubation and early stages of in vivo implantation obtained in a concurrent study of engineered tissue pulmonary valves in an ovine model.

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Section: Discussionmentioning

confidence: 99%

A mathematical model for the determination of forming tissue moduli in needled-nonwoven scaffolds

2017

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“…The decrease of basis weight is caused by the expansion of the web induced by the spreading of fibers by the needle. 1 Conversely, the decrease of thickness is mainly a result of compression of the web structure along the ND. As the fibers on the top surface of web are punched into the interior by the needle, the web is compressed by the frictional force between the needle-punched fibers.…”

Section: Resultsmentioning

confidence: 99%

“…An obvious tensile strength increase caused by the insertion of ND-oriented fibers was also reported by Hearle and co-workers. 1,9 They also pointed out that the amount of ND-oriented fibers should be related to the amount of fibers bearing the tensile force. However, they stopped at the qualitative level because they had no way to analyze the structure quantitatively.…”

Section: Resultsmentioning

confidence: 99%

“…The tensile strength (N/tex) was calculated from the obtained breaking load per unit width divided by the basis weight of each sample. 1,3…”

Section: Methodsmentioning

confidence: 99%

“…9,10 Moreover, these fiber bundles passed through the bottom of the fabric and were connected to each other along the machine direction (MD) of the fabric, making a stitch structure. 1,3 These structures are important because along with the bridging fibers they are thought to bear external force applied to the fabric. External force is also applied to the loop or pillar structures through the bridging fibers or stitch structure, and they bear the force of the friction between needle-punched fibers.…”

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confidence: 99%

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Structure analysis of needle-punched nonwoven fabrics by X-ray computed tomography

Ishikawa

Ishii

Nakasone

et al. 2017

Textile Research Journal

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Needle-punching conditions determine the structure of nonwoven fabrics and the structure determines their tensile properties. However, the structural parameters of nonwoven fabrics and the relationship between these parameters and tensile properties have not been quantitatively analyzed. Therefore, we analyzed the structure of needle-punched nonwoven fabrics by X-ray computed tomography (XCT). The relationships between the needle-punching conditions, tensile properties, and structural parameters, such as fiber-volume fraction and three-dimensional fiber orientation, were investigated. The fiber-volume fraction in the middle layer of the fabric was clearly larger than that of the bulk above a compression ratio of 1.4. With increasing needle penetration depth, the fibers tended to become oriented both parallel and perpendicular to the normal direction of the fabric plane while avoiding the intermediate direction. A linear relationship was found between the obtained volume fraction of fibers oriented in the normal direction and the tensile strength of the fabric. These results demonstrate that XCT image analysis is effective to evaluate the structure of needle-punched nonwoven fabrics and to design the properties of nonwoven fabrics.

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Needlepunched Composite Structures

Seyam

2012

Wiley Encyclopedia of Composites

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This article describes the formation of preforms using needlepunching technology, which is a mechanical bonding technique, and the prior processes (carding, carding and crosslapping, and air lay) that may be used to form fiberwebs. The impact of processing variables and needle parameters on the needled preform properties, which influence the final composite performance, is reviewed. Methods of resin infusion that are required to convert needled preforms to final composites are given along with their features. Finally, applications of needlepunched composites are provided with their constituent and competitive approaches.

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9—a Study of Needled Fabrics. Part Ii: Effects of the Needling Process

Cited by 54 publications

References 1 publication

A mathematical model for the determination of forming tissue moduli in needled-nonwoven scaffolds

A mathematical model for the determination of forming tissue moduli in needled-nonwoven scaffolds

Structure analysis of needle-punched nonwoven fabrics by X-ray computed tomography

Needlepunched Composite Structures

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