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Circular saw blades are widely used in stone processing. The circular saw blade cutting hard rock numerical simulation model based on ANSYS/LS-DYNA was established to investigate the complex dynamic problem in rock cutting. The failure mechanism of the rock and the influence of cutting parameters on the cutting force and rock fragments were studied by numerical simulation. The results demonstrated that the failure modes of the rock were mainly tensile failure with some shear failure and compressive failure. The cutting force and the number of fragments increased with the feed speed. With the increasing circular saw blade rotational speed, the cutting force and the number of fragments decreased and tended to stabilize. With the distance between the circular saw blades increasing, the cutting force and rock fragments number increase and then maintain basic stability, and when the distance between double circular saw blades reaches 25 mm, it will form a completed rock plate and the interaction of circular saw blades will decrease. The numerical simulation can accurately simulate rock breakage and force when a circular saw blade cuts rock. [ABSTRACT FROM AUTHOR]

A simple and effective mechanical parts maintenance approach with lower cost is urgently needed by the cost-sensitive manufactures for traditional excavators (HE). This paper proposes maintenance strategy for hydraulic cylinders (HC) of HE with energy regeneration and recovery system (ERRS). Reliability analysis and FMEA of historical failure data are applied to make maintenance strategy. In this study, the failure data required for reliability analysis are collected from the manufacturers and users over two and a half years, Excel is used as statistical tool, Minitab is used for parameter estimation, and Kolmogorov–Smirnov test is used to reject or accept the hypothesis of the distribution model. The reliability parameters R(t), Rset, and R∗(t) are determined and parameter β∗ is the reference value for making countermeasures and maintenance policies properly for the failure modes of the new HC of HE with ERRS. The purpose of this paper is to make proper maintenance policies and to maintain a high availability level and fulfill the user's needs for HC, which also paves the way for further reliability study about ERRS. [ABSTRACT FROM AUTHOR]

It is important to allocate a reliability goal for the hydraulic excavator in the early design stage of the new system. There are some effective methods for setting reliability target and allocating its constituent subsystems in the field of aerospace, electric, vehicles, railways, or chemical system, but until now there is no effective method for the hydraulic excavator or engineering machinery. In this paper, an approach is proposed which combines with the conventional reliability allocation methods for setting reliability goals and allocating the subsystem and parts useful in the early design stage of the hydraulic excavator newly developed. It includes Weibull analysis method, modified Aeronautical Radio Inc. (ARINC) method, and modified systematic failure mode and effect analysis (FMEA) method. After completing reliability allocation, it is necessary to organize the designers and experts to evaluate the rationality of the reliability target through FEMA analysis considering feasibility of the improvement technically for the part which was new developed or had fault in its predecessor. The proposed approach provides an easy methodology for allocate a practical reliability goal for the hydraulic excavator capturing the real life behavior of the product. It proposes a simple and unique way to capture the improvement of the subsystems or components of the hydraulic excavator. The proposed approach could be extended to consider other construction machinery equipment and have practicality value to research excellent mechanical product. [ABSTRACT FROM AUTHOR]

The investigation on the effect of defects on the mechanical properties of composites is vital to explain the failure mechanism of materials. A computer tomography (CT) scanning in-situ shear test is designed to obtain u-CT images of plain weave glass-fiber reinforced composites. The images are then applied to reconstruct the samples by using image processing techniques. Damage evolution characterization of the plain weave glass-fiber composites under in-situ shear experiment are realized by visualizing damages in three dimension. The damage evolution process is compared with the numerical simulation results to verify the materials failure mode. [ABSTRACT FROM AUTHOR]

• Based on the idea of reverse modeling, a finite element modeling method for CT images is proposed. • NURBS is utilized to fit complex boundary of model, which can greatly improve the finite element computational efficiency while ensuring the accuracy of the model. • The mechanical properties and failure modes of interlocked structures were studied by experiments and simulations. • The failure mode of structure is related to arrangement of pores, which can be improved by adjusting the printing strategy. Suture-inspired interlocked interfaces in nature exhibit promising industrial application potentials for advanced mechanical structures, devices and equipment. It is of significant scientific interest for studying the pull-out response and failure mode of interlocked structure as well as internal stress variations during the loading process. In this paper, finite element analysis (FEA) simulation based on X-Ray tomographic images is proposed for understanding the effects of manufacturing defects on the performances of interlocked structures, which are of critical importance for controlling the stress evolution of the interface structure and corresponding failure modes. Firstly, X-ray micro computed tomography (micro-CT) was applied for non-destructive scanning inspection of aluminum alloy additive manufacturing samples, high spatial resolution and calculation efficiency can be realized through tomographic image guided FEA scheme for generating high fidelity simulation results. Afterwards, non-uniform rational B-splines fitting method was employed for optimizing sample boundaries harvested from CT images, which allows smooth conversion from CT pixel images to high precision fitted finite element model. The B-spine fitting model can significantly improve the computational efficiency for finite element simulation without losing calculation reliability and resolution, overcoming the inherent contradictions between efficiency and resolution of the traditional pixel image finite element method. Finally, considering the mechanical contributions and interactions of external and internal porosity defects, the failure modes of the interlocked structures were further analyzed based on the results of finite element analysis. [ABSTRACT FROM AUTHOR]