Rigidity and transient wave dynamics of random networks
Authors
Date
1998This thesis work deals with two major topics: the rigidity of random line networks and transient wave-front propagation in random discrete media. Rigidity means the ability of a mechanical system to store elastic energy when it is deformed. Random line networks composed of springs are found to be nonrigid at their basic configuration. This is confirmed both by a relaxation method and by a topological algorithm. These networks are found to become rigid at large strains for which the nonlinear stress-strain behaviour is analysed. A reinforced random line network is found to have a transition between rigid and nonrigid phases. The numerical evidence does not support a pure second-order phase transition. The velocity and amplitude of the leading front of elastic waves propagating in various one- and two-dimensional networks are studied. The leading front is defined in this work as the first displacement maxima of the points initially at rest in the network. In perfect lattices the amplitude first oscillates and then decays following a power law. With increasing disorder the early-time behaviour of the front changes to an exponential decay. The decay coefficient is a universal power-law as a function of the dilution parameter. Two limits of wave-front propagation dynamics are found. If the longitudinal and transverse velocities are equal, disorder is small, and wavelengths are large, the effective-medium approximation correctly estimates the wave-front behaviour. Conversely, if the two modes have different velocities, the system is more disordered, and the wavelengths are small, the propagation of the leading front takes place along effectively one-dimensional paths of propagation. In this limit the amplitude usually decays faster and the velocity is higher than in the effective-medium limit. Roughening of the leading wave front is analysed in both elastic percolation lattices and TLM lattices. Roughening means increase of the width of an interface as a function of time and the scale of observation. The kinetics of the roughening of the leading front is found to be partly described by a scaling argument based on Huygens' principle. Finally, conclusions of the results of this thesis are drawn and their implications discussed.
...
ISBN
978-951-39-9453-2ISSN Search the Publication Forum
0075-465XContains publications
- Artikkeli I: Kellomäki, M., Åström, J. and Timonen, J. (1996). Rigidity and Dynamics of Random Spring Networks. Physical Review Letters, 77, 2730. DOI: 10.1103/PhysRevLett.77.2730
- Artikkeli II: Åström, J., Kellomäki, M. and Timonen, J. (1997). Elastic waves in random-fibre networks. Journal of Physics A: Mathematical and General, 30(19). DOI: 10.1088/0305-4470/30/19/004
- Artikkeli III: Åström, J., Kellomäki, M., Alava, M. and Timonen, J. (1997). Propagation and kinetic roughening of wave fronts in disordered lattices. Physical Review E, 56, 6042. DOI: 10.1103/PhysRevE.56.6042
- Artikkeli IV: Kellomäki, M., Åström, J. and Timonen, J. (1998). Early-time dynamics of wave fronts in disordered triangular lattices. Physical Review E, 57, R1255(R). DOI: 10.1103/PhysRevE.57.R1255
- Artikkeli V: Kellomäki, M., Åström, J. and Timonen, J. Elastic-wave fronts in one- and two-dimensional random media. Submitted.
Metadata
Show full item recordCollections
- Väitöskirjat [3589]
License
Related items
Showing items with similar title or keywords.
-
Transient seizure onset network for localization of epileptogenic zone : effective connectivity and graph theory-based analyses of ECoG data in temporal lobe epilepsy
Ren, Ye; Cong, Fengyu; Ristaniemi, Tapani; Wang, Yuping; Li, Xiaoli; Zhang, Ruihua (Springer Berlin Heidelberg, 2019)Objective: Abnormal and dynamic epileptogenic networks cause difficulties for clinical epileptologists in the localization of the seizure onset zone (SOZ) and the epileptogenic zone (EZ) in preoperative assessments of ... -
An Efficient Network Log Anomaly Detection System using Random Projection Dimensionality Reduction
Juvonen, Antti; Hämäläinen, Timo (IEEE, 2014)Network traffic is increasing all the time and network services are becoming more complex and vulnerable. To protect these networks, intrusion detection systems are used. Signature-based intrusion detection cannot find ... -
A randomized controlled trial for response of microbiome network to exercise and diet intervention in patients with nonalcoholic fatty liver disease
Cheng, Runtan; Wang, Lu; Le, Shenglong; Yang, Yifan; Zhao, Can; Zhang, Xiangqi; Yang, Xin; Xu, Ting; Xu, Leiting; Wiklund, Petri; Ge, Jun; Lu, Dajiang; Zhang, Chenhong; Chen, Luonan; Cheng, Sulin (Nature Publishing Group, 2022)Exercise and diet are treatments for nonalcoholic fatty liver disease (NAFLD) and prediabetes, however, how exercise and diet interventions impact gut microbiota in patients is incompletely understood. We previously reported ... -
Contact formation in random networks of elongated objects
Ekman, Axel; Miettinen, Arttu; Tallinen, Tuomas; Timonen, Jussi (American Physical Society, 2014)The effect of steric hindrance is an important aspect of granular packings as it gives rise to, e.g., limitations on the densities of ordered and disordered packings, both of which are essentially defined by the geometry ... -
Elasticity and stiffness evolution in random fibre networks
Kähkönen, Sami (University of Jyväskylä, 2003)