Simple hand calculation method for estimating deflection generated by the low velocity impact of a solid object

Ali, Muneeb; Sun, J; Lam, Nelson; Zhang, Lihai; Gad, Emad

doi:10.7158/s13-006.2014.15.3

Cited by 19 publications

(6 citation statements)

References 14 publications

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“…This may represent quite well the impact of a pressurised sport ball on a hard ground such concrete or wooden floor that may be encountered in basketball or handball. Differently, for outdoor sports such as football or rugby, the field is soft enough to be deformed elastically or plastically by the ball during the impact, changing the properties of impact [28,29]. This remark stands also for impact of pressurized balls or pressurised protections on humans which soft tissues (skin, muscles, etc.)…”

Section: Discussionmentioning

confidence: 99%

Impact of a pressurised membrane: Contact time

Tadrist

Texier

Lanzetta

et al. 2021

International Journal of Impact Engineering

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Pressurised membranes are used in various situations involving humans (protections, sports, etc).In this context, impacts mechanics of membranes is critical since under or over inflated membranes may create injuries. The effect of inflation pressure on contact time is investigated on a model experiment using a spherical membrane. Both gas pressure and impact speed decrease contact time. Direct measurements of gas pressure and temperature variations indicate an adiabatic compression in strong interaction with the membrane. The contact time of an inflated membrane is described by three dimensionless numbers, (i) the relative inflationP, (ii) the presso-elactic number P E that considers the gas-membrane interaction and (iii) the presso-inertial number I P that scales membrane inertia to pressure forces. A model of pressurised membrane impact is provided and compared with experiments. It shows that contact time depends mainly on I P with corrections on P E andP.

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Section: Discussionmentioning

confidence: 99%

Impact of a pressurised membrane: Contact time

Tadrist

Texier

Lanzetta

et al. 2021

International Journal of Impact Engineering

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“…The model was derived by the authors based on fundamental principles of energy and momentum. Analytical expressions for predicting the displacement demand of the impact have until now only been verified by impact on miniature models made of steel or wooden materials (refer Ali et al (2014), Lam and Gad (2016), Lam et al (2018b), Yang et al (2012)). For the design of a RC barrier walls, which are expected to respond within the elastic limit, the model takes the form of Equation (2).…”

Section: Displacement-based Analytical Modelmentioning

confidence: 99%

“…Parameter defines the ratio of the generalised mass of the target ( ) to the mass of the impactor ( ). The value of may be taken as a quarter of the mass of the stem wall based on established structural dynamics principles (Ali et al 2014, Sun et al 2016. This was derived based on the shape profile of a cantilevered wall, and will remain unaffected by crack formation as long as the limit of yield has not been surpassed.…”

Section: Displacement-based Analytical Modelmentioning

confidence: 99%

“…The proposed model has previously been validated using small-scale experimental testing, which involved dropping a small impactor object onto a mild steel bar or a wooden joist (e.g. Ali et al (2014), Lam and Gad (2016), Lam et al (2018b), Yang et al (2012)). This paper will present an experimental validation of the proposed DB model using a large-scale RC wall test specimen.…”

Section: Introductionmentioning

confidence: 99%

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Experimental and Analytical Assessment of Flexural Behavior of Cantilevered RC Walls Subjected to Impact Actions

et al. 2020

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Reinforced concrete (RC) impact-resistance barriers, such as rockfall barriers, often consist of a cantilever RC wall, which is expected to experience flexural bending under impact loading to resist the associated design actions. In order to investigate the flexural response behaviour of an RC cantilever wall, a large-scale experiment was carried out on a fixed base RC cantilevered barrier wall measured 1.5 m in height, 3 m in length and 0.23 m in thickness. Two "torpedo" shaped steel impactors with mass of 280 kg and 435 kg were released from controlled heights ranging from 0.2 m to 1.4 m in pendulum style to strike the top of the wall. The first half of this paper presents an overview, findings and results of this large-scale, original experimental work. The second half of the paper presents a displacement-based analytical model, which can be used to assess and determine important design parameters for cantilever RC barrier walls of this nature; including, deflection demand and material strains. Systematic comparisons of the experimental results and the proposed analytical model demonstrate the accuracy and reliability of the proposed model for assessing cantilevered RC barrier walls subject to impact actions.

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“…Recent research has shown that, although the contact force may cause localised damage, only a small fraction of the force is actually transmitted to the rest of the structure due to its inertial resistance (Ali et al 2014;Sun et al 2014). Therefore, the contact force generated by an impact could be an order of magnitude higher than the reaction force that the foundation need be designed to resist.…”

Section: Introductionmentioning

confidence: 99%

Overturning stability of L-shaped rigid barriers subjected to rockfall impacts

Lam¹,

Yong

Kwan³

et al. 2018

Landslides

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Reinforced concrete barriers are commonly used as defence measures in hilly areas to contain falling boulders and landslide debris. These barriers are conventionally designed to satisfy the conditions of force and momentum equilibrium with a factor of safety. A major limitation of this approach is that the inertial resistance of the barrier is neglected such that the design could be over-conservative. This paper presents a novel displacement-based approach for the assessment of overturning stability of rigid L-shaped barriers subjected to rockfall impacts. Analytical solutions, which are derived based on conservation of momentum and energy, are used to take into account the contributions of the self-weight and thus the inertial resistance of the barrier in resisting an impact. The actual amount of energy transferred from the impacting boulder to the barrier is considered by including the coefficient of restitution between the two objects. The accuracy of the analytical solutions has been confirmed by laboratory impact experiments.Numerical assessments conducted using the new solutions indicate that a reasonably sized rigid barrier, due to its own inertial resistance, may adequately withstand the impact action of a heavy boulder rolling down a hillslope without relying on any anchorage to its support. A range of geometric design of the barriers with L-shaped cross sections also have been considered and analysed. The new approach presented in this paper is easy to apply in practice and will be useful for engineers designing concrete barriers as passive rockfall mitigation measures.

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Simple hand calculation method for estimating deflection generated by the low velocity impact of a solid object

Cited by 19 publications

References 14 publications

Impact of a pressurised membrane: Contact time

Impact of a pressurised membrane: Contact time

Experimental and Analytical Assessment of Flexural Behavior of Cantilevered RC Walls Subjected to Impact Actions

Overturning stability of L-shaped rigid barriers subjected to rockfall impacts

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