The FrykenStaven™: Increased strength, perfect balance. Visit our About page or Sitemap / Link Page to explore all Golden Mosquitos posts and projects. Brief Summary of our patent-pending ski pole design.
TECHNICAL FIELD
This invention relates to ski equipment, and more specifically, to the design, manufacture, and use of reinforced ski poles, particularly for competitive cross-country and roller skiing. The invention further discloses a method for enhancing ski pole performance by strategically placing foam materials with optimized properties within the pole shaft to achieve zonal reinforcement.
BACKGROUND OF THE INVENTION
Competitive cross-country and roller skiing place significant stress on ski poles, frequently leading to breakage. Breakages commonly occur during falls, especially in the middle section of the pole, and multi-skier falls frequently result in broken poles. Traditional ski poles often involve a trade-off between weight and durability. Current reinforcement methods, such as increasing wall thickness or using stronger materials, often increase weight and adversely affect the swing weight, which is crucial for skiing performance.
Problem Addressed by the Invention
Elite skiing poles, designed to be lightweight, are particularly vulnerable to impacts from skis and other poles. A reinforcement method is needed that enhances strength and impact resistance without compromising weight or balance.
Optimization of Ski Pole Selection
Optimal ski poles can vary between competitions depending on factors such as snow conditions, course length and type, and competition type (mass or individual). A skier’s size, strength, arm length, and skiing style all influence the demands placed on their poles. Therefore, a system for selecting pole properties based on individual skier data and track design would be beneficial.
PRIOR ART
Racing ski poles primarily use carbon fibers. Traditional ski poles consist of a circular cross-section hollow shaft, a handle, a basket, and a spike. Designs like those in US Patent No. 5,611,571 (circular cross-section transitioning to a droplet shape) aim to increase rigidity and aerodynamics but can increase weight and instability. European Patent No. 2,308,569 A1 discloses a ski pole with a triangular cross-section, claiming to offer stiffness, high breaking strength, and reduced drag.
Ski Pole Construction and Reinforcement
Epoxy resin is commonly used to reinforce ski poles, though it considerably increases their weight. A 1.5 mm layer can almost double the weight of a carbon fiber pole.
Evaluation of Various Foam Types
Several types of foam are strong, lightweight, and capable of withstanding loads and low temperatures, making them suitable for forming a foam core in a ski pole. Examples include:
- Polyurethane Foam (PU Foam): Lightweight, strong, flexible, and available in a wide range of densities (approx. 20-40 g/liter).
- Polyethylene Foam (PE Foam): Highly light, shock-absorbing, water-resistant, and maintains properties well in freezing conditions (approx. 25-50 g/liter).
- Expanded Polystyrene (EPS): Lightweight and rigid, though it may become more brittle at very low temperatures (approx. 10-30 g/liter).
- Foam Resin: Lightweight foam offering high strength and dimensional stability (approx. 15-50 g/liter).
- Polyisocyanurate Foam (PIR Foam): High heat resistance and excellent insulation capabilities, maintaining strength effectively even at low temperatures (approx. 30-50 g/liter).
DESCRIPTION OF THE INVENTION
This invention reinforces ski poles by strategically placing foam materials with optimized predetermined properties within the pole’s shaft. This method improves strength and impact resistance without increasing weight, reducing the risk of buckling and breakage from compression forces and impacts.
Buckling Analysis
Buckling occurs when a long, hollow structure, like a ski pole, is subjected to a compressive force exceeding its critical load, leading to sudden deformation. Flexural buckling is the most common type, where the pipe bends sideways due to axial compressive loads.
Euler’s Buckling Formula is used to determine the critical load at which a ski pole will buckle:
$$\text{Pcr} = \frac{\pi^2\text{EI}}{(\text{KL})^2}$$
Where:
- $\text{Pcr}$ är den kritiska lasten.
- $\text{E}$ är elasticitetsmodulen (Young’s modulus).
- $\text{I}$ är tröghetsmomentet.
- För en cylindrisk ihålig stav med yttre radie R och inre radie r, ges I av: $\text{I} = \frac{\pi (\text{R}^4 – \text{r}^4)}{4}$.
- $\text{K}$ är knäckningskoefficienten.
- $\text{L}$ är polens effektiva längd.
Factors Affecting Buckling Load include the material’s modulus of elasticity, cross-section shape (moment of inertia), length, and end support.
Measurement Procedure Summary
The pole is segmented into distinct zones of, for instance, five centimeters each, and each distinct zone undergoes stroke and pressure tests. The material’s failure threshold under compression at a specific pole location is stated in MPa, and impact toughness in J, providing a clear picture of the material’s strength and toughness under different load conditions.
Test of Skier Requirements for High-Performance Ski Poles
This method uses skier-evaluated data and defines competition-specific requirements. Individual skier test data, including arm strength, body height, weight, length, poling style, competition type, and fitness level, serve as input parameters to predict the forces and loads on the ski pole. Each pole zone is assigned a minimum stiffness value based on the skier’s needs, and if multiple foam types/densities meet requirements, the lightest option is selected.
Foam Classification
Foam materials are classified by their properties, including stiffness, flexibility, shock and vibration resistance, cold resistance, and weight. A five-point scale categorizes stiffness (1: Very Soft to 5: Very Stiff) to aid in selecting optimal foam for each ski pole zone. Stiffness values of 4 or higher are typically preferred for ski poles.
| Foam Type | Density (kg/m³) | Stiffness Value | Comments |
| PU Foam | 20 | 2 | Suitable for light cushioning. |
| PU Foam | 30 | 3 | Offers medium cushioning and flexibility. |
| PU Foam | 40 | 4 | Provides firm support for structural use. |
| PE Foam | 25 | 1 | Lightweight with minimal stiffness. |
| PE Foam | 50 | 3 | Balanced stiffness and good shock absorption. |
| EPS | 15 | 3 | Lightweight but slightly fragile. |
| EPS | 30 | 5 | High stiffness, ideal for rigid protection. |
| Foam Resin | 30 | 3 | Good balance of flexibility and stiffness. |
| Foam Resin | 50 | 5 | High stiffness, suitable for heavy-duty applications. |
Methods for Inserting Foam in a Pole Shaft
The preferred methods include introducing foam along the pole’s length in a prefabricated foam method, or injecting each foam to achieve the desired proportion, and adjusting the foam expansion rate in specific zones. Introducing foam with a nozzle on a hollow rod from inside of the shaft allows for precise placement and helps prevent shaft wall deformation.
Example Calculation: Amount of Liquid Foam (Expansion factor 20)
- Pole Volume (V): 78,540 mm³ = $78.54 \text{ cm}^3$ (for a 1-meter pole, 10 mm inner diameter).
- Liquid foam needed ($\text{V}_{\text{liquid}}$): V / expansion factor = $78.54 / 20 = 3.927 \text{ cm}^3$.
Example Calculation: Weight of Expanded Foam
- Foam density: 25 grams per liter (0.025 grams per $\text{cm}^3$).
- Weight of foam ($\text{m}$): volume $\times$ density = $78.54 \text{ cm}^3 \times 0.025 \text{ g/cm}^3 = 1.9635 \text{ g}$.
Object of the Invention
The objective is to provide a ski pole shaft that meets users’ requirements for strength and performance with minimal weight gain and is stiffer and has higher breaking strength than prior art pole shafts. This is achieved by classifying foam types based on weight and performance and implementing zonal reinforcement throughout the ski pole, based on each zone’s requirements and tailored to the skier.
Automated Foam Injection System
An automated foam injection system with a single or multi-nozzle injection head is used to achieve precise and consistent foam placement. A robotic drive mechanism moves along the shaft and injects various foam densities at predetermined locations and speeds.
Key Aspects of the Invention
The invention involves:
- Zonal Reinforcement: The hollow pipe is segmented into zones based on desired mechanical properties.
- Foam Selection: Various foam materials are chosen for each zone according to specific characteristics (e.g., high-density foam for impact resistance).
- Simultaneous Application: Selected foam materials are preferably introduced simultaneously using a multi-nozzle injection system for precise placement.
Advantages of the Invention
- Enhanced Strength and Impact Resistance.
- Thin walls: The pole material can be made thinner and lighter, but with increased strength with a strong and user-optimized foam core.
- Targeted Reinforcement.
- Lightweight Design.
- Improved Performance: Tailored stiffness, flexural properties, and optimized swing weight.
- Reduced Risk of Pole Breakage: Foam core maintains structural integrity even with outer casing damage.
Foam Reinforcement Benefits
Foam can prevent buckling and kinking, enhancing structural stability and resistance to buckling through several mechanisms:
- Increased area inertia.
- Support for pipe walls.
- Distribution of load.
- Vibration damping.
Foam Recommendations
Based on lightness, dimensional stability, and shock absorption, foam resin or high-density PU foam can be recommended.
Computer Program Design
A computer program assists in the analysis, design, and optimization of foam-reinforced ski poles. It uses input data from skiers (arm strength, height, weight, style), analyzes it to determine optimal foam type and density, and generates instructions for the automated injection. The system also incorporates a machine learning module that continually refines the recommendations based on test data and outcomes.
Related Topics and Resources
Innovations like FoamSpine™ show how advanced materials can enhance performance and resilience in winter sports. By connecting this technology to broader sustainability and climate adaptation efforts, we highlight how equipment design is part of the larger conversation about protecting both athletes and the environment.
Internal Links
- The Future of Winter Sports: FrykenFrost™ – Race-Ready Snow Guaranteed
- FrykenFrost™ – Surface Cooling System
- Helioshade™: Engineering the Sun — A Scientific Proposal for Planetary Protection
External References
- NASA: Materials Science in Space
- International Ski Federation (FIS): Equipment Regulations
- IPCC Sixth Assessment Report
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