Keywords: mortise and tenon structure, strength enhancement, composite materials

The mortise and tenon structure is the core connection method of wooden crafts, but its tensile and shear strength is often insufficient, and reliability needs to be improved through material innovation and structural optimization.

1. Improved design of traditional mortise and tenon joints

Optimization of dovetail angle:

By simulating the stress distribution of dovetail tenons at different angles (8 ° -15 °) through finite element analysis (FEA), it was found that the shear strength was highest at 12 ° (25% higher than 9 °), and the processing difficulty was moderate.

Round bar tenon arrangement density:

At the connection between tables and chairs, for every 2mm increase in the diameter of the round bar tenon, the pull-out resistance increases by 40%, but too many tenon holes will weaken the strength of the wood. Experiments have shown that the optimal comprehensive performance is achieved when the spacing is three times the diameter (such as 8mm diameter round bar tenons with a spacing of 24mm).

2. Composite material reinforcement technology

Carbon fiber cloth reinforcement:

Paste unidirectional carbon fiber cloth (thickness 0.1mm) at the mortise and tenon joint, and cure it with epoxy resin to increase the bending strength by 60% (from 30MPa to 48MPa), suitable for large wood carving brackets.

Glass bead filling:

Hollow glass microspheres (particle size 10-100 μ m) are mixed into epoxy adhesive at a volume fraction of 20% to reduce density by 30% while ensuring adhesive strength, thus reducing the weight of handicrafts.

3. Innovation in 3D printing mortise and tenon joints

Topology optimization mortise and tenon:

Using Altair OptiStruct software for topology optimization of mortise and tenon joints, after removing 30% of non load bearing materials, it is manufactured through 3D printing of nylon 12 (PA12), which increases the strength by 15% compared to traditional mortise and tenon joints and can achieve complex curved surface connections.

Multi material printing:

Using a dual nozzle 3D printer, hard PLA (hardness 80 Shore D) is printed on the tenon area, and flexible TPU (hardness 60 Shore A) is printed on the mortise area, achieving self-locking function through material elasticity differences.

4. Industry application cases

In an ancient building restoration project, the arch of wooden architecture structure was strengthened, and the composite process of "carbon fiber cloth+glass bead glue" was used to increase the bearing capacity of a single arch of wooden architecture from 5 tons to 12 tons, meeting the modern seismic requirements.

Future trend: Shape memory alloy (SMA) mortise and tenon joints are currently under development, which can achieve automatic reset after earthquakes or overturn traditional seismic design logic through temperature triggered shape recovery.