Optimal Structural Design in Rheology

1971 ◽  
Vol 38 (1) ◽  
pp. 39-46 ◽  
Author(s):  
Michal Z˙yczkowski
Keyword(s):  
Stress Relaxation ◽  
Structural Design ◽  
Critical Time ◽  
Optimal Shape ◽  
Optimal Structural Design ◽  
Time To Rupture ◽  
Creep Buckling ◽  
Constant Shape

Typical objectives of structural design and typical constraints in rheology are discussed and classified. They are divided into two groups: the objective may depend on time (creep velocities, creep displacements, stress relaxation), or may be independent of time (time to rupture, critical time in creep buckling problems). The optimal shape may be either constant in time (called here “absolute optimum”), or a function of time (temporary optimum). The latter case is of restricted engineering interest; the notion of “engineering optimum” is here introduced (constant shape, not strictly optimal). Several problems are treated in detail.

Optimal Structural Design Under Creep Conditions

1988 ◽  
Vol 41 (12) ◽  
pp. 453-461 ◽  
Author(s):  
Michał Z˙yczkowski
Keyword(s):  
Structural Design ◽  
Elevated Temperatures ◽  
Future Research ◽  
Structural Elements ◽  
Metal Structures ◽  
Optimal Structural Design ◽  
Creep Buckling ◽  
Creep Stiffness ◽  
Plates And Shells

Optimal design of structures, or rather just of simple structural elements working under creep conditions, belongs to the most recent branches of structural optimization: It was initiated by four papers published in the years 1967–1968 (Reitman, Prager, Nemirovsky, and Z˙yczkowski). The most important differences with respect to elastic or plastic design are as follows: factor of time appearing in the constraints, a great variety of constitutive equations of creep or viscoplasticity, of creep rupture hypotheses, creep buckling theories, various definitions of creep stiffness, etc. Moreover, the constraints related to stress–relaxation are quite new. So, it is almost impossible to establish a sufficiently general theory and various types of problems must be treated separately by appropriate methods. On the other hand, the problems of optimization under creep conditions are important in view of metal structures working at elevated temperatures, structures made of plastics, concrete, etc. The paper gives classification of problems and then a review of results obtained for bars, columns, arches, trusses, frames, plates, and shells. Over 30% of those results were obtained at the Technical University of Cracow. This paper discusses specific features of the branch of optimal structural design under consideration as well as perspectives of future research.

Buckling of Columns in the Presence of Creep

1956 ◽  
Vol 7 (2) ◽  
pp. 125-134 ◽  
Author(s):  
Sharad A. Patel
Keyword(s):  
Critical Time ◽  
Secondary Creep ◽  
Plastic Deformations ◽  
Creep Buckling ◽  
Elastic And Plastic Deformations

SummaryThis paper is concerned with the solution of the creep buckling of columns. Instantaneous elastic and plastic deformations, as well as the transient and secondary creep, are considered. Formulae for the critical time at which a column fails are presented for integral values of the exponents appearing in the creep law.

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