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.

Development of flexible telescopic boom model using ANCF sliding joint constraints with LuGre friction

In this investigation, a modeling procedure of a telescopic boom of cranes is developed using the absolute nodal coordinate formulation together with the sliding joint constraints. Since telescopic booms are extracted and retracted under various operating conditions, the overall length of the boom changes dynamically, leading to the time-variant vibration characteristics. For modeling the telescopic structure of booms, a special care needs to be exercised since the location of the sliding contact point moves Mong the deformable axis of the flexible boom and the solution to a moving boundary problem is required. This issue indeed makes the modeling of the telescopic boom difficult, despite the significant needs for the analysis. It is, therefore, the objective of this investigation to develop a modeling procedure for the flexible telescopic boom by considering the sliding contact condition with the dynamic frictional effect. To this end, the sliding joint constraint developed for the absolute nodal coordinate formulation is employed for describing relative sliding motion between flexible booms, while flexible booms are modeled using the beam element of the absolute nodal coordinate formulation, which allows for modeling the large rotation and deformation of the structure.

A novel stiffness optimization model of space telescopic boom based on locking mechanism

The deployable telescopic boom,whose mass and stiffness play crucial roles,is extensively used in the design of space-deployable structures.However,the most existing optimal design that neglects the influence of the locking mechanisms in boom joints cannot raise the whole stiffness while reducing the boom mass.To tackle this challenge,a novel optimization model,which utilizes the arrangement of the locking mechanisms to achieve synchronous improvement of the stiffness and mass,is proposed.The proposed optimization model incorporates a novel joint stiffness model developed based on an equivalent parallel mechanism that enables the consideration of multiple internal stiffness factors of the locking mechanisms and tubes,resulting in more accurate representations of the joint stiffness behavior.Comparative analysis shows that the proposed stiffness model achieves more than at least 11% improved accuracy compared with existing models.Furthermore,case verification shows that the proposed optimization model can improve stiffness while effectively reducing mass,and it is applied in boom optimization design.

M-LFM:a multi-level fusion modeling method for shape−performance integrated digital twin of complex structure

As a virtual representation of a specific physical asset,the digital twin has great potential for realizing the life cycle maintenance management of a dynamic system.Nevertheless,the dynamic stress concentration is generated since the state of the dynamic system changes over time.This generation of dynamic stress concentration has hindered the exploitation of the digital twin to reflect the dynamic behaviors of systems in practical engineering applications.In this context,this paper is interested in achieving real-time performance prediction of dynamic systems by developing a new digital twin framework that includes simulation data,measuring data,multi-level fusion modeling(M-LFM),visualization techniques,and fatigue analysis.To leverage its capacity,the M-LFM method combines the advantages of different surrogate models and integrates simulation and measured data,which can improve the prediction accuracy of dynamic stress concentration.A telescopic boom crane is used as an example to verify the proposed framework for stress prediction and fatigue analysis of the complex dynamic system.The results show that the M-LFM method has better performance in the computational efficiency and calculation accuracy of the stress prediction compared with the polynomial response surface method and the kriging method.In other words,the proposed framework can leverage the advantages of digital twins in a dynamic system:damage monitoring,safety assessment,and other aspects and then promote the development of digital twins in industrial fields.