Safety engineering analysis is a mandatory stage in the design of critical embedded automotive systems. The derivation of safety requirements and their verification require establishing traceability links between requirements and the different artifacts involved in the design flow. This paper presents the different steps of a method for expressing non functional requirements (safety, timing, hardware, performance) and ensuring their validation and their traceability over a design flow for automotive system design based on the conjoint use of EAST-ADL2 and MARTE languages and supported in an Eclipse platform. A specific meta-model for requirements modeling and traceability is used. The methodology is illustrated on an industrial knock-control system characterized by strict safety and temporal constraints