ACCIDENT SIMULATIONS OF A NOVEL RESTRAINT SAFETY CONCEPT FOR MOTOR- CYCLISTS Steffen Maier, Jörg Fehr Institute of Engineering and Computational Mechanics, University of Stuttgart Germany Paper Number 23-0189 ABSTRACT Except for personal protective equipment, riders of powered two-wheelers are currently unprotected when impacting into an accident opponent. This work investigates a motorcycle safety concept that proposes a combination of thigh seat belts, airbags, and leg impact protectors. It gives a virtual prediction of the accident behavior using finite element models of the motorcycle with passive safety systems, an accident opponent, and an anthropometric test device as a rider surrogate in recommended frequent accident scenarios. It shows a meaningful graphical description of the functional and causal principles of a powered two-wheeler rider restraint and a quantified performance evaluation of the concept. The combination of several passive safety systems has shown to be promising in positively influencing accident behavior and mitigating consequences. INTRODUCTION From economic and environmental perspectives, powered two-wheelers (PTWs) are an efficient mode of transportation. Because of high traffic volume, many cities have already reached their capacity limits at peak traffic times. A shift to smaller vehicles can provide much-needed relief. A case study of the Leuven-Brussels motorway journey [1] examines the impact of a modal shift in which 10 % of cars are replaced by PTWs. The traffic flow model simulation states that traffic loss hours decrease by 63 % from 1925 hours in a reference scenario to only 706 hours lost. Also, regardless of the type of drive, PTWs consume fewer resources in production and have a lower energy consumption and use less space than cars. Considering the average occupancy (e-scooter: 1.1 persons vs., e.g., a mid class passenger car: 1.34 persons) in an evaluation of different transportation modes for urban areas [2], e-scooters perform among the best regarding the energy demand in use. They are more efficient than other electric vehicles, buses, and the tram; only bicycles and e-bicycles are more efficient than electric PTWs. However, their poor passive safety is their decisive disadvantage at considerable social costs. A comparison of the fatality risks of various modes of transportation (cars & light trucks, pedestrians & bicycles, motorcycles, large trucks, buses, maritime, aviation, railroads, pipeline) in the US for 2000- 2009 [3] shows that riding a motorcycle is by far the most dangerous. Riding a motorcycle accounts for 212 fatalities per billion passenger miles; driving or being a passenger in a car or light truck only accounts for 7.28 fatalities per billion miles traveled. This is because motorcycles do not provide any- where near the same level of crashworthiness and rider protection as automobiles do for their occupants. A car is much more stable and easier to see. In the event of an accident, a car has the advantage of significantly more weight and volume. It fully encloses the occupants in a safety cell and provides passive safety features such as seat belts and airbags. In contrast, the safety equipment of most mo- torcyclists is currently limited to personal-worn protective equipment. The current safety strategy of conventional motorcycles does not go beyond the intention or, even more so, hope that the vehicle user will be able to get as little as possible entangledwith themotorcycle andwill be thrown off quickly instead. There are two main approaches to passive safety in motorcycle literature [4]. In the first principle, the rider is restraint to the motorcycle. In a collision, kinetic energy from the motorcycle is converted into Maier 1 deformation work. The rider restraints, e.g., belts or airbags, aim to prevent direct contact between the motorcyclist and an accident opponent up to a certain collision speed. Production motorcycles that aim for that principle are rare. The Honda Goldwing is a large tourer equipped with a frontal airbag [5, 6, 7]. The BMWC1 is a city scooter with a rollover structure and belt restraint for an upright seated rider [8, 9]. In the second principle, the rider must be separated from the motorcycle as soon as possible, and a direct impact must be avoided. Here, the rider mustn’t get tangled up in parts of the motorcycle. In the best case, a flyover of the motorcyclist over the accident opponent is initiated. The principle aims that the injuries of a flyover should be less than those of a direct impact. Most motorcycles aim for this safety principle. Several types of rider kinematics have been identified for impacts with these conventional motorcycles, see e.g. [10, 11], for experiments including a pillion passenger [12]. The observed patterns can be divided, as shown by [13], into one of the types illustrated in Figure 1: (a) a direct impact, (b) a rollover, or (c) a flyover of the rider. Before impact, this depends on the points of contact at the collision opponents; during the collision phase, it depends on the vehicle geometries and the structural properties. In a direct impact, the rider is decelerated the most; hence the resulting immediate energy input into the rider is the highest. For a rollover, the energy input is lower, and for a flyover even lower. In the case of a rollover or flyover, the rider detaches from the motorcycle, which remains the decisive safety principle of today’s motorized two-wheelers. This assumes that injuries in the subsequent so-called secondary accident phase will be less than in a direct car impact. The chances of being injured less severely or not at all are promising only if the rider is wearing effective personal protective equipment and slides freely to the final position after impact without coming into contact with other vehicles or fixed objects. (a) direct impact high energy transfer (b) rollover with medium energy transfer (c) flyover with low energy transfer Figure 1: Types of collisions of a conventional motorcycle and rider against an opposing vehicle. The safe motorcycle studied here aims at the first principle. It consists of a newly designed motorcycle frame and body, seat belts, multiple airbags, foam leg impact protectors, and a side impact structure; see full FE model in Figure 2. The concept, initially described in [14], envisages that in the event of an impact, the two belts around the thighs restrain the rider to the motorcycle. The surrounding airbags then decelerate the upper body rotation in a controlled manner and protect the rider from hard contact with an opposing vehicle, the road, or road-side structures. The foam impact protectors absorb the impact of the legs on the motorcycle cockpit and the side impact structure protects the lower extremities laterally. The concept’s idea is to preserve the open design and superior all-around visibility and maneuverability of a two-wheeler without any rollover structure. The goal is to supersede a motorcycle rider’s safety clothing and helmet entirely in the future and, therefore, significantly increase the suitability of motorcycles as commuter vehicles and/or shared mobility solutions. Maier 2 side airbag mirror airbag front airbag thigh belts leg impact receding side impact structure windshield protectors Figure 2: FE motorcycle with restraint safety concept and Hybrid III 50th ATD as rider surrogate. This paper presents the tools and methods to design an optimal and robust novel safety concept for mo- torcycles. The safety concept combines well-established safety strategies of occupant protection onto a motorcycle to minimize the intrinsic unpredictability of PTW crashes. The novelty of this work is the in- vestigation of the PTW safety concept in a full FE approach, as part of a modeling and simulation strategy with different levels of model fidelity. It aims for a meaningful description of the operating principles and their influence on the accident behavior in comparison to a conventional PTWbased on the virtualmodels. MODELING The work presented here is part of a a multi-stage, multi-model approach with varying degrees of model fidelity, outlined in Figure 3. stage II: coupled FE/MB model stage III: full FE model modeling stage I: combinedMB/FEmodel Ls-DynaMadymo simulation ESV 2023[15, 16][14] Figure 3: Modeling and simulation strategy. Maier 3 81 parts 323,000 nodes 60 beam elements 243,000 shell elements 135,000 solid elements 12 joint connections 25 extra node set connections 67 nodal rigid body connections Figure 4: Discretization of the FE motorcycle model, shown as wireframe elements. The modeling and simulation strategy consists of three stages (I) to (III): (I) In the MADYMO software environment1, the motorcycle, airbags, belts, rider surrogate, and accident opponent are modeled in a combined multibody and FE approach, introduced in [14]. Vehicle deformation and contact characteris- tics, as well as an effectiveness assessment of the passive safety systems are based on fitted simulation models of full-scale crash tests of conventional motorcycles. (II) An equivalent FE model of the rider interaction surfaces, coupled to accident trajectories from MB simulations, includes the leg impact pro- tectors in the LS-DYNA software environment2, introduced in [15, 16] also used in [17]. (III) Simulations of a full FE approach in LS-DYNA that also includes the motorcycle’s structurally relevant components as deformable parts. In this work, the proposed motorcycle is investigated in the shown full FE model approach (stage III), shown in Figure 4. The model aims to represent the interaction with the crash opponent, structural loading and deformation, and energy absorption of the motorcycle structure. As a result, its focus is on representing the crash- relevant structural components, which are the front wheel, front tire, and front suspension assembly. Components such as the drivetrain are modeled as rigid parts because they are assumed not to deform because they are very stiff or outside of the crash deformation. As a unique feature of the proposed mo- torcycle structure a foam crash box in the cockpit nose aims to control the energy transfer. This prevents a rollover in a frontal impact. The elevated side impact structures protect the lower extremities laterally. In total, the model consists of 81 parts from 378,000 elements with 323,000 nodes. The suspension is modeled with eight kinematic joints; front wheel rotation (2), telescopic front fork suspension (2), rear-wheel rotation (2), front fork steering, and rear swing arm rotation. The other kinematic joints are for the lids of the compartments behind which the airbags are located. Recent other detailed FE models of PTWs for crash investigations are [7] (a large tourer), [18] (a three- wheeled scooter), [19] (a sport bike), and [20] (a sport tourer). 1SIEMENS Simcenter Madymo (version 2021.1 SMP): https://www.plm.automation.siemens.com/global/en/ products/simcenter/madymo.html 2Ansys LS-DYNA (version R9.3.1 MPP): https://www.ansys.com/products/structures/ansys-ls-dyna Maier 4 https://www.plm.automation.siemens.com/global/en/products/simcenter/madymo.html https://www.plm.automation.siemens.com/global/en/products/simcenter/madymo.html https://www.ansys.com/products/structures/ansys-ls-dyna Impact configurations As a set of representative impact scenarios, accident configurations from ISO1323 [21] are used. The standard isolates seven representative impact configurations 1 to 7 , shown in Figure 5. The set in- cludes collisions between a motorcycle and a passenger car, with the motorcycle and car, either stationary or moving forward up to a speed of ≈48 km/h (13.4 m/s). The contact points on the motorcycle and car are at the front and side, respectively. There are no rear contacts included (either at the car or at motorcycle). The standard defines the opposing vehicle as a four-door saloon with a mass of 1,238- 1,450 kg and an overall height of 137-147 cm. The set does not include scenarios with roadside barriers. As the accident opponent, the FE model of a 2001 Ford Taurus [22] is used. The model, developed and validated by the National Crash Analysis Center (NCAC), is publicly available in the NHTSA ve- hicle database [23]. With an overall height of 147 cm and a mass of 1477 kg the four-door passenger sedan complies with [24] specifications for the opposing vehicle height but slightly exceeds vehicle mass. 143-9.8/0 114-6.7/13.4 413-6.7/13.4 412-6.7/13.4 5 6 7 45◦ 45◦ 90◦ 90◦ 135◦ 135◦ 45◦ 5 cm w/2 l/2 motorcycle speed in m/s car speed in m/s geometry code 1 2 3 4 414-6.7/13.4 225-0/13.4 413-0/13.4 w l Figure 5: Representative set of impact configurations according to [21]. Injury criteria For passenger vehicle occupant protection, there are national and international regulations, such as the ECE regulations by theUnitedNations Economic Commission for Europe (UNECE) or FederalMotor Vehicle Safety Standards (FMVSS) for the US that specifies injury criteria and respective maximal values for specific load cases. Also, consumer ratings such as the New Car Assessment Programs for the United States (US NCAP) and the European Union (Euro NCAP) provide constantly updated biomechanical criteria from the latest scientific findings of occupant protection. To the best of the authors’ knowledge, for the passive safety of motorcyclists, such governmental regulations or consumer ratings currently do not exist. The most recent version of ISO 13232 recommends only a very limited set of criteria. The work presented here aims to assess many potential injury mechanisms for the whole body. The selection of injury criteria considered are summarized in Table 1. It is based on a comprehensive set of injury criteria and corresponding biomechanical limits for motorcyclists from an extensive literature review by [25]. This selection is extended to include the GAMBIT, which is recommended in the international standard [26], as well as the BrIC and the Nij criterium. For femur criteria, stricter thresholds from ECE-R 94 [27] are used. Maier 5 body region injury criterion limit (Hyb III 50th) ref. head resultant acceleration atint = max t1 ( min t1≤t≤t1+tint ares(t) ) 80 g for tint = 3ms [27] head injury criterion HIC(t2−t1) = max t1,t2 { (t2 − t1) [ 1 t2 − t1 ∫ t2 t1 ares(t)dt ]2.5 } with ares(t) in g and t in s 1000 for t2−t1≤36ms [28, 29] generalized accelera- tion model for brain injury threshold GAMBIT= [( ares(t) aC )2.5 + ( Üϕres(t) ÜϕC )2.5 ] 1 2.5 with aC = 250 g and ÜϕC = 25 krad/s2 1 [30] brain injury criterion BrIC(CSDM) =√( max |ωx(t)| ωxC )2 + (max |ωy(t)| ωyC )2 + ( max |ωz(t)| ωzC )2 with ωxC = 66.2,ωyC = 59.1,ωzC = 44.25 rad/s 1 [31] neck tensile force Fz,tens,tint = max t1 ( min t1≤t≤t1+tint Fz(t) ) 3.3 kN for tint = 1ms 1.1 kN for tint = 45ms [32, 29] compression force Fz,compr,tint = min t1 ( min t1≤t≤t1+tint Fz(t) ) 4 kN for tint = 1ms 1.1 kN for tint = 45ms shear force Fxy,tint =max t1 ( min t1≤t≤t1+tint √ Fx(t)2+Fy(t)2 ) 3.1 kN for tint = 1ms 1.1 kN for tint = 45ms forward moment My,fwd,max = min My(t) 190Nm rearward moment My,rwd,max = max My(t) 57Nm neck injury criterion Nijmax = max (����Fz(t) Fint ���� + ���� My(t) Mint ����) with Fint,C/T=6160/6806N, Mint,F/E=310/135Nm 1 [28, 33, 29] thorax resultant acceleration atint = max t1 ( min t1≤t≤t1+tint ares(t) ) 60 g for tint = 3ms [29] thorax compression ThCC = max s(t) 50mm [27] viscous criterion VCmax = max (V (t) · C (t)) 1m/s [34, 27] pelvis resultant acceleration atint = max t1 ( min t1≤t≤t1+tint ares(t) ) 60 g for tint = 3ms [25] femur axial force |Fz |max = max |Fz(t)| 9.07 kN [27] tibia tibia index TImax=max ©­­« ������� √ Mx(t)2+My(t)2 (MC)res �������+ ���� Fz(t) (FC)z ����ª®®¬ with (MC)res=225 Nm and (FC)z=35.9 kN 1.3 [35, 27] Table 1: Selected injury criteria with biomechanical limits for the Hybrid III 50th ATD. Maier 6 ACCIDENT SIMULATION Conventional Motorcycle For comparison, a full laboratory crash test of a conventional motorcycle against a passenger car is used. It is an impact according to ISO 12323 7 with a helmeted Hybrid III 50th anthropometric test device (ATD) as part of investigations of [25], to which data we have access to. The laboratory tests are documented with a test protocol and high-speed video footage, a 15-channel sensor data set of the ATD, and accelerometers at multiple points on the motorcycle. The test is then simulated with the MBS approach, see [14], shown in Figure 6. 0 ms 50 ms 150 ms 100 ms 200 ms 250 ms 400 ms 300 ms Figure 6: MB simulation (stage I) of full-scale crash test SH01.01 [25] of a conventional motorcy- cle Yamaha FZS 600 Fazer and a helmeted Hybrid III 50th against a VW Golf II in scenario 7 . Figure 7 illustrates the resulting deceleration from the MB simulation of the motorcycle, the opposing vehicle, and the main body parts of the rider for the conventional motorcycle impact by plotting the velocities. The velocities are filtered with a CFC (channel frequency class) filter, see [36]. The impact causes the motorcycle to decelerate relatively uniformly from the initial speed, initiating a forward rota- tion of the PTW. After the rider is not decelerated until about 40 ms, he is abruptly decelerated by the impact of the pelvis on the tank and the helmeted head on the car. According to the classification in Figure 1, the collision corresponds to a direct impact with a high energy transfer. A classification into accident phases in Figure 8 reduces the accident occurrence to a chronology of significant events. It illustrates long dead times of the rider’s head, pelvis, and legs. Tank impact and hel- meted car impact are concentrated short-time events. These lead, i.a., to a high deceleration of the head (a3ms), a very high neck axial compression (Fz,compr,1ms) and shear loading (Fxy45ms), and a high rear- ward (extension) moment (My,rwd,max), see the evaluation of the injuria criteria in Figure 15. The greyed fields ("N/A") are injury criteria that could not be determined with the ATD sensor channels of SH 01.01. Maier 7 0 50 100 150 0 5 10 15 accident contact relative velocity of motorcycle to car = 0 m/s tank impact helmeted car impact time in ms ve lo ci ty in m /s head thorax pelvis motorcycle car rider (CFC180) vehicles (CFC60) vx vres Figure 7: Velocities of conventional motorcycle and motorcyclist’s main body parts relative to car’s velocity in a frontal collision according to scenario 7 (MB simulation shown in Figure 6). time in ms 0 50 100 150 motorcycle rider accident contact relative velocity of motorcycle to car = 0 forward rotation deceleration through deformation legs dead time pelvis dead time tank impact thorso&head dead time helmeted car impact Figure 8: Schematic chronology of conventional motorcycle and rider behaviour in a frontal collision according to configuration 7 (MB simulation of Figure 6). Motorcycle with Restraint System To analyze the safe motorcycle with rider restraint, all seven ISO 13232 scenarios are simulated using the full FE model; see overview in Figure 9. It shows the accident kinematics up to 500 ms each, referred to as the primary impact phase. For the impacts shown, the effect of the safety system can be summarized as follows: The belts restrain the rider to the motorcycle, with the belt load-limiting devices limiting the pelvis accelerations. The belt restraint establishes a pivot point at the pelvis to guide the upper body in forward and sideward rotations and to keep the riders’ bodies within the range of the airbags and within the leg protectors and side-impact protection structure. The surrounding airbags decelerate the upper body motion and prevent impact against hard structures, such as the uncushioned motorcycle cockpit surfaces and the accident opponent. The motorcycle cockpit and the accident opponent are reaction surfaces for the airbags. Maier 8 0ms 50ms 100ms 200ms 300ms 400ms 500ms configuration 4 0ms 50ms 100ms 200ms 300ms 400ms 500ms configuration 3 0ms 50ms 100ms 200ms 300ms 400ms 500ms configuration 2 0ms 50ms 100ms 200ms 300ms 400ms 500ms configuration 1 solver run times: 59.9 h/16 CPUs/MPP/single precision/Ls-DYNA R9.3.1 with AMD Ryzen 9 5950X 16-Core CPU@3.4GHz Maier 9 0ms 50ms 100ms 200ms 300ms 400ms 500ms configuration 7 0ms 50ms 100ms 200ms 300ms 400ms 500ms configuration 5 0ms 50ms 100ms 200ms 300ms 400ms 500ms configuration 6 Figure 9: Primary impact response of motorcycle with restraint system in full FE simulations of ISO 13232 configurations with a non-helmeted Hyb III 50th up to 500 ms. Scenarios 1 – 3 , 5 , and 7 are impacts where the motorcycle is particularly violently de- or accel- erated. In scenario 4 , the motorcycle bounces off at a shallow angle without losing much speed. In near miss scenario 6 , the motorcycle grazes the car. The latter two scenarios are particulary interesting for analyzing the secondary accident behavior because much residual energy remains in the motorcycle and the passenger. This also applies to scenarios 1 and 2 because the car accelerates the motorcycle through the collision. The heat map in Figure 10 illustrates an evaluation of the biomechanical injury criteria. The selected criteria from Table 1 are normalized to their respective biomechanical limit for the Hybrid III 50th ATD and are color-coded to indicate the severity of the body loads. Overall, only the tibia index (TI) from tibia forces and moments, the brain injury criterion (BrIC) based on head angular velocity, and the thorax acceleration a3ms criterion exceed their biomechanical limits in some scenarios. Simulations of the safety Maier 10 head neck thorax pelvis tibia femur 0.38 0.21 0.26 0.13 0.12 0 0.33 0.59 0.49 0.73 0.39 0.52 0.13 0.69 0.21 0.23 0.43 0.19 0.26 0.08 0.28 0.66 0.64 0.21 0.87 0.52 0.37 0.35 0.21 0.47 0.12 0.54 0.97 0.35 0.06 0.24 0.23 0.01 0.54 0.07 0.04 0.08 0.07 0.07 0.04 0.02 0 0 0.02 0.02 0.04 0.01 0 0.15 0.15 0.33 0.12 0.23 0.08 0.3 0.24 0.17 0.12 0.13 0.08 0.14 0.09 0 0.02 0.03 0.04 0.01 0 0 0 0.4 0.12 0.19 0.06 0.11 0 0.32 0.24 0.24 0.13 0.31 0.08 0.37 0.36 0.74 0.44 0.74 0.12 0.72 0.07 0.39 0.5 0.19 0.29 0.06 0.34 0.01 0.14 0.35 0.04 0.11 0.01 0.09 0.49 0.93 0.7 0.36 0.43 0.29 0.62 0.24 0.23 0.25 0.16 0.19 0.13 0.23 0.69 0.79 0.68 0.47 0.53 0.49 1.06 1.08 1.14 1.24 1.02 0 0.2 0.4 0.6 0.8 1 1.2 1 2 3 4 5 6 7 co nfi gu ra tio n Figure 10: Injury criteria relative to biomechanical limits for primary impact up to 500 ms shown in Figure 9. concept with HBMs [17] also show high BrIC values, exceeding the recommended threshold. The high thorax a3ms values in 3 are due to the arms getting caught in the cockpit fairing and being mechanically locked which transmits a shock trough the rigid arm joints into the torso. Apart from these, the highest values are the head and pelvis a3ms acceleration and neck axial tension. These are concept-related mainly dependent on the belt restraint’s load limit, which is a tradeoff between the feasible frontal displacement of the rider and tolerable body loads. A lower belt load limit reduces body loads from the rider restraint but also increases the risk of the head hitting the accident opponent. The leg protectors and side impact protection keep femur axial loading low. vMoto =13.4 m/s 0 5 10 15 20 25 30 0 50 100 150 200 0 ms 10 ms 20 ms d in cm rig id w al lf or ce in kN COGBody d rigid wall rigid floor front fork collapses front tire compressed front rim collapses CFC 180 60 ms 40 ms 80 ms 30 ms Figure 11: Frontal deformation characteristics of motorcycle. Maier 11 x z front wheel vs. door sill cockpit vs. door 65 ms Figure 12: Motorcycle to car structural interaction and intrusion behaviour in full FE simulation (right airbags are not displayed). Unlike the conventional motorcycle collision, the proposed motorcycle does not roll over about its trans- verse axis during a frontal impact. The voluminous cockpit and the resulting high contact point prevent pitching. Figure 11 illustrates the designed frontal deformation characteristics in impact with a rigid wall. It identifies subsequent phases of deformation: (i) compression of the front tire, (ii) collapse of the front rim, and (iii) collapse of the front fork. The area enclosed corresponds to the dissipated energy. Figure 12 reveals the structural interaction and intrusion of the motorcycle against the opposing vehicle. The motorcycle’s front wheel collides with the sill of the car, and the motorcycle cockpit deforms the car door inward. Figure 13 shows equivalent to Figure 7 the deceleration based on the velocities of the motorcycle and the main body parts of the rider in a frontal collision (scenario 7 ). It shows quite descriptive the benefits of the safety system concept. The belts interact early leading to a relatively continuous deceleration by restraining the pelvis. After about 80 ms, the front airbag decelerates the upper body rotation. Overall the main body parts are decelerated continuously over an increased time period, compared to the short-term impacts of the conventional motorcycle. Plotting a schematic chronology results in Figure 14. Extended by a safety systems layer, it shows the timing and operating phases of the seat belt and airbag systems as well as the leg impact protectors. 0 50 100 150 0 5 10 15 accident contact accident detection relative velocity of motorcycle to car = 0 m/s relative velocity of rider to motorcycle ≈ 0 m/s front airbag deceleration time in ms ve lo ci ty in m /s thigh belt head thorax pelvis motorcycle car rider (CFC180) vehicles (CFC60) restraint Figure 13: Velocities of motorcycle with restraint safety systems and motorcyclist’s main body parts in a frontal collision according to configuration 7 (Full FE simulation shown in Figure 9). Maier 12 time in ms 0 50 100 150 motorcycle safety systems rider accident contact accident detection relative velocity of motorcycle to car = 0 relative velocity rider to motorcycle ≈ 0 deceleration through deformation leg protectors delayed & distributed energy transfer + energy dissipation thigh belts pretensioning load limiting rigid restraint front airbag inflation retention deflation legs dead time leg protector deceleration pelvis dead time thigh belt restraint thorso&head dead time front airbag deceleration Figure 14: Schematic chronology of motorcycle with restraint safety systems and rider behaviour in a frontal collision according to configuration 7 (Full FE simulation of Figure 9). Figure 15 is a comparison of the resulting injury criteria of the conventional motorcycle vs. the motor- cycle with the rider restraint. The crash test criteria of the conventional motorcycle are based on the experimental sensor data of the laboratory test; for the motorcycle with rider restraint, they are from the full FE simulation. Change for the better or the worse is highlighted by green and red arrows. Overall, the number of critical values is reduced. Whereby with the current parameters fot the design varibles lead safety-concept related to higher loads for neck axial tension and pelvis and thorax acceleration. SH01.01 motorcycle with rider restraint 0.33 0.69 0.28 0.87 0.54 0.54 0.02 0 0.3 0.09 0 0 0.37 0.72 0.34 0.09 0.62 0.23 0.49 0.4 0.97 0.21 0.37 0.23 0.67 0.81 0.12 0.88 0.31 0.04 0 0.571.25 1.7 1.02 0 0.5 1 N/A head neck thorax pelvis tibia femur Figure 15: Injury criteria relative to respective biomechanical limit for conventional motorcycle (top; experimental data of SH01.01) and motorcycle with rider restraint (bottom; full FE simulation). Maier 13 DISCUSSION The work investigates the primary impact behavior of a recommended set of impact scenarios involving PTWs. The motorcycle’s safety concept enables a guided rider trajectory and controlled energy dis- sipation through rider restraint with continuous deceleration during a motorcycle-to-car impact. With few exceptions, recommended injury criteria and respective biomechanical limits indicate tolerable rider loading. Some values for BrIC, TI, and thorax a3ms are not within the recommended biomechanical limits. A comparison with a conventional motorcycle shows the advantages of controlled and contin- uous load application onto the body of the rider. The consequences of an accident depend less on the randomness and unpredictability of a conventional accident with multiple possible trajectories than on the design variables of the safety system. The secondary impact behavior, impacts against other accident opponents, e.g., roadside barriers, and solo accident behavior, have not yet been considered. These types have prevalently long accident histo- ries. The use of full FEmodels with long computation times is challenging since they are computationally costly, even when complex structural interactions with large deformations occur less in such secondary accident phases and solo accidents. Here, future use of hybrid variants that combine the structural impact response of a full FEmodel and the large rigid bodymotions of anMBmodel seems particularly desirable. CONCLUSIONS This work contains • a virtual prediction of the accident behavior of a motorcycle with passive safety systems, • a meaningful graphical description of the functional and causal principles of a PTW rider restraint, • and a quantified performance evaluation of the concept. 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