Accepted Manuscripts

Anna Y Zemlyanova and Sonia Mogilevskaya
J. Appl. Mech   doi: 10.1115/1.4041499
The problem of an infinite isotropic elastic space subjected to uniform far-field load and containing an isotropic elastic spherical inhomogeneity with Steigmann-Ogden interface is considered. The interface is treated as a shell of vanishing thickness possessing surface tension as well as membrane and bending stiffnesses. The constitutive and equilibrium equations of the Steigmann-Ogden theory for a spherical surface are written in explicit forms. Closed-form analytical solutions are derived for two cases of loading conditions - the hydrostatic loading and deviatoric loading with vanishing surface tension. The single-inhomogeneity based estimates of the effective properties of macroscopically isotropic materials containing spherical inhomogeneities with Steigmann-Ogden interfaces are presented. It is demonstrated that, in the case of vanishing surface tension, the Steigmann-Ogden model describes a special case of the thin and stiff uniform interphase layer.
TOPICS: Surface tension, Hydrostatics, Stress, Equilibrium (Physics), Membranes, Shells
Arghavan Louhghalam, Mazdak Tootkaboni, Takeru Igusa and Franz-Josef Ulm
J. Appl. Mech   doi: 10.1115/1.4041500
A major contributor to rolling resistance is road roughness-induced energy dissipation in vehicle suspension systems. We identify the parameters driving this dissipation via a combination of dimensional analysis and asymptotic analysis. We begin with a mechanistic model and basic random vibration theory to relate the statistics of road roughness profile and the dynamic properties of the vehicle to dissipated energy. Asymptotic analysis is then used to unravel the dependence of the dissipation on key vehicle and road characteristics. Finally, closed form expressions and scaling relations are developed that permit a straightforward application of the proposed road-vehicle interaction model for evaluating network-level environmental footprint associated with roughness-induced energy dissipation.
TOPICS: Surface roughness, Energy dissipation, Vehicles, Roads, Rolling friction, Statistics as topic, Motor vehicles, Random vibration, Suspension systems, Dimensional analysis
Ming Dai, Min Li and Peter Schiavone
J. Appl. Mech   doi: 10.1115/1.4041469
We consider the plane deformations of an infinite elastic solid containing an arbitrarily-shaped compressible liquid inhomogeneity in the presence of uniform remote in-plane loading. The effects of residual interface tension and interface elasticity are incorporated into the model of deformation via the complete Gurtin-Murdoch (G-M) interface model. The corresponding boundary value problem is reformulated and analyzed in the complex plane. A concise analytical solution describing the entire stress field in the surrounding solid is found in the particular case involving a circular inhomogeneity. Numerical examples are presented to illustrate the analytic solution when the uniform remote loading takes the form of a uniaxial compression. It is shown that using the simplified G-M interface model instead of the complete version may lead to significant errors in predicting the external loading-induced stress concentration in gel-like soft solids containing submicro- (or smaller) liquid inhomogeneities.
TOPICS: Deformation, Solids, Stress, Stress concentration, Boundary-value problems, Compression, Errors, Tension, Elasticity
Xiu Jia, Tomas Grejtak, Brandon A. Krick and Natasha Vermaak
J. Appl. Mech   doi: 10.1115/1.4041470
Considerable effort has been made to model, predict, and mitigate wear as it has significant global impact on the environment, economy, and energy consumption. This work proposes generalized foundation-based wear models and a simulation procedure for single material and multi-material composites subject to rotary or linear abrasive sliding wear. For the first time, experimental calibration of foundation parameters and asymmetry effects are included. An iterative wear simulation procedure is outlined that considers implicit boundary conditions to better reflect the response of the whole sample and counter-body system compared to existing models. Key features such as surface profile, corresponding contact pressure evolution and material loss can be predicted. For calibration and validation, both rotary and linear wear tests are conducted on purpose-built tribometers. In particular, an experimental calibration procedure for foundation parameters is developed based on a Levenberg-Marquardt optimization algorithm. This procedure is valid for specific counter-body and wear systems using experimentally measured steady-state worn surface profiles. The calibrated foundation model is validated by a set of rotary wear tests on different bi-material composite samples. The established efficient and accurate wear simulation framework is well suited for future design and optimization purposes.
TOPICS: Wear, Simulation, Calibration, Composite materials, Wear testing, Tribometers, Pressure, Energy consumption, Optimization algorithms, Steady state, Design, Economics , Optimization, Boundary-value problems
Zibin Zhang and Jizeng Wang
J. Appl. Mech   doi: 10.1115/1.4041471
Specific adhesion of soft elastic half spaces via molecular bond clusters has been extensively studied in the past ten years. In this study, the adhesion of a soft elastic solid with finite size is considered aiming to investigate how their size and shape may affect the adhesion strength. To model this problem, plane strain assumption is adopted to describe the deformation of the elastic solid. This deformation couples the stochastic behavior of adhesive bonds, for which we have considered the mean field treatment based on the classical Bell theory. Numerical solutions have revealed that besides the elastic modulus, size of the elastic solid and spatial arrangement of the bond clusters are all crucial factors in mediating the adhesion strength. Most interestingly, there clearly exists an optimal size/shape of the elastic solid that corresponds to the largest adhesion strength. These findings provide new insights and inspirations in understanding various phenomena of cellular adhesion, and designing advanced functional biomaterials.
TOPICS: Solids, Adhesion, Deformation, Shapes, Adhesives, Biomaterials, Space, Design, Elastic moduli, Plane strain
Zhe Chen, Tonghao Wu, Guodong Nian, Yejie Shan, Xueya Liang, Hanqing Jiang and Shaoxing Qu
J. Appl. Mech   doi: 10.1115/1.4041415
Energy absorption structures are widely used in many scenarios. Thin-walled members have been heavily employed to absorb impact energy. This paper presents a novel, Ron Resch origami pattern inspired energy absorption structure. Experimental characterization and numerical simulations were conducted to study the energy absorption of this structure. The results show a new collapse mode in terms of energy absorption featuring multiple plastic hinge lines, which lead to the peak force reduction and larger effective stroke, as compared with the classical honeycomb structure. Overall, the Ron Resch origami-inspired structure and the classical honeycomb structure are quite complementary as energy absorption structures.
TOPICS: Absorption, Honeycomb structures, Collapse, Experimental characterization, Origami-inspired design, Hinges, Computer simulation
Yupeng Zhang, Jeffrey Hart and Alan Needleman
J. Appl. Mech   doi: 10.1115/1.4041352
The plastic properties that characterize the uniaxial stress-strain response of a plastically isotropic material are not uniquely related to the indentation force versus indentation depth response. We consider results for three sets of plastic material properties that give rise to essentially identical curves of indentation force versus indentation depth in conical indentation. The corresponding surface profiles after unloading are also calculated. These computed results are regarded as the ``experimental'' data. A simplified Bayesian-type statistical approach is used to identify the values of flow strength and strain hardening exponent for each of the three sets of material parameters. The effect of fluctuations (``noise'') superposed on the ``experimental'' data is also considered. We build the database for the Bayesian-type analysis using finite element calculations for a relatively coarse set of parameter values and use interpolation to refine the database. A good estimate of the uniaxial stress-strain response is obtained for each material both in the absence of fluctuation and in the presence of sufficiently small fluctuations. Since the indentation force versus indentation depth response for the three materials is nearly identical, the predicted uniaxial stress-strain response obtained using only surface profile data differs little from what is obtained using both indentation force versus indentation depth and surface profile data. The sensitivity of the representation of the predicted uniaxial stress-strain response to fluctuations increases with increasing strain hardening. We also explore the sensitivity of the predictions to the degree of database refinement.
TOPICS: Plasticity, Stress, Fluctuations (Physics), Databases, Work hardening, Plastics, Interpolation, Finite element analysis, Flow (Dynamics)
Caihua Zhou, Shizhao Ming, Tong Li, Bo Wang and Mingfa Ren
J. Appl. Mech   doi: 10.1115/1.4041317
The cruciforms are widely employed as energy absorbers in ships and offshore structures, or basic components in sandwich panel and multi-cell structure. The kirigami approach is adopted in the design of cruciform in this paper for the following reasons. First, the manufacture process is simplified. Second, it can alter the stiffness distribution of a structure to trigger desirable progressive collapse modes (PCMs). Third, the kirigami pattern can be referred as a type of geometric imperfection to lower the initial peak force during impact. Experiments and numerical simulations were carried out to validate the effectiveness of kirigami approach for cruciform designs. Numerical simulations were carried out to perform comparative and parametric analyses. The comparative studies among single plate (SP), single plate with kirigami pattern (SPKP) and kirigami cruciform (KC) show that the normalized mean crushing force of KC is nearly two times higher than those of SP and SPKP, whereas the normalized initial peak force of KC reduces by about 20%. In addition, the parametric analyses suggest that both the parameters controlling the overall size (i.e., the global slenderness and local slenderness) and those related to the kirigami pattern (i.e., the length ratio, and the relative position ratio) could significantly affect the collapse behavior of the cruciforms.
TOPICS: Computer simulation, Absorption, Offshore structures, Phase change materials, Design, Collapse, Ships, Stiffness
Xin Lei, Chang Liu, Zongliang Du, Weisheng Zhang and Xu Guo
J. Appl. Mech   doi: 10.1115/1.4041319
In the present work, it is intended to discuss how to achieve real time structural topology optimization (i.e., obtaining the optimized distribution of a certain amount of material in a prescribed design domain almost instantaneously once the objective/constraint functions and external stimuli/boundary conditions are specified), an ultimate dream pursued by engineers in various disciplines, using machine learning (ML) techniques. To this end, the so-called Moving Morphable Component (MMC)-based explicit framework for topology optimization is adopted for generating training set and supported vector regression (SVR) as well as K-nearest- neighbors (KNN) ML models are employed to establish the mapping between the design parameters characterizing the layout/topology of an optimized structure and the external load. Compared with existing approaches, the proposed approach can not only reduce the training data and the dimension of parameter space substantially, but also has the potential of establishing engineering intuitions on optimized structures corresponding to various external loads through the learning process. Numerical examples provided demonstrate the effectiveness and advantages of the proposed approach.
TOPICS: Machinery, Optimization, Topology, Stress, Design, Engineering disciplines, Engineers, Dimensions, Boundary-value problems

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