Search results for "lujuusoppi"

Bifurcation method of stability analysis and some applications

2014

In this paper a new approach to the analysis of implicitly given function- als is developed in the frame of elastic stability theory. The approach gives an effective procedure to analyse stability behaviour, and to determine the bifur- cation points. Examples of application of the proposed approach for analysis of stability are presented, more precisely we consider the stability problem of an axially moving elastic panel, with no external applied tension, performing transverse vibrations. The analysis is applicable for many practical cases, for example, paper making and band saw blades.

Shape optimization in contact problems with friction

1985

On stochastic modelling and reliability of systems with moving cracked material

2015

In many industrial processes, such as printing paper, a material travels through a series of rollers unsupported and under longitudinal tension. The value of the tension has an important role in the system behaviour, such as fracture and me- chanical stability. This thesis develops stochastic models for a system in which an elastic, isotropic cracked material travels through a series of spans and studies the probabilities of fracture and instability of the material. The models focus on describing tension variations and initial cracks in the material. Time-dependent tension fluctuations are modelled by the stationary Ornstein-Uhlenbeck process, and the occurrence and lengths of the cracks are…

The stress-strain state and stabilization of viscoelastoplastic, imperfect moving web continuum

2014

On modelling and stability of axially moving viscoelastic materials

2013

On the existence of optimal shapes in contact problems : perfectly plastic bodies

1986

On displacement-velocity coupling and the origin of in-plane stress in orthotropic moving continua

2014

In this paper, we address the problem of the origin of in-plane stresses in continuous, two-dimensional high-speed webs. In the case of thin, slender webs, a typical modeling approach is the application of a stationary in-plane model, without considering the effects of in-plane velocity field. However, for high-speed webs this approach is insufficient, because it neglects the coupling between the total material velocity and the deformation experienced by the material. By using a mixed Lagrange–Euler approach in model derivation, the solid continuum problem can be transformed to solid a continuum flow problem. Mass conservation in the flow problem, and the behaviour of free edges in the two-dime…

Variational principle and bifurcations in stability analysis of panels

2014

In this paper, the stability of a simply supported axially moving elastic panel is considered. A complex variable technique and bifurcation theory are applied. As a result, variational equations and a variational principle are derived. Anal- ysis of the variational principle allows the study of qualitative properties of the bifurcation points. Asymptotic behaviour in a small neighbourhood around an arbitrary bifurcation point is analyzed and presented. It is shown analytically that the eigenvalue curves in the (ω, V0) plane cross both the ω and V0 axes perpendicularly. It is also shown that near each bifur- cation point, the dependence ω(V0) for each mode approximately follows the shape of …