center for lasers and plasma s for advanced manufacturing

Center for Lasers and Plasmas for Advanced Manufacturing (CLAM)

Center for Lasers and Plasmas for Advanced Manufacturing (CLAM) University of Virginia, Mool C. Gupta, Director, 757.325.6850, [email protected] of Michigan, Jyoti Mazumder, 734.647.6824, [email protected] Methodist University, Radovan Kovacevic, 214.768.4865, [email protected]

Center website: http://www.nsf.gov/eng/I/UCRC/directory/lam.jsp

Hybrid Laser – UltraLight Steel Auto Body (ULSAB) Project

Research at the Center for Lasers & Plasmas forAdvanced Manufacturing (CLAM) has made itpossible to reduce the weight of vehicles andimprove the fuel efficiency and safety. More andmore galvanized steels high-strength steels arebeing used in the automotive industry. All (100%)of the ULSAB-A VC body structure is made of highstrength steel (HSS), with over 80 percent beingAHSS steels (dual phase steels take 74% amongthe AHSS steels). This breakthrough impacts outerbody panels, inner panels, underbody, bumpers, impact beams, and reinforcements and more. Previousmethods required the pre-processing and post-processing actions and are costly to be used in the prac-tice.

This new welding procedure combines the laser welding with the gas tungsten arc welding (GTAW) usedas a preheating source has been successfully developed to lap join the galvanized dual phase steels in agap-free configuration. GTAW leads the laser beam at the specific distance to preheat the work pieces.Under the controlled heat input from the GTAW, zinc coating at the top surface is burned and the metaloxides are generated at the top surface of pieces. Under these welding conditions, a stable “keyhole” isproduced, which provides a channel for the highly pressurized zinc vapor to be vented out. Productivityefficiency is being dramatically increased by this new welding procedure in comparison with the othermethods for welding of galvanized steels in a gap-free lap joint configuration.

Economic Impact: Current practice for laser welding of Zn-coated steel sheet in the automotiveindustry is to provide a slight gap between the two sheets to be welded. The gap allows for thezinc vapor to escape. Problems associated this gap drive additional process costs for each andevery such joint. Therefore, significant savings can be achieved by enabling a zero-gap laser weldcondition.

For more information, contact Shanglu (David) Yang, [email protected].

Hybrid Laser – UltraLight Steel Auto Body (ULSAB) Project 97


Sample of the gap-free lap joints from the hybrid GTAW preheating-laser welding in galvanized dual phase steels.

Experimental setup for hybrid GTAW preheating-Laser welding of galvanized steels in a gap-free lap joint configuration.

98 Hybrid Laser – UltraLight Steel Auto Body (ULSAB) Project


Field Portable Welding of Titanium Tubes

Welding titanium tubes inmilitary aircraft is an exceed-ingly critical and very difficulttask. Ordinarily this process isaccomplished by manufac-turing in super clean opera-tional environments usinghigh-skilled personnel. TheU.S. military not only wouldlike to develop the capabilityto perform welding of tita-nium tubes aboard ships andinto austere, remote areas,but it would also like to avoidusing some of the chemicalstraditionally used to cleantitanium tubes prior to weld-ing. Working with the Centerfor Lasers and Plasmas forAdvanced Manufacturing,the U.S. military has demon-strated that surfaces of titanium tubes can be successfully cleaned using lasers instead of caustic and envi-ronmentally harmful chemicals, thus successfully removing the oxidation layer and any contaminants onthe outside of the tube. This laser technology provides a very accurate method of controlling the depth ofoxide removal in welding. Now that the feasibility of this approach has been demonstrated work is under-way to package the system in a portable, maintainable system for deployment in the field.

Economic Impact: This technology will have economic impact in two ways. First, it reduces theuse of toxic chemicals for surface oxide removal. Second, it lowers the cost of sample preparationprior to welding. It also is a portable system that has military and commercial applications.

For more information, contact Mool C. Gupta, 757.325.6850, [email protected].

Field Portable Welding of Titanium Tubes 99


Extending Damage Limits of Hydraulic Systems in Military Aircraft

Titanium tubing provides thecritical arteries of hydraulic sys-tems in military aircraft. Thetubing is comprised of thin-walled tubes capable of with-standing high pressures in therange of 5,000 psi. Research atthe Center for Lasers and Plas-mas for Advanced Manufactur-ing (LAM) at the University ofVirginia has helped in assessingthe ability to expand the dam-age limits of the tubing; that is,how much sustained damagecan be safely tolerated. Expand-ing the damage limit canreduce maintenance man hoursand reduce operational supportcosts.

Research results have demonstrated that there were additional margins in some areas that translated intoexpanded damage limits. As a result of this work, aircraft are performing much better from a maintainabil-ity standpoint. This should result in considerable savings to the military over the next 15-20 years.

Economic Impact: Knowing the structure damage limits under realistic operating conditionscan avoid the premature failure of components. The premature failure can cause loss of life andfailure of aircraft. For these reasons, this work enhances safety and is having large economicimpacts.

For more information, contact Mool C. Gupta, 757.325.6850, [email protected]

100 Extending Damage Limits of Hydraulic Systems in Military Aircraft


Ultra Lightweight Structures Using Carbon Nanotubes

Ultra lightweight materials capable ofelectronic conduction are needed byNational Aeronautics and Space Adminis-tration and the military. Ultra lightweightelectrically conducting materials wouldprovide structures for ElectromagneticInterference (EMI) Shielding applicationsfor commercial and space applications,development of advanced sensors, lowercost canopy for aircrafts, lightening pro-tection, electronic packaging, printed cir-cuit boards etc. Research at the Center forLasers and Plasmas for Advanced Manu-facturing (LAM) at the University of Vir-ginia has shown that ultra lightweightelectrically conducting materials can beobtained by incorporation of lightweightcarbon nanotubes in polymeric materials.Research has demonstrated that the weight of the nanotubes can be further reduced by conversion tofoam structures. Density of 0.56 gm/cm3 was obtained. These kinds of flexible conductive composites maybe used for typical antenna systems, lightning-protected aircraft composite panels, avionics line replace-able unit (LRU) enclosures, connector gaskets, electrostatic and space charge dissipation materials, and dif-ferent types of electronic pressure sensitive switches or sensors. The University of Virginia has filed a patentapplication on this technology due to its large commercial and defense application potentials.

Economic Impact: Increasing amounts of electromagnetic signals are emanated from variety ofelectronic components. If they are not adequately shielded from external noise these electro-magnetic signals may cause interference of nearby equipment. Electronic shielding of manycomponents is therefore essential. Lightweight electrically conducting nanocomposites will findapplications for shielding of military components, biomedical instruments and of instrumentsused daily life such as cell phones, computers, laptops, radio, CD players etc. The economicimpact of lightweight electrically conducting nanocomposites is substantial but is difficult toquantify.


Ultra Lightweight Structures Using Carbon Nanotubes 101


SEM images of CNT nanocomposite.

Laser Texturing of Surfaces and Commercial Applications

Laser processing provides a uniquemethod of modifying materials surfacesby depositing large amounts of energyonto the surface of a material in a tightlycontrolled manner. Research at the Cen-ter for Lasers and Plasmas for AdvancedManufacturing (CLAM) at the Universityof Virginia has helped to developenhanced textured surfaces on metalsand semiconductors. The laser treatmentcauses pillars to form on the treated sur-face. These pillars provide for greaterlight absorption for solar energy conver-sion, enhanced light detection, improvedtissue growth for body implants, highercatalytic activity, and better heat sinks.This research is leading to the formationof a new high technology company for commercial products and defense applications. Because of its largecommercial and defense application potentials, the University of Virginia has filed an industry supportedpatent application. This technology can be used for solar energy applications for efficient trapping of sunlight incident at different angles. Microtextured surfaces can be used for anti-icing applications.

Economic Impact: Ice buildup is a major problem for commercial and military aircrafts, bladesfor wind energy generation, refrigeration systems, and outdoor antennas. For these reasons, theeconomic impacts of this technology for key industries and for the nation are substantial but dif-ficult to quantify precisely.


102 Laser Texturing of Surfaces and Commercial Applications

center for lasers and plasma s for advanced manufacturing

Documents