**Hybrid:**

**D**: Hybrid conductor design for tip;

**E:** Hybrid conductor design, 2 m on sides;

**F:** Hybrid conductor design, 5 m on sides.

> The parameters examined from the simulation models were:


In addition to the existing parameters, another probe was added to hybrid design at the joints of the two conductors to follow the change in the current density:

6. Current density at joint (kA/m2).

### **5. Simulation Results and Discussion**

### *5.1. Results from Conventional Case Studies*

The graphical representation of the conventional design can be seen in Figure 3, where:


**Figure 3.** Graphical simulation results for conventional design; (**a**) 50 mm<sup>2</sup> cross section area conductor, (**b**) 100 mm<sup>2</sup> cross section area conductor; (**c**) 200 mm<sup>2</sup> cross section area conductor.

As the current from the lightning strike runs from the striking point towards ground (0 V), it heats up the conductor and the blade at the contact surfaces. Due to thermal expansion, the blade and the conductor experience force which causes deformation in both bodies.

#### 5.1.1. Case Study A: Minimal Protection Level with 50 mm<sup>2</sup> Conductor Cross-Section Area

For first case, the conductor cross-section area was set to the minimal recommended 50 mm<sup>2</sup> value where the results of first and subsequent strokes are tabulated in Table 2. Joule heating or resistive heating occurs when electric current passing through a conductor with resistance and it is proportional to the resistance of the conductor and square of the current [36]. The maximum Joule heating occurs close to the attachment point; therefore, the maximum temperature appears at the exact same location. Thus, the highest total deformation can be seen around the tip, where the current enters the conductor.


**Table 2.** Results obtained from the first and subsequent return strokes for **Case Study A.**

### 5.1.2. Case Study B: 100 mm<sup>2</sup> Conductor Cross-Section Area

For this case, the conductor cross-section area was increased to 100 mm<sup>2</sup> where the results are tabulated in Table 3 and it shown that the same parameters observed in Case Study A were decreasing as the cross-section area increases. This has been anticipated as the conductor cross-section increases, it decreases the resistance, therefore the heating and deformation as well.



5.1.3. Case Study C: 200 mm<sup>2</sup> Conductor Cross-Section Area

For this case, the cross-section of the lightning conductor was further increased to 200 mm2. As was expected, the resulting values further decreased as the cross-section increased (Table 4).


**Table 4.** Results obtained from the first and subsequent return strokes for **Case Study C**.

### *5.2. Results from Hybrid Case Studies*

Observing the previously acquired results, the conductor design was constructed to decrease the effects caused by the lightning stroke. By increasing the diameter of the conductor at the tip of the blade, should decrease the impact of the current on the body. The following three cases have been developed and examined with different length of the increased area conductor as depicted in Figure 4.

**Figure 4.** Hybrid conductor designs; (**a**) thicker conductor for tip, (**b**) thicker conductor for tip with 2 m on sides, (**c**) thicker conductor for tip with 5 m on sides.

#### 5.2.1. Case Study D: Hybrid Conductor Design for Tip

In this case, the conductor cross-section area at the tip of the blade has been increased to 100 mm2, meanwhile the rest of the conductor has been left at the minimum recommended value. Assuming that the change in diameter of the attachment area, the impact of the lightning strike attached on the conductor reduced as anticipated where results as tabulated in Table 5.

#### 5.2.2. Case Study E: Hybrid Conductor Design, 2 m Sides

In the second case for the hybrid strategy, the length of the thicker conductor increased for 2 m on the sides of the blade, this hypothetically should further decrease the effects caused by the lightning strike. The results are tabulated in Table 6.


**Table 5.** Results obtained from the first and subsequent return strokes for **Case Study D.**

**Table 6.** Results obtained from the first and subsequent return strokes for **Case Study E.**


5.2.3. Case Study F: Hybrid Conductor Design, 5 m Sides

The thicker portion of the conductor has been further increased to 5 m on each side of the tip of the blade, in theory, further reducing the recorded values where results are tabulated in Table 7.

> **Table 7.** Results obtained from the first and subsequent return strokes for **Case Study F.**

