A hybrid finite-element material-point approach for anchored tunnels in large deformation

Bridging mesostructure features and mechanical integrity of graphite anode coating under large deformation: Mesoscale modeling and parametric study

Soft bioelectronic skins represent next-generation wearable technologies for continuous and unobtrusive biomonitoring, enabled by diverse active materials and topological designs. Despite encouraging progress, most wearable skins reported to date remain unable to match the abrasion-resistant sensing functions of human skin. Here, we present abrasion-resistant wearable skins based on a bilayer stretchable conductor architecture. The top layer, composed of silver particle (AgPs)-impregnated styrene-ethylene-butylene-styrene (SEBS), provides superior abrasion resistance, while the underlying layer of liquid metal particle (LMPs)-impregnated SEBS ensures high conductivity under large strains (ε > 900%). While being ultrathin (13.3 µm), the bilayer wearable skins could deliver exceptional durability under extreme mechanical and chemical demands, maintaining electromechanical stability during repeated abrasion, large deformations, and exposure to strong acidic/alkaline environments. They reliably capture high-fidelity mechanical and electrophysiological signals in abrasion-intensive scenarios, such as skin-cloth friction and facial rubbing. Finally, we demonstrate a soft, multimodal system for pressure and biopotential monitoring, enabling applications in braille recognition and facial expression detection with 98.75% prediction accuracy.

Complex and robust tissue self-organization requires defined initial conditions and dynamic boundaries-neighbouring tissues and extracellular matrix that actively evolve to guide morphogenesis. A major challenge in tissue engineering is identifying material properties that are compatible with controlling initial culture conditions while mimicking dynamic tissue boundaries. Here we describe a highly tunable granular biomaterial, MAGIC matrix, that supports both long-term bioprinting and gold-standard tissue self-organization. We identify that significant stress relaxation at the long timescales and large deformation magnitudes relevant to self-organization is required for optimal morphogenesis. We apply optimized MAGIC matrices toward precise extrusion bioprinting of saturated cell suspensions directly into three-dimensional culture. Carefully controlling initial conditions for tissue growth yields dramatic increases in organoid reproducibility and complexity across multiple tissue types, enabling high-throughput generation of organoid arrays and perfusable three-dimensional microphysiological systems. Our results identify key biomaterial parameters for optimal organoid morphogenesis and lay the foundation for fabricating more complex and reproducible self-organized tissues.

Abstract Background Mechanical testing of soft materials requires specialized equipment. Unfortunately, commercial devices are expensive and, thus, prohibitive for many laboratories. Additionally, non-uniformity in device use across laboratories contributes to the reproducibility crisis in experimental mechanics. Finally, even expensive commercial devices are usually not adaptable and do not allow for customization, for example, to integrate in-situ imaging modalities into the test protocols. Objective Therefore, our objective was to develop a device that is accessible, customizable, and compatible with various imaging modalities. Methods We set out to develop a device capable of operating in biaxial, off-biaxial, and uniaxial modes under monotonic loading, cyclic testing, and stress relaxation. To this end, we combined a 3D printed device platform with off-the-shelf motors, load cells, and LabVIEW control. Results Our device is easy to use, relatively inexpensive ( $$\approx $$ ≈ $15,000), and fully customizable. To showcase the device, we first obtained equibiaxial stress-strain curves of rubber samples under large deformation. Additionally, we tracked in-plane strains via digital image correlation and through-thickness deformations via optical coherence tomography. In our second and third examples, we produced strip biaxial and biaxial stress-strain curves under repeated step and stress relaxation loading of PCL meshes and a tricuspid valve leaflet, respectively. Simultaneously, we imaged the microstructure of the materials via confocal and multiphoton microscopy. Conclusion In conclusion, we have designed a device that is accessible, customizable, and compatible with various imaging modalities. We hope that our technology enables other labs to conduct soft material tests and that it improves the reproducibility of soft material mechanical data.

Progressive collapse of reinforced concrete frames considering large deformation effects

Living systems operate far from thermodynamic equilibrium. Movements in cells are always driven by thermal forces but, more importantly, also by motor-generated active forces in the cytoplasm. How intracellular structures respond to these forces depends on their mechanical properties. Intracellular dynamics remain challenging to understand because, in most cases, neither local forces nor local material response properties are known, and imaging of fluctuations is typically not sufficient to measure both. While some subcellular structures such as actin filaments and microtubules, which form the major cytoskeletal networks, have been extensively studied , their mechanical properties in living cells where they are regulated by post-translational modifications and association with regulatory factors remain poorly understood. Here we present an alternative approach that uses nonequilibrium bending fluctuations of rod-shaped structures to characterize their mechanical properties and those of their surroundings and to estimate driving forces. We demonstrate that, when one of the three factors—two material properties and one driving force—is determined independently, the other two can be derived from observed fluctuations. By applying our method to microtubules in living cells we find that polyglutamylation, a post-translational modification enriched on microtubules that need to withstand large deformation forces like those in axons or cilia, increases microtubule stiffness. In contrast, tubelike mitochondria, lipid membrane-bounded organelles which easily deform, yielded a bending stiffness significantly lower than that of microtubules. Our method opens the door to a quantitative understanding of the effects of cellular factors on the mechanical properties of filaments and organelles in cells.

Buried oil and gas pipelines, the critical arteries of global energy infrastructure, are increasingly vulnerable to severe geological hazards such as reverse faulting, yet their structural integrity is often pre-compromised by stochastic corrosion damage accumulated during service. However, quantifying the coupled impact of spatial corrosion heterogeneity and large ground deformation remains a formidable challenge due to the complex nonlinearities involved in soil-structure interactions and wall thinning. This study establishes a probabilistic assessment framework integrating random field theory, nonlinear finite element analysis, and a generative conditional diffusion model to characterize realistic 2D non-Gaussian corrosion morphologies. The numerical results reveal a significant geometric stiffening effect induced by internal pressure, where moderate operating levels effectively suppress cross-sectional distortion by counteracting the Brazier effect. Consequently, this mechanism facilitates a fundamental transition in failure modes from localized tensile rupture to ductile buckling, significantly extending the critical fault displacement threshold. Furthermore, probabilistic fragility analysis demonstrates that the spatial dispersion of pitting, rather than just average wall thinning, governs the initiation of premature failure. Mechanistic analysis indicates that high internal pressure, while providing pneumatic support, exacerbates tensile strain localization at corrosion pits, leading to a heightened probability of premature rupture under minor fault deformations, a critical hazard that traditional deterministic models significantly underestimate. These findings provide a quantitative theoretical foundation for the reliability-based design and maintenance of energy lifelines traversing active tectonic zones.

Characterization of anisotropic nonlinear material properties along with fiber directions for soft tissues based on known deformations (strains) and external loads is a significant clinical goal. A gradient-based inverse solver is developed to retrieve anisotropic nonlinear tissue properties. By directly minimizing nodal force residuals using known deformed and reference configurations, the method avoids repeated forward simulations. To represent complex, non-trivial spatial distributions, the material properties are parameterized using a multilayer perceptron (MLP) that maps spatial location to material behavior, in contrast to methods that use such networks to approximate the displacement field itself. For faster convergence, residual smoothing is performed, and the Jacobian computation is parallelized. The framework supports general constitutive laws as demonstrated by Neo-Hookean and Fung-type models. The inverse solver is verified for a variety of cases, including spatially varying elasticity and anisotropic fiber distributions, and its applicability to complex 3D geometries is demonstrated on a bioprosthetic heart valve. The residual-only formulation leads to faster optimization iterations compared to Physics-Informed Neural Network (PINN) approaches, which involve computationally expensive updates to a displacement-approximating network. Unlike the Neo-Hookean constitutive model, the Fung model, especially with element-wise recovery of parameters, exhibits nonuniqueness, where different spatial distributions of parameters can yield similar residual levels; in contrast, fiber direction recovery remains robust across all cases. The inverse solver is capable of recovering nonlinear material properties and fiber directions even for complex 3D problems with large deformations such as heart valves.

Large deformations in deep soft rock roadways primarily stem from low rock strength under high in situ stress and intense mining disturbance. This renders stability control a critical challenge in tunneling support engineering. Utilizing Xinhe Coal Mine’s deep soft rock tunnel as a representative case, this study integrates field monitoring, laboratory experimentation, and numerical simulation to investigate how excavation and grouted rock bolting influence surrounding rock stability. Building upon field-observed deformation mechanisms and support failure patterns, constitutive models for FLAC3D’s embedded cable and beam elements were modified to achieve high-fidelity simulation of grouted support systems. Numerical models simulating diverse support schemes were established to analyze roadway displacement fields, plastic failure development, and structural behavior of support components, ultimately identifying the optimal rehabilitation solution. The research results indicate that the numerical simulation outcomes of the original support scheme exhibit good agreement with field observations in terms of roadway deformation patterns, deformation magnitudes, and occurrences of bolt/cable fractures. This demonstrates that the adopted refined numerical simulation methodology and parameters are reasonable and exhibit high reliability. Considering both surrounding rock stability and cost control, Roadway Rehabilitation Scheme S1 was identified as the optimal support solution. Its specific parameters are pre-grouting + full-section rock bolts (diameter 22 mm, length 2.4 m, spacing 0.8 m, row spacing 1.6 m) + full-section grouted cables (diameter 22 mm, length 6.2 m, spacing 1.0 m, row spacing 1.6 m).

Flax Fiber Reinforced Polymer (FFRP), as a green material with nonlinear large deformation characteristics, is used in the reinforcement of timber structures. Due to the similar elastic moduli of FFRP, adhesive, and timber, stress concentration at the interface is significantly reduced, demonstrating favorable interfacial performance. This study investigates the effects of adhesive layer thickness and FFRP laminate thickness on the strain distribution, bond-slip relationship, and stress distribution at the FFRP-timber interface through two different types of single-lap shear tests, thereby revealing the bonding mechanism at the FFRP-timber interface. The results show that both the ultimate load and the ultimate strain at the loaded end decrease with increasing adhesive thickness. For instance, increasing the adhesive thickness from 0.5 mm to 3 mm led to a 68.6% reduction in peak interfacial shear stress. The thickness of the adhesive has a minor influence on the overall trend of the bond-slip relationship curve for the FFRP-timber interface, with the curve consisting of an ascending branch, a descending branch, and a horizontal plateau. The distribution patterns of interfacial shear stress for different adhesive layer thicknesses are similar: at the initial loading stage, the maximum shear stress appears at the loaded end and gradually decreases toward the free end; as the load increases, the peak shear stress shifts from the loaded end toward the free end. With an increase in the number of fiber layers in the FFRP laminate, the strain transfer efficiency first increases and then decreases, reaching its maximum when the number of fiber layers reaches 30. The maximum stress increases with the number of FFRP fiber layers, and the stress transfer efficiency peaks at 30 layers.

Highly deformable adhesive materials are increasingly employed in engineering applications where flexibility, energy dissipation and damage tolerance are required. The mechanical characterisation of these materials, however, presents significant challenges due to their pronounced non-linear behaviour, large deformations, and, in many cases, time-dependent effects. This paper provides a critical review of experimental, constitutive and numerical approaches used for the characterisation of highly deformable adhesive materials, considered here as bulk materials independently of a specific joint configuration. The review covers mechanical testing methods under large strains, hyperelastic and visco-hyperelastic constitutive models, and the application of fracture mechanics concepts and numerical techniques as exploratory tools for material analysis and comparison. Particular attention is given to the capabilities and limitations of the different approaches, their domains of applicability and the assumptions involved in their use. By highlighting current practices, open challenges and recent developments, this work aims to support the selection of appropriate characterisation methodologies and modelling strategies for highly deformable adhesive materials.

A globally discretized ALE beam model for cable-driven parallel robots with large deformations

Large rock slope deformations: Evidence of orogen-scale distribution from an original inventory in central Apennines (Italy)

Robust sequential pixel offset tracking (RS-POT): A novel monitoring approach for landslides with long-term large deformations

Performance verification of a dual-range stretchable vertical graphene strain sensor for microstrain and large deformation monitoring

Study and application of energy-dissipating yielding support for large deformation in hard rock tunnel subjected to extremely high geostress

GeoDualSPHysics: a high-performance SPH solver for large deformation modelling of geomaterials with two-way coupling to multi-body systems

Progress in constitutive modeling of arterial wall tissue mechanics: from theoretical frameworks to clinical application.

A case study of failure mechanisms and NPR cable-based support strategies for asymmetric large deformation in deep-buried soft rock tunnels crossing faults