8:00 am – 11:30 am:
M5-Joining of Plastics and Composites
(Moderator: Sergio Amancio)-Room S320H
8:00 am – 8:30 am:
Methods of Polymer Weld Quality Evaluation
Miranda Marcus, Edison Welding Institute
Evaluation of the quality of polymer welds is essential to the development and production maintenance of a welding process. However, it can be challenging to select an evaluation method due to the wide variety of options. A comparison of some popular weld quality evaluation methods is discussed in this paper, as well as the preparation procedures for each and what can be learned from each method.
8:30 am – 9:00 am:
Development of Molecular Diffusion Models for Ultrasonic Welding of PLA
Karla Lebron, Iowa State University
This research focuses on the characterization of bioplastics joined using ultrasonic welding and modeling of temperature distributions and interfacial healing. Polylactic acid (PLA), which is typically derived from starch-rich crops such as corn, was studied. While the measurement of activation energy for interfacial healing at weld interfaces of PLA films has been reported, here, this information is used to predict the weld strength of rigid PLA samples welded by ultrasonics. A characterization of the mechanical properties was completed with a tensile test to determine the effects of amplitude, weld velocity and collapse distance on weld strength. From previous interfacial healing activation energy measurements based on an impulse welding method, it was also possible to predict weld strength. It was found that the most influential parameters were weld time, collapse distance and weld velocity. In general, the model predicted weld strength reasonably well with r2 values between 0.77 and 0.78.
9:00 am – 9:30 am:
Effects of Build Orientation and Fill-level on Mechanical Properties of Fused Deposition Modeling PL
Avraham Benatar, Associate Professor, The Ohio State University
Fusion deposition modeling of PLA was studied to determine the effect of build orientation and fill-level on mechanical properties of tensile test samples. This was used to assist in the design and FDM manufacture of airless tires for the NASA rover competition. It was found that the failure and energy at break increased with increasing fill-level for flat built tensile samples, and there was evidence of crazing prior to failure. For the upright built tensile samples, the effect of fill-level on failure load and energy at break was small for fill-levels between 20% and 80%, with large increase for fill-level of 100%. However, for all fill-levels for the upright build samples, the failure load and energy at break were much lower than for the flat build samples. For tire types, the threaded tire in the upright build orientation has the highest failure load with the lowest deflection.
9:30 am – 10:00 am:
Correlating Ultrasonic Weld Quality with Melt layer Thickness
Alex Savitski, Dukane IAS
Dukane’s recent research has shown that there is correlation between the thickness of the melt layer resultant from ultrasonic welding process and the strength and consistency of the weld. An assumption can be made that this melt layer thickness can serve as a reliable predictor of weld quality. This study was designed to revisit previous data and confirm the observations related to this correlation between melt layer thickness and weld quality, with the end purpose of confirming the validity of this hypothesis.
10:00 am – 10:30 am:
Understanding Meltdown During Quasi-simultaneous Laser Transmission Welding
Philip Bates, Royal Military College of Canada
Meltdown or collapse occurs when molten material flows from the interface during polymer welding. This study shows how several quasi-simultaneous (QS) laser transmission welding (LTW) processing parameters affect meltdown in a T-weld geometry using polycarbonate. The total meltdown depends linearly on the total line energy defined as the product of power and the number of passes divided by the scan speed. Increasing the total scan length increases the critical line energy for meltdown to begin.
10:30 am – 11:00 am:
Research on Temperature Field of Laser Transmission Welding Polycarbonate Based on 3D Real Surface Topography
Zhong Hongqiang, Soochow University
Laser transmission welding is a complicated process with the coupling effect among the unsteady and uneven temperature field, mechanical force, stress and strain and plastic forming flow. The theory based on the ideal contact surface has not satisfied the requirement of practical production. In this paper, the mathematical model of surface roughness profile was built based on Weierstrass-Mandelbrot (W-M) fractal function, the contour welding process for polycarbonate (PC) was simulated with the idea taking real 3-D topography of contact area into account and the effect of laser scan power on the surface topography with different surface roughness was discussed, a combination of a rotary Gaussian volumetric heat source with a Gaussian distribution of surface heat source was proposed. Finally, finite element simulated results agree well with the experiments in contour welding with PC. The experimental study indicates that the laser absorption rate, the welding temperature and the variation of temperature gradients of rough surface are lower than the smooth one.
11:00 am – 11:30 am:
Temperature Field And Fluid Field Simulation Of Laser Transmission Welding Polycarbonate
Yan Tingpei, Soochow University
According to the theory of laser transmission welding (LTW), a 3D transient finite element temperature field and fluid field coupling model based on volumetric heat source and melting and solidification model were built. The moving volumetric heat source of laser transmission welding and boundary conditions were implemented by programming user-define function file written by C language. The temperature filed and fluid field were obtained considering the influence of clamping force. Then distributions of temperature and fluid in heat affected zone were analyzed. The results show that the heat affected zone of opaque part is bigger than that of transparent part. The node of peak temperature is under the weld bead and lags behind the center of laser beam. In the molten pool, the higher the temperature is, the faster the fluid flows. In the Y-Z and X-Z plane, fluid flows to the solid liquid interface and forms two vortexes. Temperature field and velocity field simulation will help to guide and study on laser transmission welding process.