en سازه Body structure پژوهشي Research <span style="font-size:10.0pt"><span style="line-height:115%"><span new="" roman="" style="font-family:" times="">Thin-walled tubes can avoid the transition of injurious acceleration and excessive forces to the protected section and minimize the damage severity.</span></span></span> <span style="font-size:10.0pt"><span style="line-height:115%"><span new="" roman="" style="font-family:" times="">They absorb energy under axial loading circumstances as crashworthiness structures. The present study deals with the investigation of the density effects of foam on the quasi-static loading response of foam filled and empty cylindrical tubes.</span></span></span> <span style="font-size:10.0pt"><span style="line-height:115%"><span new="" roman="" style="font-family:" times="">To investigate energy absorption parameters by varying in foam density, two different densities of polyurethane foam were used to evaluate the efficacy of polyurethane foam density under axial quasi-static loading<b>. </b>According to the results, the use of foam as a filler also influences the tubes&rsquo; deformation behavior in addition to the effects of thickness. It was revealed that by incrementing the thickness to 20%, the peak load increased by 25.2%. Two densities of foam were considered as 40 and 85kg/m3 to assess the effect of density of polyurethane foam as filler on the energy absorption behavior of tubes under axial loading<span style="background-color:#ffffff;">. </span><span style="background:yellow"><span style="background-color:#ffffff;">Result showed that when foam density increased by about two times, the peak load increased by 1%.</span></span><span style="background-color:#ffffff;"> A</span>ccording to the results, filling tube by foam also influences the tubes deformation behavior in addition to the effects of thickness</span></span></span> Polyurethane foam, Foam filled cylindrical tubes, Foam density, Axial loading, Crashworthiness 4110 4118 http://ase.iust.ac.ir/browse.php?a_code=A-10-461-3&slc_lang=en&sid=1 Farid Raoof raoof.farid@yahoo.com 180031947532846004100 180031947532846004100 No Department of Mechanical Engineering, Lahijan Branch, Islamic Azad University, Lahijan, Iran Javad Rezapour javad.rs82@gmail.com 180031947532846004101 180031947532846004101 Yes Department of Mechanical Engineering, Lahijan Branch, Islamic Azad University, Lahijan, Iran Sina Gohari Rad sina.g.rad@gmail.com 180031947532846004102 180031947532846004102 No Department of Mechanical Engineering, Rasht Branch, Islamic Azad University, Rasht, Iran Reza Rajabiehfard r.rajabiehfard@gmail.com 180031947532846004103 180031947532846004103 No Department of Mechanical Engineering, Rasht Branch, Islamic Azad University, Rasht, Iran