Abstract. The micro stick-slip motion systems, such as piezoelectric stick-slip actuators (PE-SSAs), can provide high resolution motions yet with a long motion range. In these systems, friction force plays an active role. Although numerous friction models have been developed for the control of micro motion systems, behaviors of these models in micro stick-slip motion systems are not well understood. This study (1) gives a survey of the basic friction models and (2) tests and compares 5 friction models in the literature, including Coulomb friction model, Stribeck friction model, Dahl model, LuGre model, and the elastoplastic friction model on the same testbed (i.e. the PE-SSA system). The experiments and simulations were done and the reasons for the difference in the performance of these models were investigated. The study concluded that for the micro stick-slip motion system, (1) Stribeck model, Dahl model and LuGre model all work, but LuGre model has the best accuracy and (2) Coulomb friction model and the elastoplastic model does not work. The study provides contributions to motion control systems with friction, especially for micro stick-slip or step motion systems as well as general micro-motion systems.
Polyetherketoneketone (PEKK) exhibits admirable biocompatibility and mechanical performances but bioinert while tantalum (Ta) possesses excellent osteogenesis and osseointegration but high elastic modulus and density, and processing is too difficult and expensive. In the present study, combining of the advantages of both PEKK and Ta, implantable composites of PEKK/Ta were fabricated by blending PEKK with Ta microparticles of 20 v% (PT20) and 40 v% (PT40) content. In comparison with PT20 and PEKK, the surface hydrophilicity, surface energy, roughness and proteins adsorption as well as mechanical performances of PT40 significantly increased because of the higher Ta particles content in PEKK. Furthermore, PT40 exhibited the mechanical performances (e.g., compressive strength and modulus of elasticity) close to the cortical bone of human. Compared with PT20 and PEKK, PT40 with higher Ta content remarkably enhanced the responses (including adhesion, proliferation and osteogenic differentiation) of MC3T3-E1 cells
in vitro
. Moreover, PT40 markedly improved bone formation as well as osseointegration
in vivo
. In short, incorporation of Ta microparticles into PEKK created implantable composites with improved surface performances, which played key roles in stimulating cell responses/bone formation as well as promoting osseointegration. PT40 might have great potential for bear-loading bone substitute.
Abstract. This paper provides a comprehensive review of the literature regarding the modeling and control of piezoelectric inertia-friction actuators (PIFAs). Examples of PIFAs are impact drive mechanisms (IDMs) and friction-driving actuators (FDAs). In this paper, the critical challenges are first identified in modeling and control of PIFAs. Second, a general architecture of PIFAs is proposed to facilitate the analysis and classification of the literature regarding modeling and control of PIFAs. This general architecture covers all types of PIFAs (e.g., FDAs, IDMs) and thus serves as a general conceptual model of PIFAs. There is an additional benefit with this general architecture of PIFAs, namely that it is conducive to innovation in PIFAs, as new specific PIFAs may be designed in order to tailor to a specific application (for example, both FDAs and IDMs are viewed as specific PIFAs). Finally, the paper presents future directions in modeling and control for further improvement of the performance of PIFAs.
Nanoporous tantalum pentoxide (NTP) particles with pore size of around 10 nm were synthesized and blended with polyetheretherketone (PEEK) to fabricate PEEK/NTP composite (PN). Subsequently, PN was treated by concentrated...
Pinus koraiensis polysaccharides (PKP) were extracted by hot water from P. koraiensis pine cones. Five polysaccharide fractions named PKP-A, PKP-B, PKP-C, PKP-D and PKP-E were successfully separated at final ethanol concentrations of 30%, 50%, 60%, 70% and 80%, respectively. HPLC, FT-IR, GC-MS and automatic amino-acid analysis were applied to investigate their chemical characteristics. , respectively. These results demonstrated that the PKP could be a potential source of natural antioxidants or dietary supplements.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.