Dynamic Crush Tests Using a "Free-Flight" Drop Tower: Practical Aspects

Johnson, Nancy L.; Browne, Alan L.

doi:10.1111/j.1747-1567.2002.tb00091.x

Cited by 4 publications

(10 citation statements)

References 4 publications

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“…Table 1 shows the energy absorbed for different carbon steel tubes covered with stainless steel pipe specimens. While certain energy is lost (5–16%) in drag and friction, 1,2 the remaining energy is converted into deformation energy. Currently, rigid polyurethane foam (PUF) specimens are being investigated for their energy absorption capacity for application in nuclear transportation packages.…”

Section: Energy Absorbersmentioning

confidence: 99%

“…The study of impact response of structural components using drop experiments is of interest for design engineers of diverse fields because it provides vital inputs for (1) crashworthiness; (2) transportation of nuclear shipping casks; and (3) handling and in‐service shock assessment of engineering systems. For crashworthiness tests, free‐flight drop towers are used with drop platform and guide tubes 1,2 . Impact tests are performed by vertically raising the platform and then releasing it to fall freely under the action of gravity.…”

mentioning

confidence: 99%

“…For crashworthiness tests, free-flight drop towers are used with drop platform and guide tubes. 1,2 Impact tests are performed by vertically raising the platform and then releasing it to fall freely under the action of gravity. The kinetic energy of the drop platform is dissipated through the deformation of the specimen.…”

mentioning

confidence: 99%

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Impact Studies on Structural Components Using a Free-Flight Drop Tower

Bhattacharya¹,

Krishnamurthy²,

Rajendran³

et al. 2006

Experimental Techniques

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Section: Energy Absorbersmentioning

confidence: 99%

mentioning

confidence: 99%

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Impact Studies on Structural Components Using a Free-Flight Drop Tower

Bhattacharya¹,

Krishnamurthy²,

Rajendran³

et al. 2006

Experimental Techniques

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“…A high-speed digital video camera was used to record the motion of the MREA at high speed. More detailed descriptions of the high-speed drop tower facility are given in Browne and Johnson, (2001) and Johnson and Browne (2001).…”

Section: High-speed Drop Tower Testmentioning

confidence: 99%

Experimental validation of a magnetorheological energy absorber design analysis

Mao

Choi

et al. 2013

Journal of Intelligent Material Systems and Structures

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A key challenge when designing linear stroke magnetorheological energy absorbers for high-speed impact is that high piston speeds in linear stroke magnetorheological energy absorbers induce high Reynolds number flows in the magnetic valve of the magnetorheological energy absorber, so that achieving high controllable dynamic range can be a design challenge. So far, the research on magnetorheological energy absorbers has typically assumed that the off-state force increases linearly with piston velocity. But at the higher piston velocities occurring in impact events, the off-state damping exhibits nonlinear velocity squared damping effects. This problem was recognized in our prior work, where it was shown that minor losses are important contributing factors to off-state damping. In this study, a nonlinear analytical magnetorheological energy absorber model is developed based on a Bingham-plastic nonlinear flow model combined with velocity squared dependent minor loss factors. This refined model is denoted as the Bingham-plastic nonlinear flow model with minor losses. From this Bingham-plastic nonlinear flow model with minor losses, an effective design strategy is presented for conventional magnetorheological energy absorbers. The Bingham-plastic nonlinear flow model with minor losses is validated via computational fluid dynamics simulation, so that magnetorheological energy absorber performance can be analytically verified before being manufactured. The magnetorheological energy absorber is fabricated and tested up to an effective piston velocity of 5 m/s by using the high-speed drop tower facility at the GM R&D Center. Comparison of our analysis with measured data is conducted, and the effective design of the magnetorheological energy absorber using the Bingham-plastic nonlinear flow model with minor losses is validated.

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“…The sampling interval was 50 ms. A high speed digital video record was made of each impact test and Figure 7 contains time-spaced frames taken from the video of a representative MR damper impact test conducted on the low mass drop tower. More complete descriptions of the theory behind and the practical aspects of impact testing using a free-flight drop tower facility are given in Browne and Johnson (2001) and Johnson and Browne (2001), respectively.…”

Section: Test Proceduresmentioning

confidence: 99%

Impact Performance of Magnetorheological Fluids

Browne

McCleary

Namuduri

et al. 2008

Journal of Intelligent Material Systems and Structures

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As part of an emerging effort in what is now termed the area of mechamatronics (Browne et al., 2004), an effort was begun to assess the suitability of magnetorheological (MR) material-based devices for impact energy management applications. A fundamental property of MR materials is that their yield stress alters almost instantaneously (and proportionally) to changes in the strength of an applied magnetic field. Based on this property, MR-based devices, if found suitable, would be desirable for impact energy management applications because of attendant response tailorability. However, it was identified that prior to adopting MR-based devices for impact energy management applications several key issues needed to be addressed. The present study focuses on one of the most significant of these, the verification of the tunability of the response of such devices at stroking velocities representative of vehicular crashes. Impact tests using a free-flight drop tower facility were conducted on an MR-based energy absorber (shock absorber) for a range of impact velocities and magnetic field strengths. Results demonstrated that over the range of impact velocities tested — 1.0—10 m/s — the stroking force/energy absorption exhibited by the device remained dependent on, and thus could be modified by, changes in the strength of the applied magnetic field.

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Dynamic Crush Tests Using a "Free-Flight" Drop Tower: Practical Aspects

Cited by 4 publications

References 4 publications

Impact Studies on Structural Components Using a Free-Flight Drop Tower

Impact Studies on Structural Components Using a Free-Flight Drop Tower

Experimental validation of a magnetorheological energy absorber design analysis

Impact Performance of Magnetorheological Fluids

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