Nonlinear Modelling, Design, and Test of Steel Blast-Resistant Doors

The nonlinear dynamic response for steel blast-resistant doors is here described, referring to an innovative experience at both national and international level requiring an ad hoc design and specific numerical simulations. The elements capability to sustain thermal loads due to fire hazards is additionally accounted for. The study has been conducted to define and characterize the nonlinear behaviour of a large number of doors, with the objective of sustaining dynamic loads from explosive hazards of fixed magnitude, as well as variable design and clearing times. The local overcome of the material strength limit (with correspondent plastic response) and possible formation of plastic hinges has been critically discussed. Numerical models have allowed for refining first design sketches and subsequently understanding the real thermomechanical behaviour for the investigated elements. Some experimental tests have been additionally performed, verifying the correctness of the already available numerical results, validating the adopted procedures, and correspondingly guaranteeing the doors' structural efficiency even under dynamic loads higher than design ones

Computer-guided bone lid osteotomy with piezosurgery.

Aim: The aim of this paper is to present a case of mandibular cyst in proximity to the left inferior alveolar nerve and the adjacent teeth successfully treated with computer-guided bone lid technique. Case presentation: A patient was referred to our Department with an asymptomatic radiolucent lesion in the left mandible coinciding with the edentulous site of a second premolar. The lesion was confirmed using cone-beam computed tomographic imaging. Two tooth-supported computeraided design/computer-aided manufacturing guided surgical templates were designed and produced to guide the piezoelectric tips on the planned osteotomy planes. The cystic lesion was accessed through a buccal bone lid fashioned using a piezoelectric device. The lesion was removed and the bone lid was returned to its original position and stabilized with fixation microplates. Conclusions: Alveolar bone lesions can be treated successfully with bone lid techniques using piezosurgery. Computer-guided bone surgery offers the advantages of accurate and conservative surgical planning, enabling a safer and easier procedure