MEAM Seminar Series Summer 2017

For Spring 2017 Seminars, click here.

Seminars are held on Tuesday mornings beginning at 10:45 am in Room 337, in the Towne Building (unless otherwise noted).

To be added to the MEAM Events mailing list (which sends notifications regarding all departmental seminars and events) please email us at meam-events@lists.seas.upenn.edu.

June 6

Seok Kim, Assistant Professor, Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign

"Transfer Printing for LEGO-like Microassembly and Nanomaterial Integration"

Abstract:

Reversible dry adhesion-based transfer printing provides a highly straightforward pathway to heterogeneous material integration. The speaker presents his recent research outcomes accomplished in his laboratory which has been exploring responsive surfaces, microassembly, and nanomanufacturing technologies. The first part introduces an engineered reversible dry adhesive made of a shape memory polymer and highlights its consumer product-like prototype. The second part shows how his reversible dry adhesive advances transfer printing techniques to enable his microassemly method called micro-LEGO and summarizes the applications of micro-LEGO with the examples not only of 3D heterogeneous micro-structures but also of devices such as a microtoroid resonator, a tip-tilt-piston micromirror, and a RF MEMS switch. Finally, the third part demonstrates his transfer printing techniques to be further exploited in order to pattern and integrate colloidal quantum dot films. The strategies presented in his talk benefit research activities in smart dry adhesives, 3D MEMS, and nano devices.

Bio:

Seok Kim received his B.S. from Pohang University of Science and Technology, M.S. from University of California at Los Angeles, and Ph.D. from Carnegie Mellon University, all in mechanical engineering, and joined the faculty at the University of Illinois at Urbana-Champaign in 2011. His current research interests include biomimetic design of responsive surfaces for reversible dry adhesion and tunable wetting, transfer printing-based microassembly and nanomanufacturing, and 3D MEMS fabrication technologies. He was a recipient of the National Science Foundation CAREER Award in 2014, the ASME Chao and Trigger Young Manufacturing Engineer Award in 2015, and the Young Investigator Grant Award from the Korean–American Scientists and Engineers Association in 2015.


June 13

PhD Seminar
Paul Barclay
, PhD Candidate, University of Pennsylvania
Advisor: Jennifer Lukes

"Molecular Dynamic Study on Fluid Flow and the Fluid-Fluid Interfacial Mobility"

10:45 am, Towne 337

Abstract:

A nonequilibrium molecular dynamics method to induce fluid flow in nanochannels, the insertion-deletion method (IDM), is introduced. IDM inserts and deletes particles within distinct regions in the domain, creating locally high and low pressures. The benefits of IDM are that it directly controls a physically meaningful quantity, the mass flow rate, allows for pressure and density gradients to develop in the direction of flow, and permits treatment of complex aperiodic geometries. Validation of IDM is performed, yielding good agreement with the analytical solution of Poiseuille flow in a planar channel. Comparison of IDM to existing methods indicates that it is best suited for gases, both because it intrinsically accounts for compressibility effects on the flow and because the computational cost of particle insertion is lowest for low-density fluids.

Dual control volume grand canonical molecular dynamics is used to calculate fluid-fluid interfacial mobility from random interface walks. The mobility is calculated from one-dimensional walks of the interface with no driving force by using the fluctuation-dissipation relation similar to the Stokes-Einstein relation. The mobility is calculated with the interfacial mean square displacement as well as with the interfacial velocity autocorrelation function. One liquid-vapor and two liquid-liquid interfaces are simulated to examine the robustness of this method.


June 15

PhD Defense
Ting Yue, Ph.D. Candidate, University of Pennsylvania
Advisor: Noam Lior

"Thermodynamic Analysis for Improving Uunderstanding and Performance of Hybrid Power Cycles Using Multiple Heat Sources of Different Temperatures"

3:00 p.m., Room 227, Towne Building

Abstract:

Past studies on hybrid power cycles using multiple heat sources of different temperatures focused mainly on case studies and almost no general theory about this type of systems has been developed. This dissertation is a study of their general thermodynamic performance, with comparisons to their corresponding single heat source reference systems. The method used in the dissertation was step-wise: to first analyze the major hybrid power cycles (e.g. Rankine, Brayton, Combined Cycles, and their main variants) thermodynamically, without involving specific operation parameter values, and develop some generalized theory that is at least applicable to each type of system. The second step was to look for commonalities between these theories and develop the sought generalized theory based on these commonalities. A number of simulation case studies were performed to help the understanding and confirm the thermodynamic results. Exergo-economic analysis was also performed to complement the thermodynamic analysis with consideration of externalities, and was compared to the conventional economic analysis method. The generalized expressions for the energy/exergy efficiency differences between the hybrid and the corresponding single heat source systems were developed. The results showed that the energy and exergy efficiencies of the hybrid systems are higher than those of their corresponding single heat source reference systems if and only if the energy/exergy conversion efficiency (defined in the dissertation) of the additional heat source (AHS, can be any heat source that has lower temperature) is larger than that of the original heat source. Sensitivity analysis results showed the relations between the temperature and heat addition rate of the AHS and the energy/exergy efficiency of the hybrid systems. Other big advantages of hybrid systems, i.e. the effects on replacement of fossil fuel by renewable, nuclear and waste energy, lower emissions and depletion of fossil fuel, were revealed in the economic analysis, by considering the cost reduction from fuel saving and carbon tax. Simple criteria were developed to help compare the hybrid and reference systems and determine under which conditions the hybrid systems will have better thermodynamic or economic performance than the reference ones. The results and criteria can be used to help design the hybrid systems to achieve higher energy and/or exergy efficiencies and/or lower levelized electricity cost (LEC) before detailed design or simulation or experiment. So far, 3 archival journal papers and 3 conference papers were published from this dissertation work.


June 20

PhD Seminar
James Hilbert, PhD Candidate, University of Pennsylvania
Advisor: Robert Carpick

"Carbon coatings under extreme conditions: Understanding and addressing the thermal instability and humidity-dependent tribology of hydrogenated amorphous carbon films by using silicon and oxygen as dopants"

10:45 am, Towne 337

Abstract:

Hydrogenated amorphous carbon (a-C:H) films are amorphous materials made of hydrogen and carbon bonded in both sp2 and sp3 configurations. These films are notable for their high hardness (10-16 GPa, compared to 1-1.5 GPa for steel), ease of application to a wide range of substrates, and good tribological performance (low friction and wear). However, they suffer from significant limitations. First, a-C:H becomes unstable above 150°C, preventing its use in important technological applications, such as heat assisted magnetic recording (HAMR) disk drives. Second, the low friction and wear is only maintained in dry and vacuum conditions. This prevents their use as protective coatings in applications where the humidity may vary such as use in aerospace components which need to function in and outside the atmosphere.

To understand and potentially address these limitations, we consider the effect of adding silicon and oxygen to a-C:H films, since prior experimental evidence shows that this can significantly increases thermal stability, and help maintain low friction and wear when sliding in humid environments. However, the mechanisms for these improvements are unknown.

Reactive molecular dynamics (MD) simulations using the ReaxFF potential were performed on undoped a-C:H and a-C:H doped with Si and O (a-C:H:Si:O) to explore the effect on thermal stability. Atomistic thermal degradation pathways were examined to understand the origins of the enhanced thermal stability endowed by SiOx-doping. As in experiments, the simulated a-C:H:Si:O demonstrated increased thermal stability compared to conventional a-C:H. The primary thermal degradation pathway in undoped a-C:H was observed to be the breaking of tensile strained C-C bonds resulting in a transformation of sp3 to sp2-hybridized carbon. The presence of Si suppresses this mechanism by decreasing the frequency of highly strained C-C bonds in the unannealed structure. This is due to the longer C-Si equilibrium bond length compared to C-C bonds, which allows the Si-doped films to accommodate higher structural disorder.

To explore the improvement in the tribological properties, we measured coefficients of friction varying from approximately 0.05 in dry environments (RH < 5%) to 0.15 in humid air when sliding against steel, significantly better than prior observations for undoped a-C:H films. The wear rate is also environmentally-dependent and typically correlated with friction. The friction and wear behavior is controlled by the formation of adhesive junctions between the a-C:H:Si:O films and the steel balls. Possible mechanisms underlying this behavior will be discussed.


June 27

PhD Seminar
Chenchen Liu, PhD Candidate, University of Pennsylvania
Advisor: Celia Reina

"Multiscale Modeling and Design of Acoustic Metamaterials"

10:45 am, Towne 337

Abstract:

Elastic composite/metamaterials have exhibited a rapid increase of interest due to their surprising dynamic properties, such as sub-wavelength band gaps, negative effective elastic constant and/or density and frequency-dependent elastic anisotropies. The design and optimization of these novel materials architectures call for an enhanced understanding of the microstructure-properties relations when micro-inertia effects may start to play a macroscopically observable role.

In this talk, we present a variational coarse-graining framework for heterogeneous media, that allows for a seamless transition from the traditional static scenario to dynamic loading conditions, while being applicable to general material behavior as well as to discrete or continuous representations of the material and its deformation, e.g., finite element discretizations or atomistic systems. The method automatically delivers the macroscopic equations of motion, which are in general not in closed form, together with the generalization of Hill's averaging relations to the dynamic setting. We further demonstrate with a proof of concept example, that the proposed theoretical framework can be used to perform multiscale numerical simulations in the spirit of FE2 methods. The results are compared with standard single-scale finite element simulations, showcasing the capability of the method to capture the dispersive nature of the medium in the range of frequencies permitted by the multiscale strategy.

We further present material architecture designs based on resonant hierarchical structures. These systems are promising to generate multiple band gaps thanks to their inherent multiple scales, and are here investigated systematically as a function of the relevant parameters in idealized lattice systems. Based on these results, we propose graded hierarchical designs that deliver phononic crystals with enhanced bandwidth. These theoretical analyses based on lattice system are then certified using continuum models and finite element simulations.

June 28

MEAM Special Seminar
Thomas C. Hull, Associate Professor of Mathematics, Western New England University

"Self-foldability and Rigid Origami"

10:00 am, Towne 337

Abstract:

When actuating a rigid origami mechanism by applying driving forces (moments) at the crease lines, we often confront a bifurcation problem where it is not possible to predict the way the model will fold when it is in a flat state. In this talk we develop a mathematical model of self-folding and propose the concept of self-foldability of rigid origami when a set of driving forces are given. In particular, we desire to design a driving force such that a given crease pattern can uniquely self-fold to a desired mode without getting caught in a bifurcation. We provide necessary conditions for self-foldability that serve as tools to analyze and design self-foldable crease patterns.

Using these tools, we analyze the unique self-foldability of several fundamental patterns and demonstrate the usefulness of the proposed model for mechanical design. This is joint work with Tomohiro Tachi (Univ. of Tokyo).

Bio:

Thomas Hull is an associate professor of mathematics at Western New England University. He has been researching new and collecting old results on the mathematics of paper folding since the early 1990s and is one of the foremost experts on the subject.


July 4

Independence Day - NO SEMINAR


July 11

PhD Seminar
Ruiyuan Ma, PhD Candidate, University of Pennsylvania
Advisor: Jennifer Lukes

"Thermal Conductivity Calculation in Nano Phononic Crystals"

10:45 am, Towne 305

Abstract:

Superlattices and nano phononic crystals have attracted significant attention due to their low thermal conductivities and their potential application as thermoelectric materials. A widely used expression to calculate thermal conductivity, presented by Klemens and expressed in terms of the relaxation time by Callaway and Holland, originates from the Boltzmann transport equation. In its most general form, this expression involves a direct summation of the heat current contributions from individual phonons of all wavevectors and polarizations in the first Brillouin zone. In common practice, the expression is simplified by making an isotropic assumption that converts the summation over wavevector to an integral over wavevector magnitude. The isotropic expression has been applied to superlattices and phononic crystals, but its validity for diff erent supercell sizes has not been studied. In this work, the isotropic and direct summation methods are used to calculate the thermal conductivities of bulk Si, Si/Ge superlattices, and Si/Ge quantum dot superlattices. The results show that the differences between the two methods increase substantially with supercell size. These differences arise because the vibrational modes neglected in the isotropic assumption provide an increasingly important contribution to the thermal conductivity for larger supercells. For thermal conductivity calculations in superstructures, the isotropic assumption is signicantly in error and direct summation calculations are recommended.


July 18

PhD Seminar
Mohammed Asaduzzaman, PhD Candidate, University of Pennsylvania
Advisor: Howard Hu

"Interfacial Wave Dynamics of Core-Annular Flow of Two Fluids"

10:45 am, Towne 305

Abstract:

In Core-Annular flow of two different fluids, for a set of suitable flow conditions, various shapes of saturated waves such as Bamboo waves, Snakes, and Cork-Screw waves are observed. Some of the dominant parameters such as thickness ratio of the fluid, Reynolds number, viscosity ratio, density ratio, interfacial surface tension, and the direction of gravitational forces determine the final shape of the saturated wave and their ultimate stability in a non-linear regime.

When the flow rate ratio is high, sometimes it is difficult to determine the differences between the final shape of the waves for up-flow and down-flow. For some combinations of thickness ratio, viscosity ratio, density ratio, Reynolds number and surface tension, waves tend to break down and a bubble starts to form. Interfacial surface tensions between these two fluids play a very important role to stabilize the waves from breaking down.

In this study, new sets of waves were discovered for core-annular flow, which modulate at certain flow parameter ranges. The critical parameter ranges are identified where the waves shift from saturated non-modulated wave and bifurcate into saturated modulated waves. A thorough analysis is performed for the first time to depict the windows of these critical parameters at which this transition takes place. A bifurcation diagram is constructed to capture the regime. A detailed wave shape analysis is performed to characterize these wave shapes and their periods of oscillation.

Due to challenges associated with large computational domain and an enormous computational power requires to resolve the interfacial instability, a three-dimensional true non-axisymmetric model was never studied before. For the first time, effort is being undertaken to construct a viable 3-D Core-Annular flow. Computational Fluid Dynamics package ANSYS Fluent™ is used for this analysis. Three dimensional models for both Up-flow and Down-flow were constructed and a novel explanation is presented to distinguish between the Bamboo waves, Cork-Screw waves, and Snake waves. The sensitivity of down flow on initial conditions were also verified with 3-D models on some parameter space from selected publication.


July 20

Special PhD Seminar
Sarah Tang
, PhD Candidate, University of Pennsylvania
Advisor: Vijay Kumar

"Trajectory Generation for Agile Aerial Robot Teams"

1:00 pm, Levine 307

Abstract:

In the past decades, many techniques have been proposed for planning for multi-robot systems. However, research thus far has focused disproportionately on finding optimal solutions for systems of simple first- or second-order robots. Contrastingly, real-world multi-robot systems for tasks such as drone delivery, warehouse management, and cooperative construction often require more complex vehicles. Robots can have articulated bodies, higher-order and nonlinear dynamics, be under-actuated, and are subject to motor constraints. This precludes the use of traditional planning techniques and instead, requires development of multi-robot trajectory generation algorithms that incorporate information about agents’ geometries and dynamics.

This talk will describe safe and complete algorithms for trajectory generation for teams of quadrotors. In particular, we will solve the labeled multi-robot planning, where robots must navigate from their start positions to fixed, noninterchangeable goal positions. This problem often arises when each robot has a unique payload or sensor package that is required to complete the task at the specified goal position. We then extend this algorithm to allow each robot to transport a cable-suspended payload. Finally, we explore extensions of this algorithm into obstacle-filled environments.


July 25

PhD Seminar
Monroe D. Kennedy III, PhD Candidate, University of Pennsylvania
Advisor: Vijay Kumar

"Human-Robot Cooperative Carrying"

10:45 am, Towne 305

Abstract:

As the market for commercial robotics increases, a useful but underdeveloped platform is the humanoid robot characterized by the combination of a manipulator and mobile platform. A very important capability for such a system is the ability to assist a human counterpart in carrying large (and possibly heavy) objects in cluttered environments. This ability for a robot to cooperatively carry has applications in disaster relief, assisted living, and even the laboratory/general work environment. While a lot of work has been done in this area, most existing approaches rely on robot passivity and depend on the human to perform planning and move in such a way that leverages the robot support. Hence an open area of research is providing the robot with ability to ascertain the intention of the human in the carrying task, perceive the environment, and provide intelligent support while allowing the human to 'lead', effectively performing as a cooperative human counterpart.

In this talk, the carrying task will be examined from three perspectives: nature-nature, robot-robot and nature-robot. We will discuss how Aphaenogaster Cockerelli ants cooperatively work together to transport sensors capable of detecting their force and motion, and see what data suggests in terms of their ability to reach consensus. We will then discuss the minimum amount of information robot systems must share with each other to efficiently carry. Then we will discuss an algorithm that allows a robot to ascertain where the human is attempting to move and allow the robot to passively support and follow the human intention from either a leading or following position. Finally we will discuss how this cooperative carrying capability fits into the big picture of assisting humanoid robots by examining parallel abilities and a possible system architecture.


July 28

Special PhD Seminar
Sikang Liu
, PhD Candidate, University of Pennsylvania
Advisor: Vijay Kumar

"Search-based Motion Planning for Micro Aerial Vehicles"

11:00 am, Levine 307

Abstract:

A fully autonomous flying robot can be widely used for cargo delivery, region surveillance, civilian rescue and many other tasks. Autonomous navigation of micro aerial vehicles or quadrotors in complicate and unstructured environments is a challenging but attractive problem, it requires the quadrotor not only to detect obstacles with on-board sensing, but also to plan and execute collision-free and dynamically feasible trajectories. The fundamental and key component of such an autonomy is the efficient method to generate those trajectories. Many works have been proposed to generate trajectories for the quadrotor considering its agility and complex dynamics, but none of these works is able to simultaneously achieve completeness, global optimality and real-time computation.

In our latest work, we proposed an advanced technique for calculating global optimal and resolution complete trajectories that is sufficient fast for real-time implementation. We adopted the idea from lattice search and linear quadratic minimum time control (LQMT) to convert a trajectory optimization problem to a graph search problem. Based on that, we designed heuristics based on the explicit solution of a LQMT problem that dramatically accelerate the searching process but in the meanwhile maintain trajectories’ optimality and completeness. We demonstrated this motion planning method on our quadrotor platform to complete various navigation tasks including the DARPA Fast Lightweight Autonomy competition.


August 1

PhD Seminar
Mickey Whitzer, PhD Candidate, University of Pennsylvania
Advisor: Vijay Kumar

"Formation Control and Coordination for Teams of Nonholonomic Robots"

10:45 am, Towne 337

Abstract:

Multi-robot coordination and path planning lie at the core of applications such as search and rescue, mobile surveillance, and automated fulfillment centers. Existing methods enable teams of robots to collaborate and plan safe trajectories to complete their objectives. However, prior work focuses mostly on holonomic platforms, or on tracking straight-line trajectories. Multi-robot coordination becomes increasingly complex when considering vehicles with turning constraints, such as car-like vehicles, or fixed-wing aircrafts. This talk will discuss algorithms for the coordination of kinematically constrained robots.

I will present an algorithm for the in-flight and on demand formation control of a team of fixed-wing aircraft. This algorithm enables robots to autonomously achieve formations defined by a user during mission execution. This algorithm also presents an efficient means of formation maintenance, only requiring knowledge of the parameterized index of a virtual or real leader. Robots such as the fixed-wing aircraft discussed here, have a turning constraint, making it difficult to generate the collision-free assignment of robots to desired goal locations. Recent work on the nonholonomic robot assignment problem will also be presented. This work seeks to achieve nonholonomic robot assignment with guarantees on collision avoidance.


August 8

NO SEMINAR


August 15

PhD Seminar
Yuejun Yan, PhD Candidate, University of Pennsylvania
Advisor: Noam Lior

"Gaseous Fuel Combustion Irreversibility Analysis and Reduction "

10:45 am, Towne 337

Abstract:

Combustion is widely used in energy supply process and it is of great importance to seek for the efficient use. Exergy analysis revealed that approximately 20%-30% of the useful energy (i.e., exergy) of the fuel is destroyed in combustion, where irreversibilities take place. Pursuit and discovery of ways to reduce combustion irreversibility is one of the highest-ranking objectives in combustion research to reduce combustion emissions, fuel depletion, and consumer prices. However, detailed knowledge and understanding of the causes, locations and magnitudes of these irreversibilities, is still incomplete due to the fact that combustion involves interrelated simultaneous effects chemical reaction, viscous dissipation, mass diffusion and heat transfer, all of which generate irreversibilities. In previous investigation, two approaches, the IAM (intrinsic analytical method) and the HFIM (heuristic finite increment method, firstly proposed and developed by Dunbar and Lior in 1991) are applied for combustion irreversibility analysis.

In this talk, a further and much deeper investigation of hydrogen-air combustion irreversibility using the HFIM is introduced to make the application of HFIM more systematic and simpler. A creative application of the improved HFIM to find out path with least overall combustion irreversibility is introduced. Combustion irreversibility distribution in the main three subprocesses, chemical reaction, mass diffusion and heat transfer are analyzed. In addition to the further development of the HFIM, combustion irreversibility analysis using the IAM is also carried out and the results are used as reference results to compare with those using HFIM. Both methods indicate potential to reduce overall and subprocess irreversibility and will be pointed out in this talk.


August 22

PhD Seminar
Xiaoguai Li, PhD Candidate, University of Pennsylvania
Advisor: Celia Reina

"Non-equilibrium Material Behavior: From Particles to Continuum Description"

10:45 am, Towne 337

Abstract:

Non-equilibrium material processes, like thermal transport, diffusion or phase transitions are ubiquitous in nature and industrial applications. However, their modeling at the continuum level is largely dominated by phenomenology, and classical relations for their description often fails to describe complex material systems. This talk will cover two studies aimed at gaining a better understanding of the limitations of current modeling strategies and provide insight into non-equilibrium material behavior. First, we examine the self-consistency of continuum approaches for irreversible phenomena, and we do so in the context of interface thermodynamics and kinetics. The results will reveal some inconsistencies that will motivate the multiscale analyses of non-equilibrium processes. Our second effort will be aimed at the simultaneous spatio-temporal coarse-graining of particle dynamics to deliver the thermomechanics equations of motion. This perspective, different from classical statistical mechanics, will recover fundamental concepts and relations in equilibrium thermodynamics and enable the extension to more complex systems, such as granular media, often described by means of two temperatures.


August 28

PhD Seminar
Lin Chen, PhD Candidate, University of Pennsylvania
Advisor: Igor Bargatin

"Microstructures and Mechanical Metamaterials for Energy Conversion and Other Applications"

10:45 am, Towne 309

Abstract:

Deep reactive-ion etching (DRIE) and atomic layer deposition (ALD) are two advanced micro/nano-fabrication technologies, which enable the manufacturing of a variety of novel devices. The Bosch process, considered as the most commonly used DRIE technique, can be employed to produce nearly vertical features with high aspect ratios. ALD is a thin film deposition method that uses sequential and self-limiting reactions between precursors and surface material. As a result, ALD can be used for depositing controllable, conformal and ultrathin films even on high aspect ratio structures. By using both DRIE and ALD, we demonstrated several new structures and materials with unprecedented properties. In particular, we fabricated and characterized segmented expansion anode arrays and anode-cathode insulating standoffs, which are both important components of microcap thermionic energy converters (TECs). We also fabricated and characterized a hollow ALD sandwich plate mechanical metamaterial (PMM), which we call nanocardboard (NCB). This ultrathin, lightweight, flat, stiff and robust NCB structure with macroscopic dimensions can be potentially used for ultra-sensitive atomic-force microscopy (AFM) probes, microflyer structural materials, etc.

August 29

PhD Seminar
Dawei Song, PhD Candidate, University of Pennsylvania
Advisor: Pedro Ponte

"Homogenized Response of Porous Single Crystals and Polycrystals"

10:45 am, Towne 227

Abstract:

Most metals and minerals---both man-made and natural---are polycrystalline aggregates of single crystals containing voids, cracks and other inhomogeneities. It is then of great interest to be able to characterize the effective response of such materials in terms of the known properties of their constituents and statistical information about their microstructures. However, the strong nonlinearity of the relevant deformation mechanisms (e.g., dislocation motion and interaction), as well as the extreme contrast in the constituent properties of these materials make it particularly challenging to develop reliable constitutive models for their macroscopic behavior.

In this talk, I will present a new homogenization-based constitutive model to estimate the macroscopic response of heterogeneous materials consisting of aggregates of viscoplastic single-crystal grains and other inhomogeneities such as microvoids. The model makes use of the effective behavior of a linear comparison composite (LCC), whose local property is determined by a suitably designed variational principle, to determine the effective behavior of the actual nonlinear composites. The resulting estimates for the macroscopic response are guaranteed to be exact to second-order in the heterogeneity contrast, and to satisfy known bounds. In addition, consistent homogenization estimates may be obtained for the average deformation fields in the composites, which can in turn be used to determine the evolution of the microstructure at finite-strain deformations. Applications will be given for both solid polycrystals and porous single crystals, and the predictions of the model will be compared with numerical results available in the literature.