Strain-rate effects on elastic and early cell-collapse responses of a polystyrene foam

Song, Bo; Chen, Weinong W.; Dou, Songbai; Winfree, Nancy A.; Kang, Joseph H.

doi:10.1016/j.ijimpeng.2004.02.003

Cited by 90 publications

(39 citation statements)

References 32 publications

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“…This sensitivity to strain-rate appears more pronounced at high strain rates in the region of 1,000 s-1, a region representative of impact conditions [16,17]. The high strainrate dependence of polymeric foams has been attributed to both the matrix material properties and the presence of air inside the foam [13].…”

Section: Viscoelastic Characteristic Dependenciesmentioning

confidence: 97%

Viscoelastic impact characterisation of solid sports balls used in the Irish sport of Hurling

2011

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In recent years, variability in behaviour of the sliotar, a small leather-bound ball used in the Irish sport of hurling, has become evident in championship matches. The inconsistency in performance was attributed to the range of constructions and material compositions of currently approved ball types. With a view to adopting a standard core, a new methodology has been commissioned to assess the dynamic impact behaviour of approved sliotar cores. In this paper, the relationship between the dynamic stiffness and the coefficient of restitution is presented with regard to material properties, ball construction and viscoelastic strain and strain-rate dependencies. The modern polymer ball types were shown to exhibit strain-rate sensitivity, while the performance of the traditional multi-compositional ball types exhibited lesser strain-rate dependence. The traditional balls types were shown to be up to 2.5 times stiffer than the modern ball types, with this finding having implications for ball energy dissipation.

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Section: Viscoelastic Characteristic Dependenciesmentioning

confidence: 97%

Viscoelastic impact characterisation of solid sports balls used in the Irish sport of Hurling

2011

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“…Therefore, there are many studies focused on constitutive relationships of polymer foams [3][4][5]. Compressive properties at dynamic strain rates are very important for shock absorbers; therefore, many researchers have studied energy absorption performance of polymer foams at dynamic strain rates by using Split Hopkinson Pressure Bar (SHPB) equipment [6,7]. In general, these foams are suitable enough to absorb impact energy at room temperature.…”

Section: Introductionmentioning

confidence: 99%

The compressive behaviour and constitutive equation of polyimide foam in wide strain rate and temperature

Yoshimoto

Kobayashi

Horikawa

et al. 2015

EPJ Web of Conferences

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Abstract. These days, polymer foams, such as polyurethane foam and polystyrene foam, are used in various situations as a thermal insulator or shock absorber. In general, however, their strength is insufficient in high temperature environments because of their low glass transition temperature. Polyimide is a polymer which has a higher glass transition temperature and high strength. Its mechanical properties do not vary greatly, even in low temperature environments. Therefore, polyimide foam is expected to be used in the aerospace industry. Thus, the constitutive equation of polyimide foam that can be applied across a wide range of strain rates and ambient temperature is very useful. In this study, a series of compression tests at various strain rates, from 10 −3 to 10 3 s −1 were carried out in order to examine the effect of strain rate on the compressive properties of polyimide foam. The flow stress of polyimide foam increased rapidly at dynamic strain rates. The effect of ambient temperature on the properties of polyimide foam was also investigated at temperature from −190• C to 270• C. The flow stress decreased with increasing temperature.

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“…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.…”

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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Strain-rate effects on elastic and early cell-collapse responses of a polystyrene foam

Cited by 90 publications

References 32 publications

Viscoelastic impact characterisation of solid sports balls used in the Irish sport of Hurling

Viscoelastic impact characterisation of solid sports balls used in the Irish sport of Hurling

The compressive behaviour and constitutive equation of polyimide foam in wide strain rate and temperature

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

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