Overview

This research laboratory focuses on the characterization and modeling of materials and structures at multiple length scales for a variety of applications, including flapping wing micro-air vehicles, bio-inspired robotics, and multifunctional structures.

Research focus areas

Current focus areas of the MML include the following:

• Multi-scale deformation characterization of hierarchically-structured polymer composites: Utilizing advanced testing techniques based on Digital Image Correlation and nanoscale to macroscale loading systems, we can understand material and structural deformation response from the microstructural aspects to the macrostructural system. This provides the foundation for refining the development of models that require simplification of the complexity of the structure at each length scale in order to provide non-linear deformation response criteria and identification of different failure mechanisms. For example, we have characterized the behavior of the fiber-matrix interface in hierarchically-structured polymer composites in order to identify how load is transferred at the microscale for failure initiation and then characterized macroscopic response in the polymer composite as the failure evolves.
• Indirect characterization of mechanical property distributions in composites: Many materials and structures have complex material distributions which manifest themselves through point-to-point variations in properties. We have developed techniques using indentation testing and Digital Image Correlation to indirectly characterize the mechanical property distributions that are not as easily ascertained using direct methods. For example, we have been able to characterize graded property variations on the nanoscale to microscale in multi-layered and graded composites using new nanoindentation analyses.
• Small-scale testing methods for combinatorial development of polymer composites: Formulation of new polymer composites requires combinatorial approaches for rapid identification of processing-property-structures development. Using a graded polymer composites, we have developed a testing method that enables identification of these relationships using small-scale specimen testing in our customized biaxial microtensile tester. For example, we have recently used this approach to identify the effects of nanofiber loading and twin-screw extrusion processing conditions on the mechanical properties of polymer nanocomposites.

Facilities

Microstructural and Nanostructural Characterization:

• Hysitron Nanoindenter with Modulus Mapping and Dynamic Mechanical Analysis
• Unitron Versamet II inverted Metallographic Microscope with 5 megapixel Digital Camera, Nomarski Prism, and Polarizers
• Wilson Tukon Microhardness Tester
• DME Dual Scope non-contacting AFM Objective with 40 ?m maximum/56.6 nm minimum image size, 2.7 ?m vertical range, and 1.6 pm vertical resolution.
• Buehler Low Speed Diamond Saw
• Buehler Minimet Polisher
• VWR Scientific Ultrasonic Bath with Digital Temperature Control
• 4' x 6' Newport Optical Table with XL-B pneumatic isolation mounts

Mechanical and Thermal Characterization:

• Digital Image Correlation deformation analysis software
• Customized biaxial microtensile test system with integrated AFM and optical microscopy and load ranges of 25 and 2.5 N with picomotor displacement control
• Qimaging Retiga 10-bit 1.3 Megapixel CCD camera with zero-defect sensor and 105 mm Nikon Telescopic Lens
• Imada 500 lb load frame
• Carver 25 kip hydraulic press
• Infrared and fine gage bare wire thermocouples

Computational Modeling:

• Dual-core Pentiums up to 2.8 GHz with 4 GB of RAM
• Computational Software: Windows XP, Visual C++, Abaqus, Matlab

Hugh Bruck Professor 301-405-8711 | bruck@umd.edu Profile