Adhesives for increasing the bonding strength of in situ manufactured metal-composite joints

Abstract

In this present work, the potential of metallic parts, locally reinforced with a continuous glass fibre reinforced thermoset material, pre-impregnated with an epoxy matrix (prepreg), was evaluated by differential scanning calorimetry (DSC), single-lap shear tests and 3-point bending tests of a metal-composite hybrid hat profile. This technology is evaluated regarding an automotive use case, the DSC experiments in combination with moulding trials have proven curing times below 30 s for a moulding temperature of 180°C. A bonding strength of 13.5 MPa was characterized for a co-cured fibre-reinforced plastic (frp) onto a metallic joining partner. By additionally introducing an epoxy glue film as a bonding agent, which is co-cured together with the frp, the bonding strength can be increased significantly up to 25.4 MPa at the expense of the curing time. The mechanical tests on the hybrid hat profile have shown an increase of energy absorption compared with non-reinforced hat profiles. Here, also an additional glue film extends the performance regarding a co-cured plastic reinforcement without glue film. The influence of the storage conditions of the uncured prepreg materials on the mechanical performance was evaluated by a simulated physical ageing at elevated temperatures, followed by a mechanical characterization of the bonding strength and part performance. Also the effect of different testing temperatures and testing velocities on the capability of the metal-composite hybrid part is illustrated.

Keywords

Thermoset fibre-reinforced plastic co-curing bonding strength

Get full access to this article

View all access options for this article.

References

Thomas

Wehler

Handtke

(2018) Evaluation of relevant process parameters for directly cured thermoset composites on metal parts. In: DGM Hybrid 3rd international conference of materials and structures, Bremen, ATLANTIC Hotel Universum, 18–19 April 2018, pp.146–155. DGM-Deutsche Gesellschaft für Materialkunde e.V.

Lauter

Sarrazin

Tröster

. Joining technologies for hybrid materials consisting of sheet metal and carbon fibre reinforced plastics. In: 1st International conference of the international journal of structural integrity, Porto, Portugal, 25–28 June 2012, vol. 4, no. 4. Bingley: Emerald Group Publishing Limited.

Thomas

Handtke

Wehler

. Co-curing of thermoset composites on metal structures with reduced cycle times for high-volume car applications. In: 12th International conference on composite science and technology, Sorrento, Italy, 8–10 May 2019. https://www-sciencedirect-com-443.web.bisu.edu.cn/science/article/pii/S2214785320323312

Schiel

Dilger

. Kinetic analysis for the determination of cure dependent mechanical properties of adhesives J Mater Des Appl 2014; 228: 228(2): 92–99.

Simon

. Isoconversional methods. J Therm Anal Calorim 2004; 76(1): 123–132.

Prime

. Differential scanning calorimetry of the epoxy cure reaction. Polym Plast Technol Eng 1973; 13(5): 365–371.

Vyazovkin

. Model-free kinetics. J Therm Anal Calorim 2006; 83(1): 45–51.

Thomas

Wehler

Fischer

. Predicting the process-dependent material properties to evaluate the warpage of a co-cured epoxy-based composite on metal structures. Compos A Appl Sci Manuf 2020; 133: 105857.

Lauter

. Entwicklung und Herstellung von Hybridbauteilen aus Metallen und Faserverbundkunststoffen für den Leichtbau im Automobil. Dissertation, University Paderborn, 2014.

10.

Wang

Bobbert

Dammann

, et al. Influences of interface and surface pretreatment on the mechanical properties of metal-CFRP hybrid structures manufactured by resin transfer moulding. J Automot Compos 2016; 2(3–4): 272–298.

11.

Cole

Noel

Hechler

, et al. Room temperature aging of Narmco 5208 carbon-epoxy prepreg. Part I: physicochemical characterization. J Polym Compos 1998; 10(3): 150–161.

12.

Wie

Deng

, et al. Evaluation of glass fibre/epoxy prepreg quality during storage. J Polym Polym Compos 2002; 10(8): 599–606.

13.

Frigione

Kenny

. Thermokinetic effects of the aging of epoxy matrix prepregs for high performance composites. J Polym Compos 2002; 23(4): 530–537.

14.

Grunenfelder

Nutt

. Prepreg age monitoring via differential scanning calorimetry. J Reinf Plast Compos 2012; 31(5): 295–302.

15.

Miller

Sutter

Scheiman

, et al. Study of out-time on the processing and properties of IM7/977-3 composites. Covina, CA: NASA, 2010.

16.

Kim

Centea

Nutt

. In-situ cure monitoring of an out-of-autoclave prepreg: effects of out-time on viscosity, gelation and vitrification. J Compos Sci Technol 2014; 102: 132–138.

17.

Kim

Centea

Nutt

. Out-time effects on cure kinetics and viscosity for an out-of-autoclave (OOA) prepreg: modelling and monitoring. J Compos Sci Technol 2014; 100: 63–69.

18.

Blass

Kreling

Dilger

. The impact of prepreg aging on its processability and the postcure mechanical properties of epoxy-based carbon-fiber reinforced plastics. J Mater Des Appl 2017; 231(1–2): 62–72.

19.

Zhu

(2015) Tensile behavior of glass fiber reinforced composite at different strain rates and temperatures. J Constr Build Mater 2015; 96: 648–656.

20.

Zhu

Huang

, et al. Mechanical characterization of the tensile properties of glass fiber and its reinforced polymer (GFRP) composite under varying strain rates and temperatures. J Polym 2016; 8(5): 196.

21.

Detassis

Pegoretti

Migliaresi

. Effect of temperature and strain rate on interfacial shear stress transfer in carbon/epoxy model composites. J Compos Sci Technol 1995; 53(1): 39–46.

22.

Adams

. The effect of temperature on the strength of adhesively-bonded composite-aluminium joints. J Adhes 1993; 43(1–2): 17–33.

23.

Da Silva

Adams

. Joint strength predictions for adhesive joints to be used over a wide temperature range. J Adhes Adhes 2007; 27(5): 362–379.

24.

Banea

De Sousa

Da Silva

, et al. Effects of temperature and loading rate on the mechanical properties of a high temperature epoxy adhesive. J Adhes Sci Technol 2011; 25(18): 2461–2474.

25.

Banea

Da Silva

Campilho

. Effect of temperature on tensile strength and mode I fracture toughness of a high temperature epoxy adhesive. J Adhes Sci Technol 2012; 26(7): 939–953.

26.

Coelho

Reis

Da Costa-Mattos

. Mechanical behavior of GFRP laminates at varying strain rates and temperatures. Mech Solids Brazil 2011; Ed.1: 103–111.

27.

Koerber

Xavier

Camanho

. High strain rate characterisation of unidirectional carbon-epoxy IM7-8552 in transverse compression and in-plane shear using digital image correlation. Mech Mater 2010; 42(11): 1004–1019.

28.

Okoli

. The effect of strain rate and failure modes in the failure energy of fibre reinforced composites. J Compos Struct 2001; 54(2–3): 229–303.

29.

Pan

Schmidt

. Strain rate effect in material testing of bulk adhesive. J Struct Shock Impact 2006; IX: 107–116.

30.

Paul

Motalab

Zubaer

, et al. Strain rate and curing condition effects on the stress-strain behavior of epoxy adhesive Materials. J Adhes Sci Technol 2017; 31(16): 1782–1795.

31.

Shen

Rutherford

. Study of the performance of adhesive bonded joints. Final report, 1970. U.S. Army aviation material laboratories Virginia.

32.

Liang

Liechti

. On the large deformation and localization behavior of an epoxy resin under multiaxial stress states. J Solid Struct 1996; 33(10): 1479–1500.

33.

Chai

. The effects of bond thickness, rate and temperature on the deformation and fracture of structural adhesives under shear loading. Int J Fract 2004; 130(1): 497–515.

34.

DIN Deutsches Institut für Normung e.V. Plastics - Differential scanning calorimetry (DSC) - Part 1: General principles (ISO 11357-1:2009), Beuth-Verlag, Berlin, 2010.

35.

DIN Deutsches Institut für Normung e.V. Adhesives - Determination of tensile lap-shear strength of bonded assemblies (EN 1465:2009), Beuth-Verlag, Berlin, 2009.