Development of Foam Models as Applications to Vehicle Interior

Chou, Clifford C.; Zhao, Y.; Chai, Li; Co, J; Lim, G. G.; Lin, Tzung-Hsien

doi:10.4271/952733

Cited by 13 publications

(3 citation statements)

References 1 publication

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“…For this reason, the dependencies of the mechanical characteristics on the sample thickness and density, as well as on the processing method, are discussed. Avalle [4] refers to many experimental studies carried out to determine the compressive properties of steam-based EPP particle foam parts for automotive use [5][6][7][8][9][10][11][12][13][14][15]. It was pointed out that the results are rather inconsistent and not general enough.…”

Section: Theoriesmentioning

confidence: 99%

Comparison of Mechanical Properties of Steam-Free and Steam-Based Specimens Made of Expanded Polypropylene Beads

Handtke,

Hain,

Fischer

et al. 2024

Polymers

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Reducing the CO2 emissions of plastic parts is crucial in terms of sustainable product and process designs. Approaches include the use of recycled materials and reducing the energy demands of processes through more efficient technologies. In this context, this study shows the potential of the steam-free processing of particle foam beads into thin-walled moulded parts. Expanded polypropylene (EPP) particle foam beads have been processed in both a steam-free and steam-based process. For this purpose, specimens with different part densities and thicknesses were produced, the mechanical properties were investigated, and the surface quality was discussed. Specimens made of EPP with a part thickness of 5 to 20 mm and part densities of 60 to 185 g/L were produced steam-free. Lower part thicknesses and higher densities increase the mechanical properties. As the density increased, the homogeneity of the surfaces of the steam-free specimens also increased. In comparison, specimens with a thickness of 10 mm and part densities of 35 to 90 g/L were produced on a steam-based process. The results of the mechanical test were compared with those of the steam-free specimens. The steam-based specimens showed higher mechanical properties for the same density.

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Section: Theoriesmentioning

confidence: 99%

Comparison of Mechanical Properties of Steam-Free and Steam-Based Specimens Made of Expanded Polypropylene Beads

Handtke,

Hain,

Fischer

et al. 2024

Polymers

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“…They fitted the compression test data of single-layer polyurethane foam using the strain energy equation of the hyperfoam (Ogden) model. Chou et al (1995) investigated the stress-strain relations of single-layer foam with various foam models of LS-DYNA 3D; numerous simulations were carried out for foams subjected to different loading conditions. By combining the advanced measurement techniques, nontraditional experimental setup, numerical modeling (FE model) and inverse analysis one can capture all nine elastic properties of single-layer polymer foam from just two or three tests (Chuda-Kowalska et al 2015).…”

Section: Introductionmentioning

confidence: 99%

Finite element analysis of compressive stress-strain relations in elastic materials for seat foundation

Li,

Yu,

et al. 2023

BioRes

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Elastic materials for seat foundations come in a variety of materials, shapes, and dimensions. However, it is difficult to measure the stress-strain relationships of many elastic material combinations by conventional uniaxial compression tests. This study investigated the stress-strain relations of elastic material combinations for foam foundations using finite element analysis (FEA). First, the stress-strain relations of single-layer polymer foams and a combination of double-layer polymer foams with covering were quantified by uniaxial compression tests, and axial tensile tests quantified the properties of the covering material of the fabric. Then, based on the Ogden foam and Ogden constitutive equation of Ansys Workbench 19.2, the test data of single-layer polymer foams and covering were fitted by a non-linear least square method, and a combination of double-layer polymer foams with the covering is predicted by FEA. When the strain was 10% to 65%, the stress error between FEA and test results dropped from 95.68% to -5.08%.

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“…As mentioned earlier and revealed through the survey of a cross-section of relevant literature ( [14], [15], [16], [17], [18], [19], [20], [21]), methods exist for the determination of stressstrain responses of foam at medium to high strain rates. However, the method discussed here according to which UTM-based tests at low strain rates are supplemented with drop-weight impact tests and a scaling technique has not been reported earlier.…”

Section: Introductionmentioning

confidence: 99%

A Methodology for Characterization of the Strain Rate-Dependent Behavior of PU Foam

Shivakumar¹,

Deb²,

Chou³

et al. 2014

SAE Int. J. Mater. Manf.

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Dynamic characterization of foam i.e. finding stress-strain responses at strain rates higher than quasi-static is essential for predicting its behavior in many real-world applications such as energy-absorption under impact loads. However, generating stress-strain data at dynamic strain rates is often a challenging task due to the necessity of specialized equipment such as a Split Hopkinson Pressure Bar [1, 2, 3] which can be expensive and not ordinarily available in an engineering laboratory. This device, despite perhaps being the best resource for ascertaining material behavior at high strain rates, has limitations due to its indirect nature arising from reliance on one-dimensional wave theory for solids, difficulty in performing tensile tests, special material requirements for incident and transmission bars for testing of soft materials such as foam and fibre-reinforced composites, etc. Additionally, the SHPB is generally suitable for strain rates of the order of 1000 s −1 or higher [4] although SHPB tests on polymeric foams with acrylic bars have been reported for strain rates in the range of 500-2500 s −1 [5].Due to the relevance of rigid PU foam for impact safety and packaging applications, attention is paid here toward developing a simple methodology for determining the stressstrain responses of a rigid PU foam at low to medium strain rates. However, it may be pointed out that the methodology adopted is not dependent on the type of foam being considered and can be applied to cellular materials in general. ABSTRACTPolymeric foams are known to be sensitive to strain rate under dynamic loads. Mechanical characterization of such materials would not thus be complete without capturing the effect of strain rate on their stress-strain behaviors. Consistent data on the dynamic behavior of foam is also necessary for designing energy-absorbing countermeasures based on foam such as for vehicle occupant safety protection. Strain rates of the order of 100-500 s −1 are quite common in such design applications; strain rates of this range cannot be obtained with an ordinary UTM (universal testing machine) and a special test set-up is usually needed. In the current study, a unique approach has been suggested according to which quasi-static tests at low strain rates and low velocity drop tests at medium strain rates are utilized to arrive at an empirical relation between initial peak stress and logarithm of strain rate for a rigid closed-cell PU foam. Using a stress-scaling methodology and the empirical relation mentioned, foam stress-strain curves are obtained for a number of strain rates spanning low (from 0.00033 s −1 ) to high strain rates (up to1000 s −1 ). This data on foam material behavior is expected to be particularly useful in numerical modelling of foam-based countermeasures for impact energy absorption applications.

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Development of Foam Models as Applications to Vehicle Interior

Cited by 13 publications

References 1 publication

Comparison of Mechanical Properties of Steam-Free and Steam-Based Specimens Made of Expanded Polypropylene Beads

Comparison of Mechanical Properties of Steam-Free and Steam-Based Specimens Made of Expanded Polypropylene Beads

Finite element analysis of compressive stress-strain relations in elastic materials for seat foundation

A Methodology for Characterization of the Strain Rate-Dependent Behavior of PU Foam

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