Macro-level mechanical interlocking: A rapid joining approach for additively manufactured compression molded composite panels

Journal Article · Thu Jul 24 00:00:00 EDT 2025 · Composites. Part B, Engineering

DOI:https://doi.org/10.1016/j.compositesb.2025.112851· OSTI ID:3002134

Phadatare, Akash ^[1]; Kumar, Vipin ^[2]; Kim, Seokpum ^[2]; Masum Billah, Kazi Md ^[3]; Saha, Subhabrata ^[2]; Talabi, Segun Isaac ^[2]; Rathod, Neel ^[3]; Nuttall, David ^[2]; Smith, Tyler ^[2]; Hassen, Ahmed Arabi ^[2]; Vaidya, Uday ^[4]

---

1. Univ. of Tennessee, Knoxville, TN (United States)
2. Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
3. Univ. of Houston, TX (United States)
4. Univ. of Tennessee, Knoxville, TN (United States); Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States); Institute for Advanced Composites Manufacturing Innovation (IACMI), Knoxville, TN (United States)

Composite joining typically involves multiple steps, such as drilling and surface treatment, as part of the manufacturing process, which leads to low throughput and long cycle times. In the present study, we demonstrated a macro-level mechanical interlocking (MI) based, rapid joining technique to assemble additively manufactured compression molded (AMCM) panels, enabling the production of parts larger than the mold dimensions. Composite panels made of 20 wt% short carbon fiber reinforced acrylonitrile butadiene styrene (CF/ABS) were joined using MI features of various geometries, namely tree (TR), dovetail (Dov), rectangle 2 (Rect2), and rectangle 1 (Rect1), and their in-plane strength was evaluated. The resultant strength of the tested MI joints reached up to 74 % of the baseline tensile strength (i.e., the ‘no joint’ case). Observations from optical and scanning electron microscopy revealed inadequate polymer diffusion between the adherends, indicating that the joint strength was primarily derived from mechanical interlocking. Additionally, the fracture surfaces exhibited stress-whitening marks, which were characterized using differential scanning calorimetry (DSC). The increase in melting enthalpy suggested local stretching of polymer chains due to MI. Finite element analysis (FEA) indicated that the Rect1 MI feature, which generated the lowest stress concentration, outperformed the others in terms of joint strength, achieving 42 MPa. As a demonstration of the MI joining method, a battery box tray measuring 108 cm × 34 cm using a mold with an effective dimension of 36 cm × 34 cm successfully manufactured, resulting in a part with an area three times larger than the mold. In conclusion, this study presents a promising approach to improving composite joining techniques while minimizing production complexities.

• Research Organization: Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: National Science Foundation (NSF); USDOE Office of Energy Efficiency and Renewable Energy (EERE), Energy Efficiency Office. Advanced Materials & Manufacturing Technologies Office (AMMTO); USDOE Office of Energy Efficiency and Renewable Energy (EERE), Office of Sustainable Transportation. Vehicle Technologies Office (VTO)
• Grant/Contract Number: AC05-00OR22725
• OSTI ID: 3002134
• Journal Information: Composites. Part B, Engineering, Journal Name: Composites. Part B, Engineering Vol. 306; ISSN 1359-8368
• Publisher: Elsevier
• Country of Publication: United States
• Language: English

Related Subjects

In-plane joining
Joint strength
Mechanical interlocking (MI)
Seamless joining
Thermoplastic composite joining