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Simulation-based investigation on the temperature influence in laser transmission welding of thermoplastics

  • Patrick Lakemeyer
  • Volker SchöppnerEmail author
Research Paper
  • 10 Downloads

Abstract

Because of several advantages, e.g., an exact and high energy input, laser transmission welding has become more and more important in the last few years. Due to the contactless energy input, a sufficient process control is a challenge. In industrial production, the process parameters for a good weld seam are qualified by the energy input, which describes the process parameters laser power, laser velocity and irradiation time. These process parameters lead to the welding temperature, which influence the weld seam quality. The question remaining is whether the energy input describes the weld strength sufficiently or whether the welding temperature has a higher influence on the weld quality. In this study, the influence of the energy input on the weld quality is determined for an industrially relevant material combination (PBT ASA-GF20 and PC) in experimental examinations for quasi-simultaneous laser transmission welding. The welding temperature for every design point is calculated and the influence of the temperature on the weld strength is analyzed in an FEM model. In order to compare the influences of the two factors, welding temperature and energy input, a correlation analysis is performed. The correlation analysis shows a higher influence of the welding temperature on the weld strength compared to the energy input. But the energy input is also able to describe the weld strength.

Keywords

Polymer joining Thermoplastics Thermo-mechanical FEM-model Energy input Laser transmission welding Welding temperature 

List of symbols

ASA

acrylonitrile-styrene-acrylonitrile

c

z-transformation

Es

energy input

FEM

Finite element method

F( r)

Fisher-transformation

GF

glass fiber (reinforced)

I0

maximum intensity of the Gaussian laser beam

\( {\overline{I}}_n \)

intensity of simultaneous welding at the surface for the thermal source (\( {\dot{\phi}}_{n,1} \)) in the FEM model

\( {\overline{I}}_n(z):: \)

averaged intensity in the z-direction for the thermal source (\( {\dot{\phi}}_{n,1} \)) in the FEM model

\( {\overline{I}}_{(x)} \)

intensity of simultaneous irradiation

K

absorption coefficient

LTW

laser transmission welding

m

number of design points

N

number of scans

n

numbers of thermal sources

PBT

polybutylene terephthalate

PC

polycarbonate

PL

laser power

pJ

joining pressure

QSW

quasi-simultaneous welding

rσ, T

correlation coefficient of the weld strength and welding temperature

s

range of the confidence interval (z-transformation)

sJ

joining displacement

t

t value

t

process time

tu

time of one scan

\( {\overline{T}}_R \)

averaged ranked welding temperature

TR, i

ranked welding temperature of the design point i

vs

scanning speed

w

laser beam diameter

x

x-coordinate

∆x

width of the thermal source (\( {\dot{\phi}}_{n,1} \)) in the FEM model

z

z-coordinate

∆z

height of the thermal source (\( {\dot{\phi}}_{n,1} \)) in the FEM model

α

significance level

εall

all strain

εijel

elastic strain

εijpl

plastic strain

εijth

thermal strain

\( {\dot{\phi}}_{n,1} \)

thermal source in the FEM model

\( {\overline{\sigma}}_R \)

averaged ranked weld strength

σR, i

ranked weld strength of the design point i

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Copyright information

© International Institute of Welding 2019

Authors and Affiliations

  1. 1.Kunststofftechnik PaderbornPaderborn UniversityPaderbornGermany

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