COUPLING MATTER AGGLOMERATION WITH MECHANICAL STRESS RELAXATION AS A WAY OF MODELING THE FORMATION OF JAMMED MATERIALS Adam Gadomski Institute of Mathematics and Physics University of Technology and Agriculture Bydgoszcz, Poland XIX SITGES CONFERENCE JAMMING, YIELDING, AND IRREVERSIBLE DEFORMATION June, 2004, Universitat de Barcelona, Sitges, Catalunya

OBJECTIVE: TO COUPLE, ON A CLUSTER MESOSCOPIC LEVEL & IN A PHENOMENOLOGICAL WAY, ADVANCED STAGES OF CLUSTER-CLUSTER AGGREGATION WITH STRESS-STRAIN FIELDS XIX SITGES CONFERENCE JAMMING,YIELDING, AND IRREVERSIBLE DEFORMATION

THE PHENOMENOLOGY BASED UPON A HALL-PETCH LIKE RELATIONSHIP CONJECTURE FOR CLUSTER-CLUSTER LATE-TIME AGGREGATION XIX SITGES CONFERENCE JAMMING,YIELDING, AND IRREVERSIBLE DEFORMATION - internal stress accumulated in the inter-cluster spaces -average cluster radius, to be inferred from the growth model; a possible extension, with a q, like

TWO-PHASE SYSTEM Model cluster- cluster aggregation of one-phase molecules, forming a cluster, in a second phase (solution): (A) An early growing stage – some single cluster (with a double layer) is formed; (B) A later growing stage – many more clusters are formed XIX SITGES CONFERENCE JAMMING,YIELDING, AND IRREVERSIBLE DEFORMATION

Dense Merging (left) vs Undense Merging (right) (see, Meakin & Skjeltorp, Adv. Phys. 42, 1 (1993), for colloids) TYPICAL CLUSTER-MERGING (3 GRAINS) MECHANISMS: XIX SITGES CONFERENCE JAMMING,YIELDING, AND IRREVERSIBLE DEFORMATION

RESULTING 2D-MICROSTRUCTURE IN TERMS OF DIRICHLET-VORONOI MOSAIC REPRESENTATION (for model colloids – Earnshow & Robinson, PRL 72, 3682 (1994)) XIX SITGES CONFERENCE JAMMING,YIELDING, AND IRREVERSIBLE DEFORMATION INITIAL STRUCTUREFINAL STRUCTURE

XIX SITGES CONFERENCE JAMMING,YIELDING, AND IRREVERSIBLE DEFORMATION „Two-grain” model: a merger between growth&relaxation „Two-grain” spring-and- dashpot Maxwell- like model with (un)tight piston: a quasi-fractional viscoelastic element

THE GROWTH MODEL COMES FROM MNET (Mesoscopic Nonequilibrium Thermodynamics, Vilar & Rubi, PNAS 98, (2001)): a flux of matter specified in the space of cluster sizes XIX SITGES CONFERENCE JAMMING,YIELDING, AND IRREVERSIBLE DEFORMATION - hypervolume of a single cluster (internal variable) -independent parameters <-Note: cluster surface is crucial! drift term diffusion term surface - to - volume characteristic exponent scaling: holds !

GIBBS EQUATION OF ENTROPY VARIATION AND THE FORM OF DERIVED POTENTIALS AS ‘STARTING FUNDAMENTALS’ OF CLUSTER-CLUSTER LATE-TIME AGGREGATION XIX SITGES CONFERENCE JAMMING,YIELDING, AND IRREVERSIBLE DEFORMATION -internal variable and time dependent chemical potential -denotes variations of entropy S and (i) Potential for dense micro-aggregation (another one for nano-aggregation is picked up too): (ii) Potential for undense micro-aggregation:

Local conservation law: IBCs (IC usually of minor importanmce): a typical BCs prescribed XIX SITGES CONFERENCE JAMMING,YIELDING, AND IRREVERSIBLE DEFORMATION additional sources = zero divergence operator Local conservation law and IBCs

AFTER SOLVING THE STATISTICAL PROBLEM IS OBTAINED USEFULL PHYSICAL QUANTITIES: TAKEN MOST FREQUENTLY (see, discussion in: A. Gadomski et al. Physica A 325, 284 (2003)) FOR THE MODELING where XIX SITGES CONFERENCE JAMMING,YIELDING, AND IRREVERSIBLE DEFORMATION

Dense merging of clusters: Undense merging of clusters: the exponent reads: one over superdimension (cluster-radius fluctuations) XIX SITGES CONFERENCE JAMMING,YIELDING, AND IRREVERSIBLE DEFORMATION the exponent reads: space dimension over space superdimension specific volume fluctuations REDUCED VARIANCES AS MEASURES OF HYPERVOLUME FLUCTUATIONS

An important fluctuational regime of d-DIMENSIONAL MATTER AGGREGATION COUPLED TO STRESS RELAXATION FIELD XIX SITGES CONFERENCE JAMMING,YIELDING, AND IRREVERSIBLE DEFORMATION fluctuational modeHall-Petch contribution

AT WHICH BASIC GROWTH RULE DO WE ARRIVE ? HOW DO THE INTERNAL STRESS RELAX ? Answer: We anticipate appearence of power laws. Bethe-lattice generator: a signature of mean-field approximation for the relaxation ? It builds Bethe latt. in 3-2 mode XIX SITGES CONFERENCE JAMMING,YIELDING, AND IRREVERSIBLE DEFORMATION - d-dependent quantity - a relaxation exponent based on the above

ABOUT A ROLE OF MEAN HARMONICITY: TOWARD A ‘PRIMITIVE’ FIBONACCI SEQUENCING (model colloids)? Remark: No formal proof is presented so far but... They both obey mean harmonicity rule, indicating, see [M.H.] that the case d=2 is the most effective !!! CONCLUSION: Matter aggregation (in its late stage) and mechanical relaxation are also coupled linearly by their characteristic exponents... XIX SITGES CONFERENCE JAMMING,YIELDING, AND IRREVERSIBLE DEFORMATION

CONCEPT of Random Space – Filling Systems * Problem looks dimensionality dependent (superdimension!): Any reasonable characteristics is going to have (d+1) – account in its exponent’s value. Is this a signature of existence of RCP (randomly close-packed) phases ? * R.Zallen, The Physics of Amorphous Solids, Wiley, NY,1983

 UTILISING A HALL-PETCH (GRIFFITH) LIKE CONJECTURE ENABLES TO COUPLE LATE-STAGE MATTER AGGREGATION AND MECHANICAL RELAXATION EFFECTIVELY  SUCH A COUPLING ENABLES SOMEONE TO STRIVE FOR LINKING TOGETHER BOTH REGIMES, USUALLY CONSIDERED AS DECOUPLED, WHICH IS INCONSISTENT WITH EXPERIMENTAL OBSERVATIONS FOR TWO- AS WELL AS MANY-PHASE (SEPARATING) VISCOELASTIC SYSTEMS  THE ON-MANY-NUCLEI BASED GROWTH MODEL, CONCEIVABLE FROM THE BASIC PRINCIPLES OF MNET, AND WITH SOME EMPHASIS PLACED ON THE CLUSTER SURFACE, CAPTURES ALMOST ALL THE ESSENTIALS IN ORDER TO BE APPLIED TO SPACE DIMENSION AS WELL AS TEMPERATURE SENSITIVE INTERACTING SYSTEMS, SUCH AS COLLOIDS AND/OR BIOPOLYMERS (BIOMEMBRANES; see P.A. Kralchevsky et al., J. Colloid Interface Sci. 180, 619 (1996))  IT OFFERS ANOTHER PROPOSAL OF MESOSCOPIC TYPE FOR RECENTLY PERFORMED 2D EXPERIMENTS CONSIDERED BASED ON MICROSCOPIC GROUNDS, e.g. F. Ghezzi et al. J. Colloid Interface Sci. 251, 288 (2002) XIX SITGES CONFERENCE JAMMING,YIELDING, AND IRREVERSIBLE DEFORMATION CONCLUSIONS

LITERATURE: - A.G. (mini-review) Nonlinear Phenomena in Complex Systems 3, (2000) - J.M. Rubi, A.G. Physica A 326, (2003) - A.G., J.M. Rubi Chemical Physics 293, (2003) - A.G. Modern Physics Letters B 11, (1997) ACKNOWLEDGEMENT !!!