Mechanical University

CRISTESCU, Nicolaie D., Ph.D.

Graduate Research ProfessorDepartment of Aerospace Engineering, Mechanics

& Engineering Science, University of Florida.

Gainesville, Fl. 32611-6250

Phone: 352-***-****, FAX 352-***-****

e-mail: abp4mi@r.postjobfree.com.

PERSONAL RECORDDate of Birth: Feb. 17, 1929.

Place of Birth: Chelmenti, Romania.

Marital Status: Married, 1 child.

Citizenship: U.S.A

SCHOLASTIC TRAINING1951 Bucharest University, Romania Diplomat

1955 Romanian Academy, Romania Ph.D.

1967 Bucharest University, Romania Docent (equiv. Doctor Habil)

EXPERIENCE1951 to 1955 Assistant Professor, University of Bucharest,

Romania

1955 to 1957 Lecturer, University of Bucharest, Romania

1957 to 1966 Associate Professor, University of Bucharest, Romania

1966 to 1992 Professor, University of Bucharest, Romania

1982 to 1990 Department Chairman, University of Bucharest, Romania

1990 to 1992 President of the University (Rector), University of Bucharest

1968 to 1969 Visiting Professor, The Johns Hopkins University, Baltimore

1969 summer Visiting Professor Drexel University, Philadelphia

1970 to 1976 Visiting Graduate Research Professor, University of Florida

(2 to 6 months/year)

1992 to Date Graduate Research Professor, University of Florida.

FIELDS OF INTEREST

Mechanics of solid deformable bodies, Theory of Plasticity, Dynamic Plasticity,

Rheology, Rock and Soil Mechanics, Mechanics of Particulate Materials.

Expertise and Research Interests.

Cable dynamics. The first research interest has

been in the domain of extensible strings and cables: elastic, visco-elastic,

viscoplastic. Mainly non-linear stress-strain relations of rate type have

been considered as well as finite deformations. Three dimensional equations

of motions, properties and interaction between longitudinal and transverse

waves, order of propagation, reflection from fixed or moving points and

shock waves in extensible cables have been studied. As applications have

been considered: the motion of two bodies connected by an extensible cable,

the braking of a fast moving body by a stretched cable, etc.

Dynamic Plasticity. Research has been carried out

in the domain of dynamic deformation of elastic/plastic materials

(metals, soils and rocks, plastics). Both elastic-plastic and elastic-viscoplastic

waves have been considered. The nature of plastic waves, why the plastic

waves are coupled, i.e. why they are simultaneously dilatational and shearing

waves, the combined dilatational-shearing loading in plates and membranes,

etc. were the investigated problems. The fundamental problem of plasticity

has been addressed: finding the mathematical models able to describe the

rapid plastic deformation of metals. New elastic/viscoplastic constitutive

equations were proposed which would be able to describe dynamic relaxation,

overstress, propagation of waves in plastic bodies with elastic velocities.

Several papers were devoted to the longitudinal impact of aluminum bars,

interaction between elastic (loading and unloading) waves and plastic waves

and how the experimental data can be used to formulate an appropriate constitutive

equation. Numerical procedures have been developed for time-dependent and

time-independent constitutive equations in order to describe the dynamic

loading and unloading of metallic bars. Comparison of theoretical prediction

with the data are excellent.

The characteristics of the plastic waves, as described by various constitutive

equations, was investigated. It has been shown that according to the classical

theories of plasticity the plastic waves are always coupled, and that the

coupling is due to the way in which the yield condition or work-hardening

condition are involved in these theories. The coupling problem was studied

for rate type constitutive equations as well, and it was shown how various

plastic waves interact. This problem is instrumental in in the selection

of the appropriate constitutive equation for a certain material.

From the other plasticity problems considered let us mention: the dynamic

deformation of elastic/plastic membranes, the Bauschinger effect, the Corona

effect, the torsion of metallic bars at elevated temperatures, etc.

Theories of Metal Working. At the request of several

metallurgical companies mathematical models for metal working were developed.

Departing from existing approaches viscoplastic constitutive equations

were used, since these are able to describe the "speed influence" on plastic

deformation during fast metal working. Theories for fast drawing of wires,

drawing of tubes with fixed plugs, drawing of tubes with floating plugs

or without plugs, hot extrusion using glass as lubricant, use of ultrasonic

fields in metal working, heating due to fast deformation or friction, etc.

were some of the problems solved and industrially applied. These theories

allow the optimization of the metal working process i.e. the reduction

of working forces, correct design of tools, significant increase of working

speed, reduction of the wearing of tools, etc.

Mechanics of Composite Materials. The problem of

dynamic delamination and perforation of laminates was studied. The mechanism

of sequential delamination of composites subjected to a transverse impact

was analyzed. The problem is related to the design of composite plates

with distinct perforation strengths when impacted from one side or another

one.

Rock and Soil Mechanics. The main problem considered

is the formulation of mathematical models able to describe the slow deformation

of rocks around various underground openings. The kind of tests necessary

to formulate such rheological models were analyzed and the procedure was

described in detail. These new rheological models are able to describe

the creep of rocks, both transient and stationary, dilatancy and/or irreversible

compressibility during creep, slow damage taking place during creep, failure

and creep failure, work-hardening, etc. Examples for a variety of rocks, based on own experimental data or experimental data obtained by other

authors, were given. A theory of long-term damage produced by dilatancy

was developed for rocks, where dilatancy is related to the microcracking

energy. A correlation between acoustic emission and the irreversible volumetric

behavior was established. A general procedure to determine the a nonassociated

elastic/viscoplastic constitutive equation for geomaterials was formulated,

and examples for a variety of geomaterials was given (granite, andesite,

rock salt, various kind of coal, dry and wet sand, etc.). Temperature influence

on the elastic/viscoplastic behavior of bituminous concrete was also studied.

Many mining and petroleum engineering problems were solved as: creep, dilatancy

and/or compressibility of rocks around vertical mining shafts or petroleum

wells (taking into account an internal pressure as well), or around deep

caverns, or around horizontal tunnels, etc. The long-term damage around

these openings was also analyzed, as well as instantaneous or long-time

failure. A theory was formulated for the interaction between a creeping

rock (viscoelastic or viscoplastic) and an yielding self-adjusting lining,

for several kinds of yielding linings, including elastic and non-elastic

self-adjusting linings. A mathematical theory for several self-adjusting

linings was developed. The compressibility of a stratum of broken rock

was also described by mathematical models of the elastic/viscoplastic type

and used to show its influence, when such a stratum is placed between an

yielding lining and a creeping rock. Creep of coal in long-wall working

is another problem which was addressed. Several papers concerning creep,

stability, failure, and closure of rectangular caverns and galleries have

been published; the evolution in time of dilatancy and thus of damage in

the surrounding rocks was also analyzed for the cases when the caverns

are subjected to an internal pressure or not. The interaction between rock

creep and internal pressure was also considered.

Recently a theory to describe landslides was formulated

taking into account that under its own weight the soil is compacting and

thus the mechanical properties wary with depth. It is shown that density

is varying linearly with depth, but the yield stress cannot wary linearly.

A procedure to determine a viscoplastic constitutive equation (non homogeneous

Bingham) solely from in situ inclinometer readings was given (no laboratory

tests are necessary). Examples of applications of the theory to several

landslides show very good results.

Particulate Mechanics. The problem addressed is

to find out mathematical models able to describe the mechanical behavior

of particulate materials (compaction, dilation, flow) subjected to a certain

stress field. Triaxial testing devices are used for this purpose for both

dry and saturated powders. It is shown when the powders are compacting

and when they dilate. The incipient powder flow was also studied. A new

triaxial aparatus for testing dry powders at law confining pressures was

invented. The influence of particle size, initial density, air flow, etc.

are considered

Present Projects

Modeling of Damage in Concrete and Geomaterials (Air

Force). The research is aiming at formulation of constitutive

equations to describe the elastic/viscoplastic behavior of concrete and

some geomaterials, subjected to high strain rate deformation. A theory

of damage which would take into account the energy of microcracking as

well, is also to be formulated.

New Constitutive Equation for Rock Salt (BGR

-Germany and SANDIA) . The research continue previous

efforts to formulate a constitutive equation for rock salt, able to describe

instantaneous response, creep and relaxation as well as irreversible volumetric

changes (dilatancy and compressibility) during creep. This model will be

applied to design underground radioactive repositories in salt. Evolution

in time of damage is of major concern for such problems and should ge described

by the constitutive equation.

New Numerical Algorithm in Elastoviscoplasticity with

Application to Geomechanics (National Research Council/Twining

Program). This is a cooperative effort with the Mathematical

Institute of the Romanian Academy to develop numerical algorithms needed

for the solving of geomechanical problems when the constitutive equation

is of elastic/viscoplastic type.

Particulate Mechanics (NSF, and several

Chemical Companies). The projects deals with compaction, dilation

and flowing of particulate materials (ceramics, various chemical products

in the form of powder, or geomaterials containing useful minerals). The

effort is to find out experimentally their dominant mechanical properties,

and to formulate mathematical models (constitutive equations) able to describe

these properties. These models can afterwards be used to design products

with controlled density or porosity, or to find out in what condition they

can flow, or how can they be cutten faster, etc.

AWARDS, MEMBERSHIP AND EDITORIAL POSITIONS

Awards

Fellow of Academia Europaea (European Academy).

1995 Nadai Award of ASME.

Awards for research from Romanian Academy and Romanian Ministry of Education.Member in Editorial Board

Senior Editor and Founder: Int. J. Plasticity (Pergamon). He has served

twice (for several years) as Editor Associate of the Applied Mechanics

Reviews. Editor of Mechanics Research Communications (Pergamon)

Member or past member in the Editorial Board of: Int.J.Mech.Sci (Pergamon),

Impact (Pergamon), Mechanics of Cohesive-Frictional Materials and Structures

(John Wiley & Sons), Acta Mechanica Solida Sinica (Huazhong, Univ.of

Sci. and Technology), Rivista Italiana di Geotecnica, John Wiley

Series "Materials, Modelling and Computation", Revue Roumaine de

Mecanique Appliquee.Organizing Committee of Congresses

Member of European Mechanics Committee (6 years); Inducted to Lifetime

Member of the Society of Scholars from Johns Hopkins University; (Founder)

Int. Soc. for the Interaction of Mechanics and Mathematics; (Founder) American

Rock Mechanics Association; Society for Experimental Stress Anal.; Sigma

Xi; Groupe Francais de Rheologie; Natural philosophy; American Academy

of Mechanics; American Society of Mechanical Engineers; International Society

for Rock Mechanics, Tau Beta Pi Assoc., International Assoc. for Computer

Methods and Advances in Geomechanics, ( Founder) The International Society

for Interaction of Mechanics and Mathematic, Member of the General Assembly

of IUTAM.Member in Organizing Committee of Congresses

The Second Naval Structural Symposium, Brown University, 1960. Invited

General Review Paper.

University Lomonosov, Moscow, 1962. Invited Lecture.

Institute of Mechanics, Academy of Sciences, Moscow, 1962. Invited Lecture.University

of Leningrad, 1963. Invited Lecture.

Symposium on Stress Waves in Anelastic Solids, Brown University, 1963

Member of Organizing Committee.

Institute of Fundamental Technological Research, Polish Academy of Sciences,

Warsaw,/1963 Invited Lecture.

The National Congress of Mechanics, Smolenice, Czechoslovakia, 1963.

Invited Lecture.

Institute of Mechanics, Academy of Sciences, Moscow, 1964. Invited Lecture.

Institute of Mechanics, Sinica Academy, Peking, 1964. Invited Lecture

60 hours.

University Lomonosov, Moscow, 1965. Invited Lecture.

Institute of Fundamental Technological Research, Polish Academy of Sciences,

Warsaw,/1965 Invited Lecture.

Imperial College, London, 1966. Invited Lecture.

Center for Physical Researches, Marseille, 1966. Invited Lecture.

The Annual Conference of German Rheologs, West Berlin. 1966. Invited

Lecture.

The Johns Hopkins University, Baltimore, 1966. Invited Lecture.

The Annual Conference of Mechanics of the Polish Academy of Sciences. Kolobrzeg,

Poland. 1966 Invited Lecture.

The Second Symposium on Metal Working. Prague, Czechoslovakia. 1966 Invited

Lecture.

National Conference of Mechanics of Solid Bodies and Plasticity, Moscow,

USSR. 1967 Invited Lecture.

The 12th International Congress of Applied Mechanics, Standford,

1968, - Session Chairman.

Carnegie-Mellon University, Pittsburgh, 1969. Invited Lecture.

Colloquium on Anelastic Behaviour of Solids, Columbus, USA.1969.- Invited

Lecture.

Sandia Laboratories, Albuquerque, 1970. Invited Lecture.

University of Florida, Gainesville, 1971. Invited Lecture.

Center for Physical Researches, Marseille, 1971. Invited Lecture.

The Annual Conference of Mechanics of the Polish Academy of Sciences, Warsaw,

Poland. 1971 Invited Lecture.

The first International Conference on Structural Mechanics in Reactor Technology,

West Berlin, 1971, - Session Chairman.

The 6th Southeastern Conf. of Theoretical and Applied Mechanics,

Tampa, 1972.- Session Chairman.

The 6th International Congress of Rheology, Lyon, France, 1972.

Session Chairman.

Symposium on Foundation of Plasticity, Warsaw, 1972. Invited General

Report.

Polytechnic Institute of Virginia, Virginia, 1973. Invited Lecture.

University of Sherbrooke, Quebec, Canada, 1973. Invited Lecture.

Research Laboratories of Volkswagen Company, Germany, 1973. Invited Lecture.

The Second International Conference on Structural Mechanics in Reactor

Technology, West Berlin, 1973. Member of Organizing Committee and Session

Chairman.

The 11th National Conference of Society of Engineering Science,

Durham, 1974. Session Chairman.

The 20th Polish Conference of Mechanics of Solids, Poland. 1978.-

Invited Lecture.

The 4th International Symposium on Machines and Technologies

of Metal Working by Nonconventional Methods. Bratislava, Czechoslovakia.

The International Symposium "Plasticity Today" Udine, Italy, 1983. Invited

General Conference.

Technical University of Muenchen, Germany, 1983. Invited Lecture.

Technical University of Berlin, West Berlin, 1984. Invited Lecture.

University of New Mexico, Sandia Laboratories, 1990. Invited Lecture.

Federal Institute for Geological Sciences and Raw Materials, Hannover,

1990. Invited Lecture.

University of Utrecht, Holland, 1990. Invited Lecture.

Catholic University, Leuven, Belgium, 1990. Invited Lecture.

"Plasticity '91" The Third Int. Symp.on Plasticity and its Current Applications,

Grenoble, France, 1991. Member of Organizing Committee,Session

Chairman and Invited Lecture.

Finite inelastic deformations theory and applications. IUTAM Symposium,

August 19-23, Hannover, Germany, Invited Lecture.

Seventh Int. Symposium on Salt, Kyoto, Japan, 1992. Session Chairman. Invited

Lecture.

Int. Symposium on Assessment and Prevention of Failure Phenomena in Rock

Engineering, Istanbul, 1993. - Session Chairman.

"Plasticity '93" The Fourth Int.Symp.on Plasticity and its Current Applications,

Baltimore, USA, 1993. Member of Organizing Committee, Organizer of a Session,

Invited Lecture.

3rd Conf. Mechanical Behavior of Salt, Paris, 1993. Member of Organizing

Committee, Session Chairman, Invited Lecture.

Annual Meeting of Society for Mining, Metallurgy, and Exploration, Albuquerque

1994.-Invited Lecture.

8th Conf. IACMAG, Morgantown, WV, USA, May 1994. Invited Lead Lecture.

The 1st North American Rock Mechanics, Austin, June 1994. Invited Lecture.

The 12th U.S. National Congress of Theoretical and Applied Mechanics, Seattle,

June - July 1994. Organizer of a Symposium and Invited paper.

"Plasticity '95" The Fifth Int. Symp. on Plasticity and its Current Applications,

Osaka, Japan, 1995. Member of Organizing Committee, Organizer of a Session.

Invited Lecture.

"4th Conference on the Mechanical Behavior of Salt" Montreal, Canada, June

1996. - Session organizer. Invited Lecture.

"19th International Congress of Theoretical and Applied Mechanics" Kyoto,

Japan, August 1996. - Co-chairman of the session on "Rock and geomechanics"

"6th Int. Symp. On Plasticity and its Current Applications", Juneau, Alaska,

July - Member of Organizing Committee, Organizer of a Session, Invited

Lecture.

"Thirteenth U.S. National Congress of Theoretical & Applied Mechanics",

June 21-26, University of Florida, Vice-Chair of the Scientific Program

Committee, Chair of the Solid Mechanics and Dynamics Subcommittee. Invited

Lecture.

"Advanced Technologies for Particle Processing" PTF Topical Conference

at the 1998.

AIChE Annual Meeting, Miami Beach, Nov.15-20, 1998. Co-Chair of the Conference;

Co-chair of the Symposium on Advanced Technologies for Powder Mechanics.

"5th Conference on the Mechanical Behavior of Salt" August 1999, Conference

Chairman.

SHORT COURSES AND LECTURESUSSR: 1962, 1963, 1964, 1965.

Poland: 1963, 1965.

China: 1964 (60 hours).

Great Britain: 1967, 1993.

France: 1967, 1971, 1972, 1992, 2003

USA: 1967, 1968, 1969, 1970, 1971, 1972, 1973, 1974, 1993 (18 hours),

1995, 1995 (6 hours) 1990, 1991, 1992, 1993, 1994,1995,1996 (4 h), 1997.

Canada: 1973, 1995.

Germany: 1973, 1983, 1984, 1990, 1992, 1994, 1995, 1999.

Holland: 1990.

Belgium: 1990.

Italy: 1971, 1991, 1993 (13 hours).

Hungary: 1993.

Romania 1992 (20 hours), 1993,1994, 2003

Japan: 1995.

SCIENTIFIC WORKPublished 200 papers in prestigious international journals,

presented 57 papers at international congresses, published 17 textbooks

and monographs..

PhD ADVISING. The following

persons, some of whom today are known scientists or full university professors,

obtained their Ph.D.s under Dr. Cristescu's guidance: G.

Dinca, I. Suliciu, M. Mihailescu, Th. Huidu, O. Martin, L. Dragusin, M.

Constantinescu, M. Sofonea, I.R. Ionescu, D. Florea, Cristian Faciu,

M. Cocu, D. Massier, Oana Cazacu, L. Simionescu, Ioana Luca, I. Paraschiv-Munteanu,

M. Nicolae, I. Molnar, Ani Matei at the University of Bucharest, Romania,

and Ji Shan Jin, Martin Schmidt and Ali Abdel-Hadi at the

University of Florida, Gainesville.

Dr Cristescu have been a member in

the commission of Doctor Habil thesis by

J.F.

Shao from University de Lille, France, 1992; a member in the

Ph.D. Commission for W. Dyess from University of Florida, USA, 1994;

A. Dahou from the University of Lille, France, 1995; M.

Pecker from Mines Institute, Douai, France, 1995;

Uwe Glabisch

from University of Braunschweig, Germany, 1996; and E. Maranini,

University of Ferrara, Italia, 1997.

Contact this candidate