Anal fistula is one of the three greatest anorectal diseases with a high prevalence.The traditional treatments(e.g.,surgery) for fistula have limitations due to damage to the internal anal sphincter of patients.With recent advances in biomaterials,treatments based on biomaterial filling (e.g.,scleraprotein injection,fistula plug) have emerged as novel therapies for fistula.The anal fistula plug(e.g.,based on small intestinal submucosa(SIS)) has attracted increasing attention because of short term healing rate and biocompatibility.However,challenges remain for this method such as plug falling as observed in clinics.To address this,this paper analyzes the case of SIS falling under physiological condition from mechanical point of view using ANSYS simulation.It then proposes three new geometrical structures for fistula plug and compares their mechanical behavior(e.g.,axial stress,reaction of constraint) with that of clinically used structure(cone shape).Based on the simulation,it optimizes the geometric parameters of fistula plug.The approach developed here can help to improve the design of fistula plug for better clinical treatments.
Shunli YangBin JiangFeng XuMin LinGuiping ZhaoTianjian Lu
The methods of homogenization and finite elements are employed to predict the effective elastic constants and stress-strain responses of a new type of lattice structure,the X-structure proposed by the authors in a companion paper. It is shown that in most cases the predictions by the equivalent homogenization theory agree well with the experimental and 3-dimensional finite element calculated results. The theoretical and numerical study supports the argument that the X-structure is superior to the pyramid lattice structure in terms of mechanical strength.
ZHANG QianCheng1,CHEN AiPing 2,CHEN ChangQing2,3 & LU TianJian2 1 State Key Laboratory for Mechanical Behavior of Materials,School of Material Science and Engineering,Xi’an Jiaotong University,Xi’an 710049,China
Different surface morphologies of polyimide(PI)foils widely applied in flexible electronics were obtained using the technique of sandblasting.Copper(Cu)films were subsequently deposited on the treated surface of PI substrates.Upon tensile loading, the critical strain,crack density and count of cracks were measured to examine the ductility of Cu films on PI substrates.Obtained results show that after sandblasting treatment,the critical strain of Cu film decreases from 8.0%to 6.9%and,in comparison with the case without sandblasting,its surface crack density decreases remarkably,with no saturation of the crack density.The reduced crack density is attributed to the increase of contact area and interfacial adhesion after sandblasting,and whether the crack density is saturated or not is dependent upon the morphology of the cracks formed as a function of tensile strain.
YANG JinShui,XU Wei,WANG Fei&LU TianJian MOE Key Laboratory for Strength and Vibration,Xi’an Jiaotong University,Xi’an 710049
Recent development of ultralightweight lattice-cored sandwiches is reviewed,with focus placed on various novel fabrication methods introduced to strengthen these structures,covering not only research results published in the Science China Series E-Tech Sci,but also those in other domestic and overseas scientific journals.
LU TianJian 1 &ZHANG QianCheng 2 1 MOE Key Laboratory for Strength and Vibration,School of Aerospace,Xi’an Jiaotong University,Xi’an 710049,China
Self-oscillating polymer gels driven by Belousov-Zhabotinsky (BZ) chemical reaction are a new class of functional gels that have a wide range of potential applications (e.g., autonomously functioning membranes, actuate artificial muscles). However, the precise control of these gels has been an issue due to limited investigations of the influences of key system parameters on the characteristics of BZ gels. To address this deficiency, we studied the self-oscillating behavior of BZ gels using the nonline-ar dynamics theory and an Oregonator-like model, with focus placed upon the influences of various system parameters. The analysis of the oscillation phase indicated that the dynamic response of BZ gels represents the classical limit cycle oscillation. We then investigated the characteristics of the limit cycle oscillation and quantified the influences of key parameters (i.e., ini-tial reactant concentration, oxidation and reduction rate of catalyst, and response coefficient) on the self-oscillating behavior of BZ gels. The results demonstrated that sustained limit cycle oscillation of BZ gels can be achieved only when these key pa-rameters meet certain requirements, and that the pattern, period and amplitude of the oscillation are significantly influenced by these parameters. The results obtained in this study could enable the controlled self-oscillation of BZ gels system. This has several potential applications such as controlled drug delivery, miniature peristaltic pumps and microactuators.
WANG PengFei1, ZHOU JinXiong1, LI MeiE2, XU Feng1,3 & LU TianJian1 1 Biomedical Engineering and Biomechanics Center, SV Laboratory, Xi’an Jiaotong University, Xi’an 710049, China
A new type of ultra-lightweight metallic lattice structure (named as the X-type structure) is reported. This periodic structure was formed by two groups of staggered struts in the traditional pyramid strurture, and fabricated by folding expanded metal sheet along rows of offset nodes and then brazing the folded structure (as the core) with top and bottom facesheets to form sandwich panels. The out-of-plane compressive and shear properties of the X-type lattice sandwich structure were investigated experimentally and compared to those of the sandwich having a pyramidal truss core. It is found that the formation of the 2-dimensional staggered nodes can effectively make the X-type structure more resistant to inelastic and plastic buckling under both compression and shear loading than the pyramidal lattice truss. Obtained results show that the compressive and shear peak strengths of the X-type lattice structure are about 30% higher than those of the pyramidal lattice truss having the same relative density.
The radiation of noise from a parallelly rib-stiffened skin plate of aircraft cabin fuselage in the presence of external mean flow is theoretically investigated.An aero-acoustic-elastic model is developed and used to calculate the radiated sound pressure level(SPL) versus frequency curves with reference to sound radiation of a bare plate immersed in a steady fluid.The flexural and rotational motions of the rib stiffeners are described by applying the Euler-Bernoulli beam theory and torsional wave equation,respectively.Therefore,the coupling forces and moments between the ribs and the face-panel,caused separately by flexural and rotational motion of the ribs,are both taken into account.Given the periodicity of the structure,the Fourier transform technique is employed to solve panel vibration equations and acoustic equations.Systematic parametric investigation demonstrates that the presence of mean flow as well as rib spacings play significant roles in the sound radiation behavior of parallelly rib-stiffened plates.The proposed model provides a convenient and efficient tool for the factual engineering design of this kind of periodic structures with acoustic requirements.
