Compression moulding of sheet moulding compound : Modelling with computational fluid dynamics and validation

• Compression moulding experiments of sheet moulding compound, visual observations of a vacuum test with prepregs and numerical models with two main approaches for computational fluid dynamics simulations of the mould filling phase are presen ed. One assumes that there are layers near the mould surfaces with much less viscosity and the other only use one viscosity model. The numerical experiments showed that the pressure could be accurately predicted with both approaches. The property ne essary to predict correct pressure with altered mould closing velocities was that the bulk material had to obey shear-thinni g effects. Preheating effects before compression were neglected, but altering the heating time until the prepreg was assumed to start flow had a significant effect. The experiments confirmed that the pressure is predominantly affected by the mould c osing velocity. Regardless of the considered process settings, a first pressure top always appeared approximately at the logarithmic strain 0.25. A second top was associated with a slowdown of the press. The location of this was affected by the velocity and the vacuum, the latter indicating that vacuum assistance prevents a build-up of back pressure. Furthermore, heated prepreg above a critical temperature is observed to swell immediately as vacuum assistance is applied.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Maskinteknik -- Strömningsmekanik och akustik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Mechanical Engineering -- Fluid Mechanics and Acoustics (hsv//eng)

Nyckelord

compression moulding

computational fluid dynamics

modelling

Sheet moulding compound

Compression molding

Dynamics

Fluid dynamics

Models

Molding

Molds

Shear flow

Shear thinning

Sheet molding compounds

Viscosity

Computational fluid dynamics simulations

Critical temperatures

Logarithmic strain

Numerical experiments

Shear thinning effect

Transport phenomena

Viscosity modeling

Visual observations

Transport properties

Strömningslära

Publikations- och innehållstyp

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