# A Decommissioned Wind Blade as a Second-Life Construction Material for a Transmission Pole

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## Abstract

**:**

## 1. Introduction

## 2. BladePole Configuration, Modelling and Analysis

## 3. Comparison of Results with Governing Code Requirements

_{n}is the nominal strength, γ

_{i}is the load factor, Q

_{ni}is the load effect, and F.S. is the safety factor.

_{M}) from the EC design guidance document are used. The material partial safety factors for FRP materials detailed in the EC guidance are a combination of several contributing partial factors. For uncertainties related to the material properties, γ

_{M}

_{1}is taken as 1.35. This assumes that the properties are derived from theoretical models (note that this value will be reduced in future work by the plan underway by the authors to test specimens from actual decommissioned wind turbine blades). For uncertainties related to the nature of the constituent parts and the production method, γ

_{M2}is taken as 1.35. This assumes production processes and properties with a standard deviation ≤0.10. If no post curing of the composite is used, then γ

_{M2}is further multiplied by 1.2. Thus, the partial material safety factor γ

_{M}= 1.35 × 1.35 × 1.2 = 2.187. The nominal material properties were obtained using Helius Composite software [28]. The overall safety factor and allowable stresses obtained using this design method were calculated using Equations (3) and (4).

## 4. Conclusions

- The BladePole application was shown to be adequate in ultimate and serviceability design limit states, in which the lowest safety factor is 4.19 and the maximum deflection is below the limit of 8% of the aboveground height (AGH).
- The current configuration is intended for a 31.7 m high transmission pole; however, longer or shorter lengths of the wind blade can be cut to suit different heights and voltages.
- The current configuration was designed and checked for a single circuit structure; however, double circuit configuration can be used and will create a degree of symmetry which may enhance the overall stress distribution and safety margins.
- The BladePole application might be suitable for other situations (e.g., dead-end or corner pole applications), but these applications must be carefully analyzed as they have higher longitudinal and transverse loads.
- Further analyses need to be conducted (e.g., finite element analyses) to analyze other limit states and complex load cases (e.g., galloping of conductors, vortex shedding of wind blades, and effect of lift and drag on a wind blade configured as a BladePole). Additionally, effect of material aging needs to be investigated to ensure material integrity in second-life applications.

## Author Contributions

## Funding

## Data Availability Statement

## Conflicts of Interest

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**Figure 1.**Clipper C96 blade configured as a tangent pole application (dimensions have been rounded to one decimal point).

**Figure 3.**Axial force, shear, and moment diagrams for: (

**a**) load case 1; (

**b**) load case 2; and (

**c**) load case 3.

**Figure 4.**Diagrams for: (

**a**) controlling axial stresses from load case 1; (

**b**) controlling axial stresses from load case 2; (

**c**) controlling shear stresses from load case 2; and (

**d**) controlling shear stresses from load case 3.

**Figure 5.**Deflections for: (

**a**) vertical direction from load case 1; (

**b**) transverse direction from load case 1; and (

**c**) longitudinal direction from load case 3.

**Table 1.**Nominal strengths, allowable stresses, calculated stresses, and safety factors for critical load cases.

Stress Type | Station Number | Part Name | Load Case | ||
---|---|---|---|---|---|

Shell | Spar Cap | Web | |||

Nominal Compressive Strength (MPa) | 9 | 197.67 | 543.58 | 145.62 | 1 |

Allowable Compressive Stress (MPa) | 90.39 | 248.55 | 66.58 | ||

Calculated Compressive Stress (MPa) | 44.80 | 41.75 | 13.56 | ||

Safety Factor (Compressive) | 4.41 | 13.02 | 10.74 | ||

Nominal Tensile Strength (MPa) | 9 | 271.65 | 806.82 | 145.62 | 1 |

Allowable Tensile Stress (MPa) | 124.21 | 368.92 | 66.58 | ||

Calculated Tensile Stress (MPa) | 28.91 | 41.68 | 13.54 | ||

Safety Factor (Tensile) | 9.40 | 19.36 | 10.76 | ||

Nominal Compressive strength (MPa) | 10 | 197.67 | 453.47 | 145.62 | 2 |

Allowable Compressive Stress (MPa) | 90.39 | 207.35 | 66.58 | ||

Calculated Compressive Stress (MPa) | 47.20 | 75.90 | 19.82 | ||

Safety Factor (Compressive) | 4.19 | 5.97 | 7.35 | ||

Nominal Tensile Strength (MPa) | 10 | 271.65 | 673.07 | 145.62 | 2 |

Allowable Tensile Stress (MPa) | 124.21 | 307.76 | 66.58 | ||

Calculated Tensile Stress (MPa) | 44.56 | 71.65 | 14.05 | ||

Safety Factor (Tensile) | 6.10 | 9.39 | 10.37 | ||

Nominal Shear Strength (MPa) | 10 | 144.93 | 72.74 | 193.05 | 2 |

Allowable Shear Stress (MPa) | 66.27 | 33.26 | 88.27 | ||

Calculated Shear Stress (MPa) | 3.44 | 5.34 | 8.26 | ||

Safety Factor (Shear) | 42.13 | 13.62 | 23.38 | ||

Nominal Shear Strength (MPa) | 8 | 144.93 | 38.40 | 193.05 | 3 |

Allowable Shear Stress (MPa) | 66.27 | 17.56 | 88.27 | ||

Calculated Shear Stress (MPa) | 11.31 | 4.06 | 20.67 | ||

Safety Factor (Shear) | 12.81 | 9.46 | 9.34 |

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**MDPI and ACS Style**

Alshannaq, A.A.; Bank, L.C.; Scott, D.W.; Gentry, R.
A Decommissioned Wind Blade as a Second-Life Construction Material for a Transmission Pole. *Constr. Mater.* **2021**, *1*, 95-104.
https://doi.org/10.3390/constrmater1020007

**AMA Style**

Alshannaq AA, Bank LC, Scott DW, Gentry R.
A Decommissioned Wind Blade as a Second-Life Construction Material for a Transmission Pole. *Construction Materials*. 2021; 1(2):95-104.
https://doi.org/10.3390/constrmater1020007

**Chicago/Turabian Style**

Alshannaq, Ammar A., Lawrence C. Bank, David W. Scott, and Russell Gentry.
2021. "A Decommissioned Wind Blade as a Second-Life Construction Material for a Transmission Pole" *Construction Materials* 1, no. 2: 95-104.
https://doi.org/10.3390/constrmater1020007