A new method for theoretical analysis of static indentation test

Sakamoto, Makoto; Li, Guoan; Hara, Toshiaki; Chao, Edmund Y.S.

doi:10.1016/0021-9290(95)00120-4

Cited by 44 publications

References 20 publications

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“…In this formulation, for thick-layer problems, the valid solutions can be calculated iteratively, but for thinlayer ones, they only can be solved numerically. In the 3D linear elasticity context, Sakamoto et al (1996) proposed a closed-form series solution for the contact problem with a finite thickness elastic layer, and Yoffe (1984) extended the Hertz theory for wider contact problems. However, both of them are only suitable for rigid indenters.…”

Section: Introductionmentioning

confidence: 99%

Analytical parametric analysis of the contact problem of human buttocks and negative Poisson's ratio foam cushions

Wang

Lakes

2002

International Journal of Solids and Structures

103

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Analytical investigations on the contact problems between two homogeneous and isotropic soft bodies were performed to simulate the contact of human buttocks and seat cushions. The cushion materials' Poisson's ratio were allowed to be negative. The human buttocks were modeled as an ideal sphere with radius 15 cm, and assumed to have a low Young's modulus and a Poisson's ratio close to 0.5. These parameters were held constant during our analysis. Peak contact pressure was reduced by adjusting the contour curvature of cushions according to Hertz theory, as expected. Moreover, analysis by both the Hertz model and a finite thickness 3D elasticity model showed that using negative Poisson's ratio cushions could further reduce the pressure. Negative Poisson's ratio cushions may be beneficial in the prevention of pressure sores or ulcers in the sick and in reduction of pressure-induced discomfort in seated people.

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Section: Introductionmentioning

confidence: 99%

Analytical parametric analysis of the contact problem of human buttocks and negative Poisson's ratio foam cushions

Wang

Lakes

2002

International Journal of Solids and Structures

103

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“…Indentation testing can be employed to determine the material properties such as the Poisson's ratio for the material under the indenter; however, the theoretical and computational ramifications are formidable. 6,7 Nonetheless, application of the conditions under which indentation testing is valid can be applied to the evaluation of the test sites to determine material stiffness. 8 Mechanical Figure 1.…”

Section: Methodsmentioning

confidence: 99%

Cranial defect repair using e-PTFE: Part I. Evaluation of bone stiffness

Valdevit

Türegün

Kambic

et al. 2000

J. Biomed. Mater. Res.

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Autologous bone grafts are the preferred material for craniofacial reconstruction, but such procedures lead to increased operative time and bleeding, donor site morbidity, and graft resorption. The efficacy of expanded-polytetrafluoroethylene (e-PTFE) sheets to increase bone regeneration and remodeling in cranial defects using a rabbit model was evaluated by mechanical testing. New Zealand white rabbits were divided into 3 groups and sacrificed 6 months after surgery. In the Split Table group, (n = 16), a bilateral bone defect was created on the outer table of the parietal bones. In the Full Table group, (n = 16), a bilateral defect was created through both the inner and outer table of the cranium. The control group, (n = 10) was subjected to a sham operation. Indentation testing was performed to determine the stiffness of newly formed bone in and around the defect. Near the center of the defect, Split Table defects repaired with e-PTFE resulted in significantly stiffer bone than regenerated control bone. The Full Table defects repaired with e-PTFE also resulted in bone significantly stiffer than control regenerated bone around the central region of the defect. The data supports the hypothesis that e-PTFE improves the repair of cranial defects in a rabbit model. It is surmised that the porosity of the e-PTFE provides a stable scaffold for migration of tissue regenerating cells, which may be preferentially localized near the cranial suture lines. This porosity may also provide a barrier to fibrous tissue regenerating cells.

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“…For thick-layer problems, the solutions can be calculated iteratively, but for thin layer ones, the problem can be solved numerically. A closed-form series solution for the contact problem with a finite thickness elastic layer was proposed by Sakamoto et al (1996).…”

Section: Introductionmentioning

confidence: 99%

Comparison of Contact Stress Distribution for Foam Seat and Seat of Auxetic Spring Skeleton

Janus-Michalska

Jasińska

Smardzewski

2013

International Journal of Applied Mechanics and Engineering

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The objective of this paper is to present and compare the results of numerical solutions of contact problem for two types of seats subjected to typical sitting loadings. The first seat is made of a typical hyperelastic foam, the other is designed with an auxetic polyamid spring skeleton. Computer simulations of the seat structure under a typical static loading exerted by a human body are performed by means of ABAQUS FEA. The model provides an insight into deformation modes and stress field in relation to geometric and material parameters of the seat structure.The other type of seat, due to the fact of global auxecity and progressive springs characteristics reduces contact stress concentrations, giving an advantegous distribution of pressure and provides the sensation of physical comfort. The proper seat skeleton shape leads to an improvement of ergonomic quality.

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A new method for theoretical analysis of static indentation test

Cited by 44 publications

References 20 publications

Analytical parametric analysis of the contact problem of human buttocks and negative Poisson's ratio foam cushions

Analytical parametric analysis of the contact problem of human buttocks and negative Poisson's ratio foam cushions

Cranial defect repair using e-PTFE: Part I. Evaluation of bone stiffness

Comparison of Contact Stress Distribution for Foam Seat and Seat of Auxetic Spring Skeleton

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