TY - JOUR

T1 - Design and manufacturing optimization of epoxy-based adhesive specimens for multiaxial tests

AU - Wentingmann, Michael

AU - Manousides, Nikolas

AU - Antoniou, Alexandros

AU - Balzani, Claudio

N1 - Funding Information: This work was supported by the German Federal Ministry for Economic Affairs and Energy (BMWi) in the ReliaBlade project (Grant Nos. 0324335A, 0324335B).

PY - 2021/12/15

Y1 - 2021/12/15

N2 - Specimen design and manufacturing quality are decisive factors in the experimental determination of material properties, because they can only be reliably determined if all undesired influences have been minimized or are precisely known. The manufacture of specimens from highly viscous, two-component and fiber-reinforced structural adhesives presents a challenge from this point of view. Therefore, a design and manufacturing optimization procedure for fiber-reinforced structural adhesives and multiaxial testing was developed. It incorporated a finite element parametric study to minimize stress concentrations in the specimen geometry. Vacuum speed mixing was combined with 3D printed mold inserts to enable the manufacture of homogeneous specimens with negligible porosity. The method was demonstrated by means of a structural adhesive used to manufacture wind turbine rotor blades, while the manufacturing quality was verified with high-resolution X-ray microscopy (μCT scanning), enabling detailed detection of pores and geometrical imperfections. The results of uniaxial and biaxial static tests show maximized strength and stiffness properties, while the scatter was minimized in comparison to that stated in international literature. A comparison of the mechanical properties and associated manufacturing techniques is given. The comparison includes a porosity analysis of a specimen from an industrial dosing machine used for rotor blade manufacture.

AB - Specimen design and manufacturing quality are decisive factors in the experimental determination of material properties, because they can only be reliably determined if all undesired influences have been minimized or are precisely known. The manufacture of specimens from highly viscous, two-component and fiber-reinforced structural adhesives presents a challenge from this point of view. Therefore, a design and manufacturing optimization procedure for fiber-reinforced structural adhesives and multiaxial testing was developed. It incorporated a finite element parametric study to minimize stress concentrations in the specimen geometry. Vacuum speed mixing was combined with 3D printed mold inserts to enable the manufacture of homogeneous specimens with negligible porosity. The method was demonstrated by means of a structural adhesive used to manufacture wind turbine rotor blades, while the manufacturing quality was verified with high-resolution X-ray microscopy (μCT scanning), enabling detailed detection of pores and geometrical imperfections. The results of uniaxial and biaxial static tests show maximized strength and stiffness properties, while the scatter was minimized in comparison to that stated in international literature. A comparison of the mechanical properties and associated manufacturing techniques is given. The comparison includes a porosity analysis of a specimen from an industrial dosing machine used for rotor blade manufacture.

KW - Multiaxial testing

KW - Porosity analysis

KW - Structural adhesives

KW - Wind turbine rotor blades

UR - http://www.scopus.com/inward/record.url?scp=85118583182&partnerID=8YFLogxK

U2 - 10.1016/j.matdes.2021.110213

DO - 10.1016/j.matdes.2021.110213

M3 - Article

AN - SCOPUS:85118583182

VL - 212

SP - 1

EP - 14

JO - Materials and design

JF - Materials and design

SN - 0264-1275

M1 - 110213

ER -