Plummer Laboratory Mechanical Design Assistant
Completed 48 Instron tests across four bistable models and delivered a CNC-machined shaker adapter held to ±0.005 in, reducing estimated plate-and-bolt cost from $1,170 outsourced to $71.11 in-house.
Visit the Plummer Research Group48-Test Bistable-Model Campaign
I developed three specimen concepts for a one-dimensional physical Ising system, which uses bistable buckling beams as two-state mechanical elements. The test campaign provides force measurements for investigating how neighboring beam states affect the response.
I designed the specimens, test matrix, and procedure; operated the Instron 68SC-5; processed the force data; and produced the plots. The 48 tests comprised 32 initial configurations across four models (one legacy and three I developed), 12 repeat tests, two reversed configurations, and two synchronized-camera trials.
Measured forces spanned 0–181 mN, with peak buckling forces of 9–181 mN. I compared peak force immediately before node buckling for configurations with the same immediate neighbors and different next-nearest-neighbor states. This compares buckling thresholds; energy and coupling-coefficient interpretation remains preliminary.
I synchronized camera recordings with the force response to relate beam curvature to applied force. Previous empirical work used curvature measurements; this campaign produced the laboratory’s first direct force dataset for future coupling analysis. The effective coupling coefficient, Jeffective, has not yet been calculated.
I compared ball-bearing, tight-tolerance LEGO-based, and fixed resin-printed joints. The rotating concepts showed scatter and cases where an adjacent beam buckled instead of the loaded beam. My fixed resin-printed joint, installed through a screw-retained slide-in interface, constrained unwanted motion and produced more controlled buckling.
Exact specimen geometry, configuration data, and force comparisons remain unpublished.
Sanitized test architecture. Exact specimen geometry, configuration data, and force comparisons remain unpublished.
Instron 68SC-5 and Synchronized Camera Test Architecture
Structural Design & Dynamic Testing
I designed and machined an adapter mounting a physical Ising-model fixture to the shaker for controlled vibration tests of bistable buckling elements. Estimated plate-and-bolt cost fell from $1,170 outsourced to $71.11 in-house ($67.15 plate, $3.96 bolts).
- Plate trade: Selected a solid 6061-T6 plate over a honeycomb concept: $67.15 versus $159.53 quoted plate cost, simpler in-house machining, and load paths assessable with hand calculations and SolidWorks FEA. Displacement predictions for the separate cases are retained below.
- SolidWorks Dynamic FEA: Predicted 0.44 mm maximum fixture deformation relative to the moving base under a 3 kg payload and 13 mm peak-to-peak base excitation at 20.1 Hz.
- Joint analysis: Checked bored Class 8.8 M10 bolts and the plate under preload plus a separate 5 kg, 11 G load case. Plate bearing governed the two local plate checks at 2.46 FOS; bolt tensile yield gave 1.49 FOS. Thread shear, pull-through, and the load path are detailed below. These static checks do not establish dynamic or fatigue capacity.
FEA & Hand-Calculation Comparison
The design-review plate FEA predicted 0.173 mm maximum displacement, below my selected L/240 limit of 1.27 mm for its 12 in span. A separate Ising-model fixture case predicted 0.080 mm. These review cases are distinct from the later 0.44 mm dynamic fixture prediction.
Precision Manufacturing
Generated CAM/G-code and machined the 6061-T6 adapter on a Haas VF-2 CNC mill, including an underside chamfer, corner fillets, and 12 drilled holes. Checked plate dimensions with calipers against the ±0.005 in drawing tolerance.
Load-path and displacement calculations guided material removal beyond the mounting holes; SolidWorks FEA checked the lightened plate. Machining reduced 3.19 kg stock to a 1.90 kg finished plate, a 40.4% stock-to-part mass reduction.
Applied GD&T and worst-case tolerance-stack analysis, calculated ISO 273 clearances for ISO 4017 M10 hardware, and added 0.5 mm edge breaks. I drilled 5 mm axial bores into standard medium-carbon-steel M10 bolts for the required interface, avoiding custom-bolt procurement. Stainless-steel machining attempts failed, so I changed the bolt material and checked the reduced tensile area; the bored bolts and adapter were installed.
I presented a mini design review of the shaker adapter, covering design iterations, finished hardware, and results, as my flash-talk update at a multi-lab research meeting.
Shaker-plate CAM setup and toolpath simulation
Laboratory Commissioning & Apparatus
I supported the operational build-out of a mechanics-of-materials research laboratory by evaluating and procuring equipment, tooling, and supplies against a $3,500 startup budget.
- High-speed camera mount: Designed, built, and used an adjustable 45 × 45 mm extrusion stand attached to the shaker table with four M6 bolts. A simply supported top-beam model including self-weight predicts approximately 0.107 mm deflection at the 2 kg camera load, or 0.178 mm at a doubled 4 kg design load. These are static predictions, not measured vibration response.
- Reusable Test Infrastructure: Chose long, modular extrusion members so the stand could be reconfigured for future experiments while staying within the $390 budget.
Research Infrastructure
- Developed a hydrogel-saturation fixture with custom 3D-printed hexagonal airflow platforms and COTS fluid hardware. Improved drying uniformity is the design objective; testing is ongoing. Separately performed thermal calibration on legacy ovens up to 68°C for plastics processing.
- Designed tiered contamination-control stations for SLA resin printing, with separated uncured, washed, and cured zones, spill trays, and dedicated tool holders.
- Implemented acrylic chemistry/soldering dividers, custom hazardous-material fixtures, 5S workstation topology, and foam-shadowed tool drawers.
Fixture Calculation Basis
Design-review predictions, later dynamic analysis, and manufacturing results refer to different cases and are kept separate below.
Plate trade and displacement cases
| Initial honeycomb concept | 0.832 kg; 0.002 mm predicted deflection; $159.53 plate quote |
|---|---|
| Selected solid plate | 1.90 kg; $67.15 plate cost |
| Selected plate displacement criterion | L/240 for the 12 in span: 12/240 = 0.050 in (1.27 mm). I selected this span-based serviceability criterion for the 12 × 12 in plate. |
| Review displacement results | 0.173 mm for the plate; 0.080 mm for the Ising-model fixture |
| Later dynamic case | 0.44 mm maximum predicted fixture deflection at 3 kg and 20.1 Hz |
| Base excitation / response reference | 13 mm total peak-to-peak base motion; the 0.44 mm result is fixture deformation relative to that moving base |
Source: August 5 shaker-plate review and subsequent project record. Displacements come from different modeled load cases and cannot be added or treated as a controlled stiffness comparison. The selected L/240 limit is a displacement criterion, not a yield or fatigue check. The review’s 0.173 mm plate prediction is below the 1.27 mm limit for that modeled case. The review describes conservative cantilever-corner hand calculations checked against FEA.
Manufacturing and hardware cost
| In-house plate and bolts | $67.15 + $3.96 = $71.11 |
|---|---|
| Estimated saving from outsourced scope | $1,170 − $71.11 = $1,098.89, or approximately 93.9% |
The estimated 93.9% saving compares plate-and-bolt hardware only; labor and total fixture-system cost are outside this comparison.
Fastener and camera-support analysis
| Fastener tightening torque | 21.7 ft·lbf to achieve the intended Class 8.8 preload |
|---|---|
| Reported fastener load case | 16.36 kN preload + 0.135 kN external load = 16.50 kN (approximately 3,709 lbf) per bolt; 1.49 static FOS against bolt tensile yield; full external load added without joint stiffness sharing |
| Preload model | Fᵢ = (2/3) Sᵧ Aₜ = 16.36 kN per bolt; 1.50 FOS against bolt tensile yield |
| External-load model | Fₑ = (2 kg plate allowance + 3 kg fixture) × 11g = 539.6 N total; divided across four bolts = 134.9 N per bolt |
| Torque estimate | T = KdFᵢ, with K = 0.18 and d = 10 mm: 29.46 N·m (21.7 ft·lbf). K is an assumed nut factor for wet threadlocker. |
| Other static failure-mode FOS values | Recorded model: plate bearing 2.46; pull-through 4.99; external-thread shear 3.71; internal-thread shear 3.60 FOS |
| Plate bearing stress / allowable | 147.1 MPa / 361.5 MPa assumed bearing allowable = 2.46 FOS; allowable modeled as 1.5 × 241 MPa tensile yield |
| Plate pull-through stress / allowable | 34.1 MPa / 170 MPa assumed shear allowable = 4.99 FOS |
| Installed joint dimensions used | 9.7 mm local plate thickness; 9.35 mm thread engagement; 38.35 mm² remaining bolt tensile area after the 5 mm axial bore |
| Camera-support design mass | 2 × 2.0 kg = 4.0 kg conservative static load |
| Camera-support displacement model | δ = PL³/(48EI) + 5wL⁴/(384EI): approximately 0.107 mm at 2 kg, or 0.178 mm at 4 kg, including top-beam self-weight |
| Extrusion model inputs | E = 68 GPa; I = 106,217 mm⁴; simply supported 1,080 mm top beam with center camera load and distributed self-weight |
Source: DSRF Calcs, Class 8.8 M10 sheet. The model uses 5 kg at 11 G, shared equally by four bolts, and conservatively adds the full per-bolt external force to preload. It assumes an M10 × 1.5 tensile area reduced by a 5 mm axial bore (38.35 mm²), 640 MPa bolt yield, and 9.7 mm local bearing thickness. The 5 mm bore and 9.7 mm local bearing thickness match the installed joint. Preload keeps the joint compressed, while bolt and joint stiffness determine how much external tensile load increases bolt tension versus relieves joint compression. The workbook omits that stiffness-sharing calculation and adds the full external load to preload as a conservative static check. The resulting 1.49 FOS is against bolt tensile yield; the preload-only 1.50 FOS describes the initial stress state, not cyclic capacity. Neither ratio establishes overall dynamic performance or fatigue life at 20.1 Hz. Preload scatter, joint separation and fatigue are not quantified in this workbook. All reported failure-mode ratios use nominal properties, not measured bolt strength. Joint load-sharing reference: NASA TM-106943.