基于Creo/parametric,HyperMesh的装船机臂架有限元建模

装船机用于装船作业的连续式机械。它与后方皮带机系统相衔接,是一种高效率的港口装械作业机械。装船机高频率、高负荷的作业状态,复杂的工况,超大的自重载荷,使得装船机各种性能尤其是动态性能在很大程度上决定了装船机的安全、稳定运行的主导因素。

基于Creo Parametric的包装机曲柄滑块机构的优化设计

在Creo Parametric中,通过骨架模型,创建了偏置曲柄滑块机构模型,并对曲柄滑块机构进行了运动分析,应用Creo Parametric的行为建模功能,将滑块行程、最小压力角作为约束,对曲柄与连杆的长度进行了优化设计。该方法简单、实用性强,具有很大的推广价值,为曲柄滑块机构的设计提供了新的思路。

基于Creo Parametric的新型防堵装置运动仿真

结合被动式防堵装置和动力驱动式防堵装置的优缺点,开发了一种新型的滑板压秆旋切式防堵装置,并分析了该防堵装置的结构和工作原理。同时,采用Creo Parametric软件建立了三维几何模型,并通过Creo Parametric软件的机构模块对关键部件进行了干涉和运动仿真分析。通过分析确保该装置各部件之间不存在干涉,并得到其关键部件旋切平面刀端点的速度、速度X方向分量、速度Y方向分量及加速度、加速度X方向分量和加速度Y方向分量随时间的变化规律,旨在为滑板压秆旋切式防堵装置的结构优化提供科学依据。

基于Creo Parametric软件平台的混合式建模方法研究

计算机辅助工业设计在设计流程中的应用越来越广泛。通过对参数化建模和自由式建模的对比研究,指出了这两种方法各自的弊端,提出基于Creo Parametric软件平台的混合式建模办法。以电吹风产品模型构建的案例来说明混合式建模方法的工作流程,并通过模型分析验证了这种方法的可行性。

基于Creo Parametric的易拉罐外形尺寸的优化设计

结合实例应用Creo Parametric的行为建模功能,对易拉罐的外形尺寸进行了优化设计。在Creo Paramet-ric中以易拉罐外形尺寸为设计变量,以易拉罐容积为约束条件,以易拉罐金属用量最小为设计目标,进行了优化设计。该方法操作简便、优化结果可靠、推广性强。为易拉罐及其他包装容器的优化设计提供了新的思路。

基于Creo Parametric的风机叶片建模方法研究

由于风机叶片在三维软件中直接建模的复杂度,探讨了一种较快捷创建风机叶片的建模方法。利用NACA软件生成叶片翼型截面离散点坐标,并将结果导入Creo Parametric软件。通过混合等命令,将多段翼型截面曲线生成光滑的叶片曲面模型,并对生成的实体表面进行了曲面分析与检查。最后利用Flow Simulation等软件,对叶片进行了流体仿真及模态分析,得出了叶片压力最大值在叶片的设计承受范围内,且叶片一阶固有频率远大于风机转动时的频率,叶片发生共振的可能性很小的结论,很好的证明了叶片建模方法的可行性和实用性。通过这种建模方法,将很大程度减少叶片在设计时的工作强度与难度,提高设计人员的设计效率。

利用Creo Parametric的机构分析对装配中的碰撞关系进行精确求解

利用Creo Parametric软件的机构功能,通过"碰撞检测设置"选项,对元件运动过程中发生的碰撞作出警告提示。建立机构分析,设置合理的运动参数,并对运动进行动画回放,找到元件碰撞接触时的准确位置。

基于Creo Parametric技术的马尾松微观模型构建

【目的】为实现木材微观构造的宏观化,更直观全透认识木材生物结构,将其细胞组织从二维平面图像转到三维立体图像,基于参数化设计模块Creo Parametric建模技术,构建出马尾松Pinus massoniana微观构造的立体模型。【方法】首先通过光学显微镜观察马尾松三切面的微观构造图像,然后对构成马尾松木材各类组织的细胞类型、组织比量和形态尺寸进行观测定量化分析;基于观察与分析结果,对马尾松典型细胞的结构形貌及胞壁上结构特征进行三维模型构建,将构建的模型导入弘瑞3D打印系统(modellight)进行模拟分析与模型打印。【结果】针叶材马尾松解剖分子排列规则,管胞约占木材体积90%,其他细胞为木射线、轴向薄壁组织和树脂道等。基于各类细胞的真实形态特征构建单个细胞模型,在单个细胞的3D模型基础上根据各类组织分布与排列规律将各细胞进行组装,获得针叶材马尾松木材微观构造的立体模型。运用3D打印技术将虚拟的模型实体化,构造出等比例放大200倍的微观实物模型。【结论】本研究证实3D技术在木材微观构造水平建模的可行性,将丰富的木材微观结构以实体化的形式展现,为充分了解木材内部特征提供便利,也为木材学教学和木材美学价值开发提供参考,为植物遗态生物质高性能仿生材料研究提供生物学理论基础。

基于Creo Parametric“轨迹曲线”的袋成型包装机热封凸轮廓线设计

通过对热封机构工作原理的分析,将凸轮坯作为"纸零件",摆杆滚子中心点作为参考,基于Creo Parametric机构模块的"轨迹曲线"功能,绘制给定从动件运动规律下的凸轮轮廓线(凸轮轮廓线即为从动件与主动件相对运动的公共曲线的等距曲线)的等距曲线,进而精确、快捷地构建袋成型包装机热封凸轮三维模型,并以某型号包装机热封凸轮为例对该方法进行了验证。该方法操作简单、直观,只要将热封机构中凸轮与摆杆两部件的运动规律表达清楚,便可应用运动分析结果进行凸轮轮廓等距曲线的绘制,结合Creo强大的参数化功能,还可方便再生模型。该方法可推广应用获取所有完成相对运动的两部件之间的关键曲线,如刀具加工产品的轮廓曲线。

基于Creo Parametric对机械制图教学内容的重造

该文提出了《机械制图》与《三维造型》在教学内容上进行融合的观点,将工程实践中的3D到2D的设计生产理念引入到《机械制图》的教学中,进行了课程的综合,实现了《机械制图》教学内容的重造。

基于Creo Parametric和MATLAB的盘形凸轮机构的设计和分析

以偏置直动滚子从动件盘形凸轮机构为研究对象,根据凸轮从动件的运动规律及理论计算公式,提出一种基于Creo Parametric进行凸轮机构的轮廓曲线设计、建模、装配及运动学分析的方法,并结合MATLAB强大的计算功能绘制压力角随转角的变化曲线,为判断凸轮机构的设计是否具有合理的结构尺寸和良好的运动、力学性能提供了一种新的思路。这种方法具有精度高、快捷、便利的特点。

Enhanced picosecond terahertz wave generation based on cascade effects in a terahertz parametric generator

Enhanced terahertz wave generation via a Stokes cascade process has been demonstrated using picosecond pulse pumped terahertz parametric generation at 1 kHz repetition rate.Clear cascade saturation of terahertz output was observed,and the corresponding cascade-Stokes spectra were analyzed.The maximum terahertz wave average power was 22μW under a pump power of 30 W,whereas the maximum power conversion efficiency was 8×10^(-7)under a pump power of 21 W.The THz power fluctuation was measured to be about 1%in 20 min.This THz parametric source with a relatively stable output is suitable for a variety of practical applications.

Tunable topological interface states via a parametric system in composite lattices with/without symmetric elements

Over the past decades, topological interface states have attracted significant attention in classical wave systems. Generally, research on the topological interface states of elastic waves is conducted in the lattices with symmetric elements. This paper proposes composite lattices with/without symmetric elements, and demonstrates the realization of tunable topological interface states of elastic waves via parametric systems.To quantize the topological characteristics of the bands, a modified Zak phase is defined to calculate the topological invariant by the eigenstates for the lattices with/without symmetric elements. The numerical results show that the tunable frequencies of topological interface states can be realized in composite lattices with/without symmetric elements through the modulation of the parametric excitation frequency. The tunable topological interface states can be introduced into the vibration energy harvesting to design efficient and steady energy harvesting systems.

Parametric instability in the pure-quartic nonlinear Schrödinger equation

We study the nonlinear stage of modulation instability(MI)in the non-intergrable pure-quartic nonlinear Schrödinger equation where the fourth-order dispersion is modulated periodically.Using the three-mode truncation,we reveal the complex recurrence of parametric resonance(PR)breathers,where each recurrence is associated with two oscillation periods(PR period and internal oscillation period).The nonlinear stage of parametric instability admits the maximum energy exchange between the spectrum sidebands and central mode occurring outside the MI gain band.

A Practical Guide to Statistical Tests in the Biomedical Field: From Parametric to Nonparametric, Where and How?

Healthcare decisions are based on scientific evidence obtained from medical studies by gathering data and analyzing it to obtain the best results. When analyzing data, biostatistics is a powerful tool, but healthcare professionals lack knowledge in this field. This lack of knowledge can manifest itself in situations such as choosing the wrong statistical test for the right situation or applying a statistical test without checking its assumptions, leading to inaccurate results and misleading conclusions. With the help of this “narrative review”, the aim is to bring biostatistics closer to healthcare professionals by answering certain questions: how to describe the distribution of data? how to assess the normality of data? how to transform data? and how to choose between nonparametric and parametric tests? Through this work, our hope is that the reader will be able to choose the right test for the right situation, in order to obtain the most accurate results.

Parametric resonance of axially functionally graded pipes conveying pulsating fluid

Based on the generalized Hamilton's principle,the nonlinear governing equation of an axially functionally graded(AFG)pipe is established.The non-trivial equilibrium configuration is superposed by the modal functions of a simply supported beam.Via the direct multi-scale method,the response and stability boundary to the pulsating fluid velocity are solved analytically and verified by the differential quadrature element method(DQEM).The influence of Young's modulus gradient on the parametric resonance is investigated in the subcritical and supercritical regions.In general,the pipe in the supercritical region is more sensitive to the pulsating excitation.The nonlinearity changes from hard to soft,and the non-trivial equilibrium configuration introduces more frequency components to the vibration.Besides,the increasing Young's modulus gradient improves the critical pulsating flow velocity of the parametric resonance,and further enhances the stability of the system.In addition,when the temperature increases along the axial direction,reducing the gradient parameter can enhance the response asymmetry.This work further complements the theoretical analysis of pipes conveying pulsating fluid.

Harmonic balance simulation of the influence of component uniformity and reliability on the performance of a Josephson traveling wave parametric amplifier

A Josephson traveling wave parametric amplifier(JTWPA),which is a quantum-limited amplifier with high gain and large bandwidth,is the core device of large-scale measurement and control systems for quantum computing.A typical JTWPA consists of thousands of Josephson junctions connected in series to form a transmission line and hundreds of shunt LC resonators periodically loaded along the line for phase matching.Because the variation of these capacitors and inductors can be detrimental to their high-frequency characteristics,the fabrication of a JTWPA typically necessitates precise processing equipment.To guide the fabrication process and further improve the design for manufacturability,it is necessary to understand how each electronic component affects the amplifier.In this paper,we use the harmonic balance method to conduct a comprehensive study on the impact of nonuniformity and fabrication yield of the electronic components on the performance of a JTWPA.The results provide insightful and scientific guidance for device design and fabrication processes.

Modularized and Parametric Modeling Technology for Finite Element Simulations of Underground Engineering under Complicated Geological Conditions

The surrounding geological conditions and supporting structures of underground engineering are often updated during construction,and these updates require repeated numerical modeling.To improve the numerical modeling efficiency of underground engineering,a modularized and parametric modeling cloud server is developed by using Python codes.The basic framework of the cloud server is as follows:input the modeling parameters into the web platform,implement Rhino software and FLAC3D software to model and run simulations in the cloud server,and return the simulation results to the web platform.The modeling program can automatically generate instructions that can run the modeling process in Rhino based on the input modeling parameters.The main modules of the modeling program include modeling the 3D geological structures,the underground engineering structures,and the supporting structures as well as meshing the geometric models.In particular,various cross-sections of underground caverns are crafted as parametricmodules in themodeling program.Themodularized and parametric modeling program is used for a finite element simulation of the underground powerhouse of the Shuangjiangkou Hydropower Station.This complicatedmodel is rapidly generated for the simulation,and the simulation results are reasonable.Thus,this modularized and parametric modeling program is applicable for three-dimensional finite element simulations and analyses.

Meta-Auto-Decoder:a Meta-Learning-Based Reduced Order Model for Solving Parametric Partial Differential Equations

Many important problems in science and engineering require solving the so-called parametric partial differential equations(PDEs),i.e.,PDEs with different physical parameters,boundary conditions,shapes of computational domains,etc.Typical reduced order modeling techniques accelerate the solution of the parametric PDEs by projecting them onto a linear trial manifold constructed in the ofline stage.These methods often need a predefined mesh as well as a series of precomputed solution snapshots,and may struggle to balance between the efficiency and accuracy due to the limitation of the linear ansatz.Utilizing the nonlinear representation of neural networks(NNs),we propose the Meta-Auto-Decoder(MAD)to construct a nonlinear trial manifold,whose best possible performance is measured theoretically by the decoder width.Based on the meta-learning concept,the trial manifold can be learned in a mesh-free and unsupervised way during the pre-training stage.Fast adaptation to new(possibly heterogeneous)PDE parameters is enabled by searching on this trial manifold,and optionally fine-tuning the trial manifold at the same time.Extensive numerical experiments show that the MAD method exhibits a faster convergence speed without losing the accuracy than other deep learning-based methods.

基于Mapkey和Excel的一种Creo Parametric二次开发技术

针对目前三维CAD软件Creo Parametric二次开发难度较大和效率不足等问题,主要通过对Mapkey编码及MS Excel两者的关键技术在二次开发中的应用价值进行研究,并用实际操作来完成一个异步模式下简易的软件二次开发,其开发模式高效、简单,最终能够实现工程师的设计自动化。