Laser Dynamic Forming Research Articles

Deformation Behaviors and Critical Parameters in Microscale Laser Dynamic Forming

Microscale laser dynamic forming (μLDF) is a novel microfabrication technique to introduce complex 3D profiles in thin films. This process utilizes pulse laser to generate plasma to induce shockwave pressure into the thin film, which is placed above a microsized mold. The strain rate in μLDF reaches 106–107 S−1. Under these ultrahigh strain rates in microscale, deformation behaviors of materials are very complicated and almost impossible to be measured in situ experimentally. In this paper, a finite element method model is built to simulate the μLDF process. An improved Johnson–Cook model was used to calculate the flow stress, and the Johnson–Cook failure criterion was employed to simulate failure during μLDF. The simulation results are validated by experiments, in which the deformation of Cu thin foils after μLDF experiments are characterized by scanning electron microscopy and compared with simulation results. With the verified model, the ultrafast μLDF process is generally discussed first. A series of numerical simulations are conducted to investigate the effects of critical parameters on deformation behaviors. These critical parameters include the ratio of the fillet radius to film thickness, the aspect ratio of mold, as well as laser intensities. The relationship of laser pulse energy and the deformation depth is also verified by a series of μLDF experiments.

Laser dynamic forming of functional materials laminated composites on patterned three-dimensional surfaces with applications on flexible microelectromechanical systems

Laser dynamic forming (LDF) is a three-dimensional (3D) forming technique, which utilizes laser to induce shock wave and shape the target thin films onto micro/nanoscale 3D surfaces. This technique has been used to form metals on 3D surfaces. This letter extends LDF to functional and brittle materials sandwiched by elastomeric polymers on patterned 3D surface. The elastomeric polymers absorb the shock energy and minimize the degradation of the functional materials. The patterned 3D surfaces control the plasticity in the structure and therefore retain the function of the structure. The performance was evaluated and mechanisms were studied.

Microstructure and mechanical property characterizations of metal foil after microscale laser dynamic forming

This article discusses the feasibility of a new microforming technique—laser dynamic forming (LDF). LDF is a new hybrid forming process, combining the advantages of laser shock peening, and metal forming, with an ultra high strain rate forming utilizing laser shock waves. Experiments are conducted on copper foils to demonstrate this forming process. After the forming process, the mechanical and microstructure of the formed work piece will be characterized. Electron backscatter diffraction will be used to investigate the grain microstructure and misorientations quantitatively. The residual stress distributions will be measured using x-ray diffraction. The key factors for the improved formability of this high strain rate microforming process will be discussed in detail. With further development, LDF may become an important microforming technology for various materials.