Dennis M. Kochmann


Last Name

Kochmann

First Name

Dennis M.

ORCID

0000-0002-9112-6615

Organisational unit

09600 - Kochmann, Dennis / Kochmann, Dennis

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Publications 1 - 10 of 144
  • A conforming frictional beam contact model
    Item type: Journal Article
    Karapiperis, Konstantinos; Widmer, Adrian; Pescialli, Elias; et al. (2024)
    Computer Methods in Applied Mechanics and Engineering
    We develop a model for predicting the mechanical behavior of a system of slender one-dimensional bodies (fibers or beams) interacting via frictional contact. Relying on an integral penalty-based formulation, it can robustly capture the behavior in the case of conforming contact occurring over regions of finite size. Two formulations of the model are presented and validated against fully resolved continuum finite element simulations. Overall, the proposed framework is an effective tool in exploring the mechanical behavior of fabrics, textiles as well as three-dimensional frictional architected solids, as demonstrated by the simulation of the effective response of a periodic intertwined metamaterial.
  • Damage-induced mechanical damping in phase-transforming composites materials
    Item type: Journal Article
    Junker, Philipp; Kochmann, Dennis M. (2017)
    International Journal of Solids and Structures
  • Topology-Informed Design of Intertwined Architected Materials: Unifying Woven, Knotted, and Closed-Chain Networks
    Item type: Journal Article
    Pescialli, Elias; Muñoz López, Adrià; Karapiperis, Konstantinos; et al. (2025)
    Materials & Design
    The design of architected materials with intertwined networks represents a promising avenue for creating structures with unique and programmable mechanical properties. However, a systematic, quantitative framework for prescribing and controlling the underlying fiber topology has remained elusive. This paper introduces a hierarchical computational framework that addresses this challenge by enabling the topology-informed design of intertwined helix-based architected materials and structures. The methodology progresses from an abstract, graph-based representation of port-level connectivity to the precise geometric realization of complex strand-level topologies with prescribed entanglement. We demonstrate the framework's versatility by generating a wide array of intertwined networks, bridging woven, knotted, and closed-chain topologies, all unified under a single design paradigm. In addition, we present topological metrics that quantitatively capture the intertwining relationships among fibers—providing a valuable tool to map the prescribed design parameters and the resulting structural characteristics. Through a case study of a cubic lattice, we illustrate how the choice of port-level connectivity dictates material allocation and anisotropy, while the strand-level realization provides combinatorial freedom for tailoring specific entanglement patterns. This work establishes the foundation for designing intertwined architected materials, enabling control over topological invariants and providing a tool for exploring the influence of topology on material performance.
  • Multiphysics modeling of hydrogels with a maximum-entropy-based meshless framework
    Item type: Journal Article
    Castillo-Acuna, Rodrigo; Kochmann, Dennis M. (2025)
    Computer Methods in Applied Mechanics and Engineering
    Hydrogels are soft, stimuli-responsive materials with attractive applications from soft robotics to biomedical engineering. Their multiphysics nature combined with their ability to undergo large deformation and mechanical instability makes their computational modeling challenging. As a potential remedy, we here introduce a meshless multiphysics framework based on enhanced local maximum-entropy (max-ent) interpolants. This formulation, tailored for hydrogel simulations, leverages the flexibility of the meshless max-ent scheme (without the need to remesh up to large deformation and significant distortion), the robustness of the enhanced local max-ent interpolants, and the physio-mechanically coupled monophasic continuum theory of hydrogels (combining a transient Fickian-type diffusion model with quasistatic finite-strain mechanics). The effectiveness of our approach is verified through a series of benchmark tests, including the free swelling of different hydrogel sample geometries in 3D and the deformation of complex 2D and 3D hollow hydrogel structures. Our results demonstrate that the proposed framework maintains stability up to large deformation and large distortions of the initial geometry, thus making it a promising tool for hydrogel simulations, particularly in applications involving complex geometries made possible by recent advances in hydrogel manufacturing, such as 3D printing.
  • Numerical Approaches for Investigating Quasiconvexity in the Context of Morrey's Conjecture
    Item type: Journal Article
    Voss, Jendrik; Martin, Robert J.; Sander, Oliver; et al. (2022)
    Journal of Nonlinear Science
  • Soft Adaptive Mechanical Metamaterials
    Item type: Journal Article
    Khajehtourian, Romik; Kochmann, Dennis M. (2021)
    Frontiers in Robotics and AI
    Soft materials are inherently flexible and make suitable candidates for soft robots intended for specific tasks that would otherwise not be achievable (e.g., smart grips capable of picking up objects without prior knowledge of their stiffness). Moreover, soft robots exploit the mechanics of their fundamental building blocks and aim to provide targeted functionality without the use of electronics or wiring. Despite recent progress, locomotion in soft robotics applications has remained a relatively young field with open challenges yet to overcome. Justly, harnessing structural instabilities and utilizing bistable actuators have gained importance as a solution. This report focuses on substrate-free reconfigurable structures composed of multistable unit cells with a nonconvex strain energy potential, which can exhibit structural transitions and produce strongly nonlinear transition waves. The energy released during the transition, if sufficient, balances the dissipation and kinetic energy of the system and forms a wave front that travels through the structure to effect its permanent or reversible reconfiguration. We exploit a triangular unit cell’s design space and provide general guidelines for unit cell selection. Using a continuum description, we predict and map the resulting structure’s behavior for various geometric and material properties. The structural motion created by these strongly nonlinear metamaterials has potential applications in propulsion in soft robotics, morphing surfaces, reconfigurable devices, mechanical logic, and controlled energy absorption.
  • Guided transition waves in multistable mechanical metamaterials
    Item type: Journal Article
    Jin, Lishuai; Khajehtourian, Romik; Müller, Jochen; et al. (2020)
    Proceedings of the National Academy of Sciences of the United States of America
  • Preface of the guest‐editors
    Item type: Other Journal Item
    Kochmann, Dennis M.; Linder, Christian (2015)
    GAMM-Mitteilungen
  • Nonequilibrium thermomechanics of Gaussian phase packet crystals: Application to the quasistatic quasicontinuum method
    Item type: Journal Article
    Gupta, Prateek; Ortiz, Michael; Kochmann, Dennis M. (2021)
    Journal of the Mechanics and Physics of Solids
    The quasicontinuum (QC) method was originally introduced to bridge across length scales by coarse-graining an atomistic ensemble to significantly larger continuum scales at zero temperature, thus overcoming the crucial length-scale limitation of classical atomic-scale simulation techniques while solely relying on atomic-scale input (in the form of interatomic potentials). An associated challenge lies in bridging across time scales to overcome the time-scale limitations of atomistics at finite temperature. To address the biggest challenge, bridging across both length and time scales, only a few techniques exist, and most of those are limited to conditions of constant temperature. Here, we present a new general strategy for the space–time coarsening of an atomistic ensemble, which introduces thermomechanical coupling. Specifically, we evolve the statistics of an atomistic ensemble in phase space over time by applying the Liouville equation to an approximation of the ensemble’s probability distribution (which further admits a variational formulation). To this end, we approximate a crystalline solid as a lattice of lumped correlated Gaussian phase packets occupying atomic lattice sites, and we investigate the resulting quasistatics and dynamics of the system. By definition, phase packets account for the dynamics of crystalline lattices at finite temperature through the statistical variances of atomic momenta and positions. We show that momentum-space correlation allows for an exchange between potential and kinetic contributions to the crystal’s Hamiltonian. Consequently, local adiabatic heating due to atomic site motion is captured. Moreover, in the quasistatic limit, the governing equations reduce to the minimization of thermodynamic potentials (similar to maximum-entropy formulation previously introduced for finite-temperature QC), and they yield the local equation of state, which we derive for isothermal, isobaric, and isentropic conditions. Since our formulation without interatomic correlations precludes irreversible heat transport, we demonstrate its combination with thermal transport models to describe realistic atomic-level processes, and we discuss opportunities for capturing atomic-level thermal transport by including interatomic correlations in the Gaussian phase packet formulation. Overall, our Gaussian phase packet approach offers a promising avenue for finite-temperature non-equilibrium quasicontinuum techniques, which may be combined with thermal transport models and extended to other approximations of the probability distribution as well as to exploit the variational structure.
Publications 1 - 10 of 144