Influence of Section Size of Telescopic Boom on Stability

The telescopic boom is the main bearing force component of the crane.The rationality of the design will directly affect the performance of the machine and safety.The telescopic boom is a typical thin-walled plate and shell structure.Its main form of damage is the occurrence of buckling,resulting in decreased carrying capacity,or even a security incident.In order to meet the lifting weight and height,to ensure the stability of the telescopic boom has become a major problem of the designer.There are many factors that affect the critical load of the telescopic boom,including support method,inertia moment,length and material.When the support mode,material and length are determined,the maximum factor affecting the buckling critical load is the inertia moment.In this paper,the influence of the section size on the buckling critical load of the telescopic boom is analyzed by using the inertia moment of section method ande finite element method.And the sensitivity analysis is carried out on this basis.The results of the analysis can provide designers with design reference basis.Then a reasonable cross-sectional size can be used to improve the buckling resistance capacity of the telescopic boom.

Dynamic behavior of single-layer latticed cylindrical shells subjected to seismic loading

The single-layer latticed cylindrical shell is one of the most widely adopted space-fl'amed structures.In this paper,free vibration properties and dynamic response to horizontal and vertical seismic waves of single-layer latticed cylindrical shells are analyzed by the finite element method using ANSYS software.In the numerical study,where hundreds of cases were analyzed,the parameters considered included rise-span ratio,length-span ratio,surface load and member section size.Moreover,to better define the actual behavior of single-layer latticed shells,the study is focused on the dynamic stress response to both axial forces and bending moments.Based on the numerical results,the effects of the parameters considered on the stresses are discussed and a modified seismic force coefficient method is suggested.In addition,some advice based on these research results is presented to help in the future design of such structures.

Application of the Largest Movable Mold EMS on a Large Section Size CC Bloom

The largest movable mold EMS developed by POSCO in collaboration with Daineli-Rotelec for improving internal quality of a large CC bloom is being used at a large size bloom caster of POSCO since 2011.Internal quality of carbon steel CC bloom of 700×700 mm~2 section size with the mold EMS was much improved compared with without the mold EMS.Equiaxed zone ratio increased from 50%to 100%and the grain of equiaxed structure became globular and fine.Top shrinkage was also much reduced by applying the movable mold EMS.