16
2 State of the art
2.2.3 Novel joint designs
The previously introduced sandwich panel joint designs were established decades ago
and they still dominate the industry. At the same time, there are only few studies on
novel joint designs. Roth [Rot05] developed a new manufacturing method for throughthe-thickness reinforcement of established insert types by means of stitching. He reported considerably improved load introduction if compared to state-of-the-art inserts.
However, stitching is mostly limited to foam core sandwich structures and cannot be
readily transferred to honeycomb cores. Schwennen et al. [Sch16] implemented two
novel co-fabrication processes based on resin transfer moulding for integrating highstrength inserts into carbon fiber foam core sandwich. Lim and Lee [Lim11] developed a
novel lightweight insert for co-fabrication into honeycomb sandwich structures. The web
of the insert is sealed and reinforced with carbon composite material. The new design
achieved a weight reduction of 37 % through reduction of potting mass, while achieving
similar tensile strength and 50% increased shear strength if compared to the reference
insert. They complemented the development by the application of a linear FE-model.
Block et al. [Blo05] developed carbon fiber tube inserts as alternative for through-thethickness and partially potted inserts in honeycomb sandwich structures for application
in a spacecraft. They reported improved weight specific strengths given that the insert
tube diameter is larger than 2x the honeycomb cell size.
a)
b)
Figure 14 Examples of novel honeycomb insert designs, a) Carbon fiber tubes [Blo05] and b) Web
reinforced insert [Lim11]
Figure 13 Typical L-joint designs derived from literature [Hex01], [Hei09], [Bit97]
2 State of the art
2.2.3 Novel joint designs
The previously introduced sandwich panel joint designs were established decades ago
and they still dominate the industry. At the same time, there are only few studies on
novel joint designs. Roth [Rot05] developed a new manufacturing method for throughthe-thickness reinforcement of established insert types by means of stitching. He reported considerably improved load introduction if compared to state-of-the-art inserts.
However, stitching is mostly limited to foam core sandwich structures and cannot be
readily transferred to honeycomb cores. Schwennen et al. [Sch16] implemented two
novel co-fabrication processes based on resin transfer moulding for integrating highstrength inserts into carbon fiber foam core sandwich. Lim and Lee [Lim11] developed a
novel lightweight insert for co-fabrication into honeycomb sandwich structures. The web
of the insert is sealed and reinforced with carbon composite material. The new design
achieved a weight reduction of 37 % through reduction of potting mass, while achieving
similar tensile strength and 50% increased shear strength if compared to the reference
insert. They complemented the development by the application of a linear FE-model.
Block et al. [Blo05] developed carbon fiber tube inserts as alternative for through-thethickness and partially potted inserts in honeycomb sandwich structures for application
in a spacecraft. They reported improved weight specific strengths given that the insert
tube diameter is larger than 2x the honeycomb cell size.
a)
b)
Figure 14 Examples of novel honeycomb insert designs, a) Carbon fiber tubes [Blo05] and b) Web
reinforced insert [Lim11]
Figure 13 Typical L-joint designs derived from literature [Hex01], [Hei09], [Bit97]