Annular Membrane Research Articles

Plastic instability of annular crystalline membrane in circular confinement.

Understanding the mechanical instabilities of two-dimensional membranes has strong connection to the subjects of structure instabilities, morphology control, and materials failures. In this work, we investigate the plastic mechanism developed in the annular crystalline membrane system for adapting to the shrinking space, which is caused by the controllable gradual expansion of the inner boundary. In the process of plastic deformation, we find the continuous generation of dislocations at the inner boundary and their collective migration to the outer boundary; this neat dynamic scenario of dislocation current captures the complicated reorganization process of the particles. We also reveal the characteristic vortex structure arising from the interplay of topological defects and the displacement field. These results may find applications in the precise control of structural instabilities in packings of particulate matter and covalently bonded systems.

Curved and Annular Diaphragm Coupled Piezoelectric Micromachined Ultrasonic Transducers for High Transmit Biomedical Applications.

In this paper, we present a novel three-dimensional (3D) coupled configuration of piezoelectric micromachined ultrasound transducers (pMUTs) by combing a curved and an annular diaphragm for transmit performance optimization in biomedical applications. An analytical equivalent circuit model (EQC) is developed with varied excitation methods to incorporate the acoustic-structure coupling of the curved and annular diaphragm-coupled pMUTs (CAC-pMUTs). The model-derived results align well with the reference simulated by the finite element method (FEM). Using this EQC model, we optimize the key design parameters of the CAC-pMUTs in order to improve the output sound pressure, including the width of the annular membrane, the thickness of the passive layer, and the phase difference of the driving voltage. In the anti-phase mode, the designed CAC-pMUTs demonstrate a transmit efficiency 285 times higher than that of single annular pMUTs. This substantial improvement underscores the potential of CAC-pMUTs for large array applications.

Improved Power Series Solution of Transversely Loaded Hollow Annular Membranes: Simultaneous Modification of Out-of-Plane Equilibrium Equation and Radial Geometric Equation

The ability to accurately predict the shape of a transversely loaded hollow annular membrane is essential to the design of bending-free hollow annular shells of revolution, which requires a further improvement in the hollow annular membrane solution to meet the needs of this accurate prediction. In this paper, the large deflection problem of a transversely loaded hollow annular membrane is reformulated by simultaneously modifying the out-of-plane equilibrium equation and radial geometric equation, and a newer and more refined power series solution is derived. The reason why the classical radial geometry equation induces errors is revealed. The convergence and asymptotic behavior of the power series solution obtained is analyzed numerically. The newly derived solution is compared with the two previously derived solutions graphically, showing that the newly derived solution performs basically as well as expected. In addition, the anticipated use of the hollow and not-hollow annular membrane solutions for the design application of bending-free annular shells of revolution is discussed.

A finite element modeling for anisotropic dielectric elastomer energy harvesters with inhomogeneous displacement fields

In this paper, we are to investigate the effects of imparting anisotropy to dielectric elastomers (DEs) to evaluate the promising capabilities of this phenomenon in energy harvesting (EH) enhancement. To this end, we employ the principle of virtual work to obtain the governing equations and the boundary conditions of dielectric elastomers at finite strains. As for the material law, it incorporates three parts, including an isotropic, an anisotropic, and an electric one with no modes of dissipation. Having to deal with inhomogeneous displacement fields necessitates the employment of finite element (FE) simulations. Moreover, a staggered algorithm has been put into use which is capable of reducing computational expense while producing the same results as that of a fully coupled solution. Further, F-bar method has been selected to alleviate the issue of volumetric locking. The aforementioned finite element implementation is conducted through a computer program. It is noteworthy that all the terms involved in FE modeling, particularly electroelastic moduli and the terms originated from the follower load assumption are fully derived. Three energy harvesting applications, including a cylindrical tube, a diaphragm, and an annular membrane which satisfy the axisymmetric assumptions, are investigated. In the interest of verifying the developed axisymmetric element, the finite element results have been compared with that of analytical ones for a one-dimensional homogenous actuation problem. Intended to reveal the efficacy of imparting anisotropy to DEs in EH, we fix all the other contributing factors in the energy harvesting cycle for each application. As a result, corresponding isotropic and anisotropic cases become possible whose only difference is in the existence or absence of anisotropic fibers. Eventually, through numerical simulations it is proved that imparting anisotropy to dielectric elastomers in most cases culminates in favor of energy harvesting. Particularly, the maximum amount of relative energy harvesting difference of corresponding isotropic and anisotropic cases for the cylindrical tube, the diaphragm, and the annular membrane is achieved to be 27.75%, 10.61%, and 19.76%, respectively, in favor of the anisotropic cases.

Theoretical, numerical and experimental investigation into vibration characteristics for composite structures of an annular membrane internally connected with a piezoceramic disk

Abstract This work analyzed the vibration characteristics of an annular membrane internally connected with a piezoceramic disk theoretically, numerically and experimentally. The general solution for the free vibration of an annular membrane under uniform tension was derived. Then, the displacement solutions for the piston modes and coupled modes of an annular membrane internally connected with a piezoceramic disk were derived. Two plate theories, Kirchhoff and Mindlin plate theories, were used to simulate the piezoceramic disk. The theoretical results are compared with the numerical results obtained from two finite element software packages: ABAQUS and COMSOL. The amplitude-fluctuation electronic speckle pattern interferometry was used to measure the resonant frequencies and associated mode shapes of five different type specimens with different sizes. Good agreements of dynamic characteristics determined by theoretical analysis, experimental measurements, and numerical calculation are presented for the annular membrane internally connected with piezoceramic disk structures.

Pilot-scale nanofiltration vibratory shear enhanced processing (NF-VSEP) for the improvement of the separation and concentration of compounds of biotechnological interest from tortilla industry wastewater (nejayote)

The aim of the present work was to evaluate the performance of a pilot-scale nanofiltration vibratory shear enhanced processing (NF-VSEP) coupled to an enzymatic/flocculating system to recover, separate, and concentrate compounds of biotechnological interest contained in nejayote, such as arabinoxylans (AXs), hydroxycinnamic acids and reducing sugars (RS). Enzymatic starch granules hydrolysis, flocculation of remaining suspended particles and microfiltration pretreatments resulted in a robust, reproducible, and efficient technologies to completely remove total suspended solids (TSS) from nejayote. The free-TSS nejayote was submitted to the first NF-VSEP module (annular flat sheet polyethersulfone membranes, 1,000 Da MWCO) to separate and concentrate long-chain AXs. At the end of the process, a volume reduction factor (VRF) of 7.4 was achieved, increasing the AXs concentration in the retentate stream by 3.4-fold (37.67 g/L). The permeate stream resulting from this first operation was subjected to a second NF-VSEP module (annular flat sheet composite polyamide membranes, 150 Da MWCO) to concentrate hydroxycinnamic acids, AX oligomers and RS. The permeate flux and retentate conductivity increased almost linearly as the VRF increased (1–5.5). At the end of the process (VRF 5.5), the concentrations of AX oligomers, hydroxycinnamic acids and RS in the retentate stream were greater than 3-fold than those in the initial feed. The resulting permeate stream was water with a minimal organic material content that can be reused in the process or disposed of in an environmentally friendly manner. The performance of the integrated pilot-scale NF-VSEP reveals a robust, efficient, and improved system to recover, separate and concentrate high biotechnology interest compounds from nejayote, overcoming serious limitations (fouling and fast permeate flux decline) present in static systems. The experimental data presented here set the standard for further industrial scaling to expand the value chain and guarantee the circular economy and global sustainability of the tortilla industry.

A Refined Closed-Form Solution for the Large Deflections of Alekseev-Type Annular Membranes Subjected to Uniformly Distributed Transverse Loads: Simultaneous Improvement of Out-of-Plane Equilibrium Equation and Geometric Equation

The Alekseev-type annular membranes here refer to annular membranes fixed at outer edges and connected with a movable, weightless, stiff, con-centric, circular thin plate at inner edges, which were proposed originally by Alekseev for bearing centrally concentrated loads. They are used to bear the pressure acting on both membranes and plates, which was proposed originally in our previous work for developing pressure sensors. The pressure is applied onto an Alekseev-type annular membrane, resulting in the parallel movement of the circular thin plate. Such a movement can be used to develop a capacitive pressure sensor using the circular thin plate as a movable electrode plate of a parallel plate capacitor. The pressure applied can be determined by measuring the change in capacitance of the parallel plate capacitor, based on the closed-form solution for the elastic behavior of Alekseev-type annular membranes. However, the previous closed-form solution is unsuitable for annular membranes with too large deflection, which limits the range of pressure operation of the developed sensors. A new and more refined closed-form solution is presented here by improving simultaneously the out-of-plane equilibrium equation and geometric equation, making it possible to develop capacitive pressure sensors with a wide range of pressure operations. The new closed-form solution is numerically discussed in its convergence and effectiveness and compared with the previous one. Additionally, its beneficial effect on developing the proposed capacitive pressure sensors is illustrated.

Revisiting the Boundary Value Problem for Uniformly Transversely Loaded Hollow Annular Membrane Structures: Improvement of the Out-of-Plane Equilibrium Equation

In a previous work by the same authors, a hollow annular membrane structure loaded transversely and uniformly was proposed, and its closed-form solution was presented; its anticipated use is for designing elastic shells of revolution. Since the height–span ratio of shells of revolution is generally desired to be as large as possible, to meet the need for high interior space, especially for the as-small-as-possible horizontal thrust at the base of shells of revolution, the closed-form solution should be able to cover annular membranes with a large deflection–outer radius ratio. However, the previously presented closed-form solution cannot meet such an ability requirement, because the previous out-of-plane equilibrium equation used the assumption of a small deflection–outer radius ratio. In this study, the out-of-plane equilibrium equation is re-established without the assumption of a small deflection–outer radius ratio, and a new and more refined closed-form solution is presented. The new closed-form solution is numerically discussed regarding its convergence and effectiveness, and compared with the old one. The new and old closed-form solutions agree quite closely for lightly loaded cases but diverge as the load intensifies. Differences in deflections, especially in stresses, are very significant when the deflection–outer radius ratio exceeds 1/4, indicating that, in this case, the new closed-form solution should be adopted in preference to the old one.

A rearrangement minimization problem corresponding top-Laplacian equation

In this paper a rearrangement minimization problem corresponding to solutions of thep-Laplacian equation is considered. The solution of the minimization problem determines the optimal way of exerting external forces on a membrane in order to have a minimum displacement. Geometrical and topological properties of the optimizer is derived and the analytical solution of the problem is obtained for circular and annular membranes. Then, we find nearly optimal solutions which are shown to be good approximations to the minimizer for specific ranges of the parameter values in the optimization problem. A robust and efficient numerical algorithm is developed based upon rearrangement techniques to derive the solution of the minimization problem for domains with different geometries in ℝ2and ℝ3.

Simulation of Design Parameters of a Milking Cup with An Extended Service Life

Abstract Modern milking machines need some additional studies to meet the requirements as to milking equipment. An imperfect design of a teatcup results in an incomplete milking of cows. The availability of devices for milk flow stimulation promotes an increase in a cow milk yielding capacity. But here arises a problem of an un-controlled axial motion of a teatcup on a teat. As a result, a full milkflow is reduced, particularly at the final stages of milking. There is an effect of an increase in an inner diameter of a liner barrel, which causes that teatcups fall down. A scientific problem of the mitigation of some negative developments with the view to improve the efficiency of a teatcup arises. In a teatcup shell a liner is in a detended position during milking and resting periods. Thus, it under constant stretching. It results in a loss of elasticity irrespective of the material, as well as in reduction ofthe period of service maintenance. The use of a device for supporting a liner which is in a stretched state only during the milkflow, will result in an increase of a teatcup efficiency. The suggested automatic pneumatic mechanism releases a liner from the load during the resting period. The dependence of a tension force of a liner from the surface area of an annular membrane has been established. It has been proven that the membrane surface of 0.00065 m2 provides tension for a mechanism performance irrespective of operating vacuum pressure. The regression equation which connects geometrical parameters of an operating system with the efforts directed at the opening of a leading membrane has been received. A suitability of operation of using a pneumatic tightening device has been substantiated. An insignificant axial motion of a liner during a cycle of milking creates a stimulating effect. As a result, a completeness of miliking increases by 3-8%.

Axisymmetric Large Deflection Elastic Analysis of Hollow Annular Membranes under Transverse Uniform Loading

The anticipated use of a hollow linearly elastic annular membrane for designing elastic shells has provided an impetus for this paper to investigate the large deflection geometrically nonlinear phenomena of such a hollow linearly elastic annular membrane under transverse uniform loads. The so-called hollow annular membranes differ from the traditional annular membranes available in the literature only in that the former has the inner edge attached to a movable but weightless rigid concentric circular ring while the latter has the inner edge attached to a movable but weightless rigid concentric circular plate. The hollow annular membranes remove the transverse uniform loads distributed on “circular plate” due to the use of “circular ring” and result in a reduction in elastic response. In this paper, the large deflection geometrically nonlinear problem of an initially flat, peripherally fixed, linearly elastic, transversely uniformly loaded hollow annular membrane is formulated, the problem formulated is solved by using power series method, and its closed-form solution is presented for the first time. The convergence and effectiveness of the closed-form solution presented are investigated numerically. A comparison between closed-form solutions for hollow and traditional annular membranes under the same conditions is conducted, to reveal the difference in elastic response, as well as the influence of different closed-form solutions on the anticipated use for designing elastic shells.

COMPARATIVE CHARACTERISTICS OF CHANGES IN HEMO - AND LYMPHOMICROCIRCULATORY VESSELS OF ILEUM ACCUMULATED LYMPHOID NODES OF RATS IN THE CASE OF APPLICATION OF INFUSION SOLUTIONS IN EXPERIMENTAL BURN DISEASE

Relevance. Thermal burns of the skin cause the development of burns, the main factor of which is endogenous intoxication. The infusion of detoxification solutions is a mandatory component of the treatment of burns, as it corrects its course and prevents the development of certain stages and complications. According to the stage of the burn disease and the different direction of its links in its pathogenesis, infusion therapy should not only restore water-electrolyte balance and detoxify the body, but also contribute to the normalization and stabilization of vital (including immune) body functions.
 Objective: study of changes in the vessels of the hemo- and lymphomicrocirculatory system of Peyer's patches in burnt rats at the stages of burn disease, under conditions of intravenous infusion of isotonic sodium chloride solution and combined colloidal-hyperosmolar solutions (lactoprotein and sorbitolum).
 Materials and methods. The experiment was performed on 72 white rats. Experimental animals were divided into 4 groups (18 animals in each group). I, II, III - rats with skin burn trauma, which received a separate infusion of isotonic sodium chloride (I), lactoprotein with sorbitol (II) and hecoton (III), at a dose of 10 ml / kg. IV - intact animals (control group).
 Simulation of burn disease was performed by inflicting burn injury by applying to the lateral surfaces of the body of animals four copper plates, which were previously kept for 6 minutes in water with a constant temperature of 100 ° C. Histological and electron microscopic examination were performed. Light microscopy was used.
 Results. Intravenous administration of the applied infusion solutions caused various phase changes of the hemo- and lymphomicrocirculatory tract of Peyer's patches of the ileum of burnt rats, depending on the applied solution. In the case of infusion of burnt rats with 0.9% sodium chloride solution, the negative effects of burn disease were exacerbated, which were manifested by damage to the vascular wall of the hemo- and lymphocapillary channels, resulting in plasma and lymph seepage through the affected areas into the perivascular space. This process was accompanied by a violation of the rheological properties of blood, the formation of edema. The established "membrane-plastic effect" of lactoprotein with sorbitol revealed clear organ-specific features, which had manifestations of penetration through the damaged wall of microvascular electron-dense impregnations, which contributed to a significant thickening of the basement membrane in the wall of the blood capillary formation and its gradual formation of rounded membranous structure. This structure of variable electron density not only strengthened the vascular wall, but also served as a closure, helping to close the vascular lumen at the site of largest damage. The difference between the perinodal lymphatic capillaries in burnt rats infused with lactoprotein and sorbitol is characterized by the phenomenon of "overflow" of the lymphocapillary channel with cells in different functional states. In the case of infusion of hecoton solution, the effect of "overflow" of the lymphocapillary channel was not observed, which indicates adequate implementation of the immune function of immunocompetent cells.
 Conclusions. Intravenous infusion of colloid-hyperosmolar solutions causes various changes in the hemo- and lymphomicrocirculatory tract of Peyer's patches. Infusion of a 0.9% sodium chloride solution leads to a deepening of the negative consequences of burn disease, which manifests itself in the form of damage to the vascular wall of the hemo- and lymphocapillary channels. Infusion of solutions of lactoprotein with sorbitol and hecoton helps to preserve the vascular wall of the nodular lymphatic capillaries. When a solution of lactoprotein with sorbitol is applied around the damaged vessels of blood capillaries and venules, annular membrane formations are formed, which promote selective recirculation of structurally intact lymphocytes.

Nonlinear problems of equilibrium for axisymmetric membranes

The problems for equilibrium of circular and annular membranes made of elastic-orthotropic and elastoplastic isotropic materials are considered in this paper in a geometrically and physically nonlinear formulation meeting the Föppl-Karman assumptions. The outer contour is considered to be stationary, while the inner one being free, or reinforced by either an elastic ring or a fixed disk. The load is assumed to be uniformly distributed over the membrane surface.The results of calculations of circular and annular membranes with large deflections in comparison with thickness, deformations and squares of angular displacement to be comparable with each other but small in comparison with the unit are presented in the first part thereof. The resulting boundary value problems are reduced to the Cauchy problem to be numerically integrated by the shooting method under the iterative Steffensen algorithm. For circular membrane structures an analytical solution as a power series similar to the Prescott series for a circular membrane is assumed either.The results of numerical solutions of problems are presented as dimensionless characteristic functions. Analysis of this information will enable to solve the problem of the support, being optimal in a certain sense when the membrane is close to be equal in strength.Problems of elastoplastic equilibrium of isotropic membranes are presented in the second part thereof. The idealized Prandtl diagram is used as the main characteristic of the mechanical properties of the membrane material. The Tresca-Sant-Venant and Huber-Mises-Hencky conditions were used as criteria for the transition of a material from an elastic state to a plastic one. Solutions of physically nonlinear equilibrium problems for axisymmetric membranes are also presented as dimensionless characteristic functions.

Modeling and analysis of a magnetoelastic annular membrane placed in an azimuthal magnetic field

This work presents the development of a 2D nonlinear magnetoelastic framework for a thin membrane undergoing large deformations. An asymptotic theory is obtained, starting from the 3D variational magnetostatic and force balance equations for a weakly magnetizable material. The model is subsequently specialized to axisymmetry and applied to a pre-stretched annular membrane deforming under azimuthal magnetic field and transverse pressure loading. Parametric studies are performed by varying the pre-stretch, magnetic field, and transverse pressure inputs.

Wrinkling analysis of circular membranes by a Fourier based reduced model

As a material with an almost negligible bending stiffness, membranes may easily lose their mechanical stability. Generally, the wave lengths of the wrinkles are quite small, leading to the intensive computation in numerical simulations. To deal with the issue, a Fourier based reduced model is recently developed by Huang et al. (2019) showing good performance in both accuracy and efficiency for the simulation of circular membrane wrinkling. The objective of this paper is to improve the reduced model by accounting for several Fourier harmonics, then employ it to study the wrinkling phenomenon in the circular domain. By accounting for several Fourier harmonics, the reduced model can automatically distinguish the lowest instability pattern, which facilitates the study of the cases of unknown wrinkling patterns. The instability mechanism of an annular membrane under in-plane stretching is also investigated. The results show that the appearance of the wrinkles in circular membranes does not rely on the Poisson’s effect, although the value of Poisson’s ratio and the geometric dimensions have great influence on the wrinkling patterns. Finally, the instability problem of a circular thin plate under the in-plane compression is studied. The effects of the boundary condition and the wrinkling pattern on the crest position and the critical load are investigated.

Coulomb split evolution behavior in different growth stages of droplets

The dynamic behavior of droplets under the electric field has attracted extensive research interests due to its widespread industrial applications, such as emulsification, transesterification and drug delivery. In this study, we investigated experimentally the novel Coulomb splitting behavior of charged droplets at different growth stages in the surrounding fluid when exposed to an electric field. Besides, we accurately captured the microscopic features of charged droplets and the evolutionary details of the Coulomb splitting process under different electric field strengths. The force analysis of the droplets attached to the nozzle under the electric field was carried out. The new phenomena of expansion-contraction deformation, bifurcation breakup, and annular membrane oscillation behavior of droplets were obtained successfully by manipulating the electric field. It is noted that in the initial growth stage, the droplet deformation and breakup degree are relatively large. Under high electric field strength, the surface area of the formed liquid film is about nine times the surface area before droplet crushing. It is found that the pressure difference formed inside and outside the liquid film could promote the backflow phenomenon of shattered small droplets. Furthermore, three regimes of Coulomb splitting were distinguished with the change of electric bond number BoE in the overall phase diagram.

Fully Flexible Electromagnetic Vibration Sensors with Annular Field Confinement Origami Magnetic Membranes

AbstractSensing of mechanical motion based on flexible electromagnetic sensors is challenging due to the complexity of obtaining flexible magnetic membranes with confined and enhanced magnetic fields. A fully flexible electromechanical system (MEMS) sensor is developed to conduct wearable monitoring of mechanical displacement with excellent adaptability to complex surface morphology through a suspended flexible magnet enclosed within a novel setup formed by a multi‐layer flexible coil and annular origami magnetic membranes. The annular membranes not only regulate the overall distribution of the magnetic field and enhance the overall magnetism by 291%, but also greatly increase the range of the magnetic field to cover the entire region of the coil. The sensor offers a broad frequency response ranging from 1 Hz to 10 kHz and a sensitivity of 0.59 mV µm−1 at 1.7 kHz. The fully flexible format of the sensor enables various applications demonstrated by biophysical sensing, motion detection, voice recognition, and machine diagnostics through direct attachment on soft and curvilinear surfaces. Similar sensors can combine multiple sensing and energy harvesting modalities to achieve battery‐less and self‐sustainable operation, and can be deployed in large numbers to conduct distributed sensing for machine status assessment, health monitoring, rehabilitation, and speech aid.

A Closed-Form Solution of Prestressed Annular Membrane Internally-Connected with Rigid Circular Plate and Transversely-Loaded by Central Shaft

In this paper, we analytically dealt with the usually so-called prestressed annular membrane problem, that is, the problem of axisymmetric deformation of the annular membrane with an initial in-plane tensile stress, in which the prestressed annular membrane is peripherally fixed, internally connected with a rigid circular plate, and loaded by a shaft at the center of this rigid circular plate. The prestress effect, that is, the influence of the initial stress in the undeformed membrane on the axisymmetric deformation of the membrane, was taken into account in this study by establishing the boundary condition with initial stress, while in the existing work by establishing the physical equation with initial stress. By creating an integral expression of elementary function, the governing equation of a second-order differential equation was reduced to a first-order differential equation with an undetermined integral constant. According to the three preconditions that the undetermined integral constant is less than, equal to, or greater than zero, the resulting first-order differential equation was further divided into three cases to solve, such that each case can be solved by creating a new integral expression of elementary function. Finally, a characteristic equation for determining the three preconditions was deduced in order to make the three preconditions correspond to the situation in practice. The solution presented here could be called the extended annular membrane solution since it can be regressed into the classic annular membrane solution when the initial stress is equal to zero.

Biophysical characterization of a series of novel non‐RAFT copolymers with improved buffer behavior

Synthetic amphipathic polymers present an invaluable tool for excision and liberation of superstructures of membrane proteins (MPs) and their surrounding annular membrane bilayer in donut‐shaped nanoparticles or discs. Styrene‐co‐maleic acid polymers (SMAs) have demonstrated most efficiency for the structural characterization of membrane proteins. However, some drawbacks such as sensitivity to acidic pH and high concentration of divalent cations, interference with the spectroscopic profiles of proteins, high polydispersity index (PDI) and nonspecific interaction with protein surface have hindered the ultimate optimal utilization of SMA polymers for functional characterization of MPs in lipid bilayer and hence for drug discovery purposes. We have developed multiple series of novel non‐RAFT amphipathic polymers that demonstrate improved behaviors in acidic pH and high concentration of calcium. Some of these unique amphipathic polymers display exemplary polydispersity (PDI ~1), strict alternation (a well‐defined sequence of comonomers) and distinct spectrophotometric profiles. We further characterized the application of these novel polymeric detergents for purification of a model integral beta‐barrel MP, PagP, from the outer membrane of E. coli.

Deactivation-induced dynamics of the reaction front in a fixed-bed catalytic membrane reactor: Methane cracking as a case study

Thermo-Catalytic decomposition (TCD) of methane can be regarded as a cornerstone towards the development of greenhouse gas-free processes for pure hydrogen production. Most studies of TCD focused on process schemes where the extraction of hydrogen from the gaseous CH4−H2 mixture is accomplished in a unit separated from the reaction environment. In this article, we investigate numerically a different setup that involves the use of a semi-batch annular fixed-bed membrane reactor. The permeselective membrane allows to lower the reaction temperature, overcoming equilibrium limitations. The intrinsic time-dependency of the process (induced by catalyst deactivation due to massive deposition of the solid carbon product), together with spatial concentration gradients triggered by hydrogen permeation through the membrane give rise to a non-trivial dynamical behavior of the reactor. Specifically, we observe that a localized reaction front develops near the membrane at the early stage of the process. At later times, the front moves away from the membrane zone throughout the bed as larger and larger portions of the catalyst become inactive. The front thickness and dynamics are found to have a strong influence upon the overall timescales of the reaction. A dimensionless analysis of the dependence of the reactor efficiency on the pressure and on the catalyst activity (here quantified by the Damköhler number) is carried out by assuming 550 °C as a working temperature. An optimal working pressure is found at relatively high Damköhler value. Qualitatively different operating modes of the membrane reactor in different regions of the pressure-Damköhler parameter space are identified and interpreted.