Fracture of metal/polymer/metal assemblies: Viscoelastic effects

Abstract It is proposed that tire-pavement friction is controlled by thermal rather than by hysteresis and viscoelastic effects. A numerical model of heating effects in sliding is described in which the friction coefficient emerges as a dependent variable. The overall results of the model can be expressed in a closed form using Blok's flash temperature theory. This allows the factors controlling rubber friction to be recognized directly. The model can be applied in quantitative form to metal-polymer-ice contacts. Several examples of correlation are given. The difficulties of characterizing the contact conditions in tire-pavement friction reduce the model to qualitative form. Each of the governing parameters is examined in detail. The attainment of higher friction by small, discrete particles of aluminum filler is discussed.

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A Mixed Numerical-Experimental Method to Characterize Metal-Polymer Interfaces for Crash Applications

Metals ◽

10.3390/met11050818 ◽

2021 ◽

Vol 11 (5) ◽

pp. 818

Author(s):

Jonas Richter ◽

Moritz Kuhtz ◽

Andreas Hornig ◽

Mohamed Harhash ◽

Heinz Palkowski ◽

...

Keyword(s):

Experimental Parameter ◽

Dissimilar Materials ◽

Calibration Method ◽

Parameter Determination ◽

Failure Behavior ◽

Cohesive Elements ◽

Interface Failure ◽

Wide Range ◽

Polymer Metal ◽

Metal Polymer

Metallic (M) and polymer (P) materials as layered hybrid metal-polymer-metal (MPM) sandwiches offer a wide range of applications by combining the advantages of both material classes. The interfaces between the materials have a considerable impact on the resulting mechanical properties of the composite and its structural performance. Besides the fact that the experimental methods to determine the properties of the single constituents are well established, the characterization of interface failure behavior between dissimilar materials is very challenging. In this study, a mixed numerical–experimental approach for the determination of the mode I energy release rate is investigated. Using the example of an interface between a steel (St) and a thermoplastic polyolefin (PP/PE), the process of specimen development, experimental parameter determination, and numerical calibration is presented. A modified design of the Double Cantilever Beam (DCB) is utilized to characterize the interlaminar properties and a tailored experimental setup is presented. For this, an inverse calibration method is used by employing numerical studies using cohesive elements and the explicit solver of LS-DYNA based on the force-displacement and crack propagation results.

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INFLUENCE OF THE DYNAMICS OF FORCED MOTION ON THE STATIC FRICTION IN METAL-POLYMER SLIDING PAIRS

Tribologia ◽

10.5604/01.3001.0015.4897 ◽

2021 ◽

Vol 295 (1) ◽

pp. 21-26

Author(s):

Mariusz Opałka ◽

Wojciech Wieleba ◽

Angelika Radzińska

Keyword(s):

Relative Motion ◽

Friction Pair ◽

Polymeric Materials ◽

Static Friction ◽

Metallic Materials ◽

Test Results ◽

Friction Resistance ◽

Rate Of Increase ◽

Polymer Metal ◽

Metal Polymer

The resistance during the frictional interaction of polymeric materials with metallic materials is characterized by a significant dependence on the dynamics of the motion inputs. In a metal-polymer friction pair, the static friction resistance during standstill under load depends on the rate of growth of the force causing the relative motion. Tribological tests of selected (polymer-metal) sliding pairs were carried out. The selected polymers were polyurethane (TPU), polysulfone (PSU), and silicone rubber (SI). They interacted with a pin made of normalized C45 steel under unitary pressure p = 0.5 MPa in dry friction conditions at different gradients of the force driving the relative motion (dF/dt = 0.1-20 [N/s]). The static friction coefficient of the selected sliding pairs was determined on the basis of the recorded static friction force values. The test results show a significant influence of the rate of increase in the motion driving force on the values of static friction resistance. This is mainly due to the viscoelastic properties of polymers.

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