## 1 Introduction
As mentioned, swingarm structural behavior is the main topic covered in this research. Based on related literature there are several publications focused on swingarm structural analysis, but they all explore single-sided [10, 11, 12, 13, 14] or double-sided [15, 16, 17] rear swingarms. Double-sided swingarms hold the rear wheel by both sides of its axle, while single-sided ones are a type of swingarm which lies along only one side of the rear wheel and hold it in one side, allowing it to be mounted like a car wheel. In all cases, a static analysis is considered, presenting stress and displacements based on different loading conditions. Focusing on the single-sided swingarms, in [10] the loads applied correspond to maximum traction and lateral bending forces, comparing an aluminum and Carbon Fiber Reinforced Plastic (CFRP) version. A multi objective optimization is performed for the redesign of the carbon fiber version targeting maximum stiffness and minimum weight. [PERSON] [14] presented a similar analysis, towards weight optimization, considering CFRP material. [PERSON] [11,13] also used a static analysis based on torsional and vertical loads, trying to achieve higher torsional stiffness and minimum weight. Considering double-sided swingarms, a relative procedure is followed where structural analysis is based on braking and cornering [15], torsional loads [16], or extreme loading such as performing a wheelie [17]. Regarding material use, the majority is focused on aluminum alloys such as 7075-T6 [15], CFRP [18] and comparisons of aluminum and steel versions [16,17]. Based on the aforementioned literature, other valuable information was also gathered (Table 1), including: a) weight of swingarms developed, b) vehicle motor power and c) safety factor. It is evident that rear swingarm's weight depends on the motor power used on the motorcycle, as well as if it is single or double-sided. In Table 1, double- or single-sided swingarms are defined as (D) or (S), respectively. For motor power less than 40 KW, only double-sided can be found and their weight is 2.6-2.7 kg for aluminum and CFRP versions, respectively. On powertrains ranging between 130 and 185 KW, single-sided swingarms weight is 4.1-4.2 kg for CFRP and 5 kg for aluminum, while double-sided swingarms are 5.3-6.85 kg for different aluminum versions. The safety factor targeted by most researchers, even though data are limited, has values close to \(N=2\). Braking and cornering forces are accounted for in most of the literature for rear swingarms. The magnitude of these forces is related to tire-ground friction and a simplification called \"friction circle or ellipse\" can be used to understand the maximum forces available for braking and cornering [2]. It assumes that the maximum tire friction force possible in any direction is a constant, which means that a tire can support a specific maximum force either for cornering, or braking, or any combination of steering and braking forces that result to the same maximum resultant force available, which is a simplification of reality. Other research findings exist, where more accurate tire models for combined braking and steering force components can be found, such as the Pajecka Magic formula [19] and BNP-MNC [20]. But according to the above and considering that, in our case, we are exploring the use of a front swingarm, the maximum loading scenario can be defined under emergency braking conditions in a longitudinal driving direction. Basic theory of braking forces calculation can be found in various publications, including related books [21; 22; 23], as well as research focused on evaluation of the effects of braking loads applied on single-sided swingarms [12]. It must be noted though, that when brake forces are calculated, motorcycle tires and especially tire coefficient of friction are important as detailed in Section 2.3. Another important factor, directly linked to braking conditions, is the effect of deceleration.