INTEGRATED LOAD OPTIMIZATION OF ELASTIC‐PLASTIC AXISYMMETRIC PLATES AT SHAKEDOWN

An elastic‐plastic axisymmetric steel bending plate subjected to a repeated variable load (RVL) is considered. The solution to the load optimization problem at shakedown is complicated because the stress‐strain state of the dissipative systems (e.g. the plate plastic deforming) depends on their loading history. A new algorithm for the load optimization problem combining von Mises and Tresca yield criterion based on the Rosen project gradient method is proposed. The optimization results are obtained by integrating the existing software and that created by the authors. Santrauka Nagrinejama tampriai plastine simetrine lenkiama plokšte, veikiama kintamosios kartotines apkrovos. Prisitaikančiu konstrukciju itempiu ir deformaciju būvis priklauso nuo apkrovimo istorijos. Plokštes apkrovos optimizavimo uždavinio matematiniame modelyje naudojamos stiprumo ir standumo salygos. I apkrovimo istorija atsižvelgiama, pasitelkiant ekst‐remines iražu ir ilinkius ribojančias ju normines reikšmes. Remiantis Rozeno projektuojamuju gradientu metodu sukurtas naujas apkrovos optimizavimo algoritmas, derinantis Mizeso ir Treska takumo salygas. Skaitinio pavyzdžio rezultatai gauti originalia autoriu kompiuterine programa. Reikšminiai žodžiai: prisitaikymas, ekstreminiai energetiniai principai, tampriai plastine plokšte, Mizeso ir Treska takumo salygos, matematinis programavima

Injectable alginate hydrogel loaded with GDNF promotes functional recovery in a hemisection model of spinal cord injury

We hypothesized that local delivery of GDNF in spinal cord lesion via an injectable alginate hydrogel gelifying in situ would support spinal cord plasticity and functional recovery. The GDNF release from the hydrogel was slowed by GDNF encapsulation in microspheres compared to non-formulated GDNF (free GDNF). When injected in a rat spinal cord hemisection model, more neurofilaments were observed in the lesion when the rats were treated with free GDNF-loaded hydrogels. More growing neurites were detected in the tissues surrounding the lesion when the animals were treated with GDNF microsphere-loaded hydrogels. Intense GFAP (astrocytes), low III tubulin (neural cells) and RECA-1 (endothelial cells) stainings were observed for non-treated lesions while GDNF-treated spinal cords presented less GFAP staining and more endothelial and nerve fiber infiltration in the lesion site. The animals treated with free GDNF-loaded hydrogel presented superior functional recovery compared with the animals treated with the GDNF microsphere-loaded hydrogels and non-treated animals