Viscoelastic Behavior of Open Cell Foams

Gent, A. N.; Rusch, K. C.

doi:10.5254/1.3544850

Cited by 34 publications

(23 citation statements)

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“…A hyperbolic form of the force deflection dependence was selected. The hyperbolic form was first proposed by Gent and Rusch [16,17].…”

Section: (2)mentioning

confidence: 99%

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Validation of a Nonlinear Automotive Seat Cushion Vibration Model

Patten¹,

Pang

1998

Vehicle System Dynamics

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A low-order, lumped parameter model is proposed to describe the vertical vibration compliance of an automotive seat. The model includes nonlinear stiffness and damping effects that mimic the properties exhibited by open cell foams that are commonly used in the construction of an automotive seat cushion. A shaped sandbag was positioned on a seat cushion and vibrated to obtain test data. White noise acceleration with amplitude ranging from 0.05 g rms to 0.45 g rms in increments of 0.05 g rms was used to excite the seat track. A luxury car seat and a sports car seat were tested and a nonlinear seat model was identified that predicts the actual test data with fidelity. The paper demonstrates that once a family of model parameters is identified for a particular seat, then the model can be used for a wide spectrum of seat track inputs. Additional experiments also verified that when the sandbag mass was increased by as much as 50%. the predicted response using the proposed model was in agreement with the measured response. Finally, the paper reports the result of an experiment using a human subject on a seat cushion. A simulation using the new cushion model and an IS0 vibration model of a seated human produced response data that was very similar to the actual test data.

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“…A hyperbolic form of the force deflection dependence was selected. The hyperbolic form was first proposed by Gent and Rusch [16,17].…”

Section: (2)mentioning

confidence: 99%

“…A model was chosen that included linear damping and a quadratic flow loss associated with the motion of the air through the foam matrix. The damping model; was adopted that is based on previous investigations of polyurethane foam damping by Hilyard [IS], Liber and Epstein [18] and Gent with Rusch [16,17]. We assume here that C , is a constant.…”

Section: (2)mentioning

confidence: 99%

Validation of a Nonlinear Automotive Seat Cushion Vibration Model

Patten¹,

Pang

1998

Vehicle System Dynamics

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“…Post processing to reticulate the foam, or remove/puncture the thin membranes between pore cells while leaving the net-like foam backbone intact 8 , will likely enable blood flow to more easily permeate throughout the foam, and allow for a forming clot to stabilize the device within the aneurysm. This permeation of blood throughout the material also enables the desired cellular components necessary to induce healing to more easily migrate into the volume of foam after clotting has occurred.…”

Section: Introductionmentioning

confidence: 99%

“…Reticulation has been achieved by multiple post-processing methods within industry, including caustic leaching 8 via exposure of the foam to a caustic bath for a specific amount of time, temperature and speed, thermal reticulation via a controlled burning of the membranes with the ignition of hydrogen and oxygen gases within a vessel housing the foam, or cyclic loading and unloading of the material. The act of reticulation changes the overall physical properties of foam.…”

Section: Introductionmentioning

confidence: 99%

Reticulation of low density shape memory polymer foam with an in vivo demonstration of vascular occlusion

Rodríguez

Miller

Boyle

et al. 2014

Journal of the Mechanical Behavior of Biomedical Materials

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Predominantly closed-cell low density shape memory polymer (SMP) foam was recently reported to be an effective aneurysm filling device in a porcine model (Rodriguez et al., Journal of Biomedical Materials Research Part A 2013: (http://dx.doi.org/10.1002/jbm.a.34782)). Because healing involves blood clotting and cell migration throughout the foam volume, a more open-cell structure may further enhance the healing response. This research sought to develop a non-destructive reticulation process for this SMP foam to disrupt the membranes between pore cells. Non-destructive mechanical reticulation was achieved using a gravity-driven floating nitinol pin array coupled with vibratory agitation of the foam and supplemental chemical etching. Reticulation resulted in a reduced elastic modulus and increased permeability, but did not impede shape memory behavior. Reticulated foams were capable of achieving rapid vascular occlusion in an in vivo porcine model.

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“…1 There has been generally a demand to automotive seating foams of lower transmissibility at resonance frequency and at 6 Hz to prevent the transmission of vibration for human body, and mechanism of riding comfort has been studied by means of the dynamic mechanical behavior of open-cell flexible foams containing compressible and incompressible fluids. [15][16][17] Table V shows the vibration characteristic of each foam. The foam's viscoelastic response may be modeled as the combination of a spring with spring constant (designated K) in…”

Section: Dynamic Propertymentioning

confidence: 99%

Automotive Seating Foams with Excellent Riding Comfort Prepared by a Novel Polypropylene Glycol

Wada

Toyota

Horie

et al. 2008

Polym J

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A novel polypropylene glycol (designated PPG) which contains an extremely smaller amount of by-products (monols) was developed to improve the riding comfort of an automotive seating foams. The current trend in the automotive seating industry is moving to low resilience molded foam due to the structure change from ''full foam'' to ''foam and high tension spring combination,'' new automotive seating foams were desired to have low resilience with keeping the low transmissibility at 6 Hz. Riding comfort mainly consists of three factors such as static property, dynamic property and durability. Each issue was solved by means of increasing the polymer molecular weight and the crosslinking density in the polymer matrix. Furthermore, it was also cleared that the transmissibility at resonance frequency of the foam can lower by means of the adjustment of closed cell ratio in the foam. In this paper, we describe the foam properties (static property, dynamic property, durability) of TDI/MDI based molded foams and make clear the mechanism of the Riding comfort of automotive seating foams.

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Viscoelastic Behavior of Open Cell Foams

Cited by 34 publications

References 0 publications

Validation of a Nonlinear Automotive Seat Cushion Vibration Model

Validation of a Nonlinear Automotive Seat Cushion Vibration Model

Reticulation of low density shape memory polymer foam with an in vivo demonstration of vascular occlusion

Automotive Seating Foams with Excellent Riding Comfort Prepared by a Novel Polypropylene Glycol

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