TY - JOUR

T1 - Numerical Investigation of Residual Stresses in Welded Thermoplastic CFRP Structures

AU - Nagel, Lukas

AU - Herwig, Alexander

AU - Schmidt, Carsten

AU - Horst, Peter

PY - 2021/2/2

Y1 - 2021/2/2

N2 - Using thermoplastics as the matrix in carbon fiber-reinforced polymers (CFRP) offers the possibility to make use of welded joints, which results in weight savings compared to conventional joining methods using mechanical fasteners. In this paper, the resulting temperature distribution in the material due to resistance welding is investigated by transient finite element (FE) simulations. To examine the effects on the component structure, a numerical modeling approach is created, which allows determining the residual stresses caused by the welding process. It is shown that the area of the structure, especially near the joining zone, is highly affected by the process, especially in terms of residual stresses. In particular, the stresses perpendicular to the fiber direction show failure relevant values up to a maximum of 221 MPa, which might lead to the formation of microcracks in the matrix. In turn, that is assumed to be critical in terms of the fatigue of welded composite structures. Thus, the suggested modeling approach provides residual stresses that can be used to determine their effects on the strength, structural stability, and fatigue of such composite structures. In a subsequent step, these findings could play an important role in the design process of thermoplastic composite structures.

AB - Using thermoplastics as the matrix in carbon fiber-reinforced polymers (CFRP) offers the possibility to make use of welded joints, which results in weight savings compared to conventional joining methods using mechanical fasteners. In this paper, the resulting temperature distribution in the material due to resistance welding is investigated by transient finite element (FE) simulations. To examine the effects on the component structure, a numerical modeling approach is created, which allows determining the residual stresses caused by the welding process. It is shown that the area of the structure, especially near the joining zone, is highly affected by the process, especially in terms of residual stresses. In particular, the stresses perpendicular to the fiber direction show failure relevant values up to a maximum of 221 MPa, which might lead to the formation of microcracks in the matrix. In turn, that is assumed to be critical in terms of the fatigue of welded composite structures. Thus, the suggested modeling approach provides residual stresses that can be used to determine their effects on the strength, structural stability, and fatigue of such composite structures. In a subsequent step, these findings could play an important role in the design process of thermoplastic composite structures.

KW - Finite element modeling

KW - Polymer– matrix composites (PMCs)

KW - Residual stress

KW - Resistance welding

KW - Thermomechanical behavior

KW - Thermoplastics

UR - http://www.scopus.com/inward/record.url?scp=85104656659&partnerID=8YFLogxK

U2 - 10.3390/jcs5020045

DO - 10.3390/jcs5020045

M3 - Article

AN - SCOPUS:85104656659

VL - 5

JO - Journal of Composites Science

JF - Journal of Composites Science

IS - 2

M1 - 45

ER -