Senior Mechanical Simulation Engineer

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We are seeking an experienced and motivated Senior Mechanical Simulation Engineer to lead the design, simulation, and optimization of precision opto‑mechanical systems and advanced substrate structures critical to the performance of Flux's Optical Tensor Processing Units (OTPUs).

This role is ideal for an engineer with a strong background in mechanical design, finite element analysis (FEA), substrate stack‑up design, and thermo‑mechanical reliability. You will drive simulation‑led development of precision assemblies and materials that meet demanding thermal, mechanical, and reliability targets.

You will collaborate closely with optical, electrical, and materials teams to ensure designs deliver outstanding stability, thermal performance, and structural integrity during manufacturing and operation.

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• Design and develop mechanical assemblies such as substrates for high‑performance optical and computing systems.
  
• Define and optimize substrate stack‑ups, balancing mechanical stability, warpage control, thermal dissipation, and integration requirements.
  
• Conduct finite element analyses (FEA) to evaluate stress, strain, warpage, and finite element analyses (FEA)
  
• Execute thermo‑mechanical simulations to assess material deformation, stress evolution, and structural response under varying loads and temperatures, including effects during assembly, solder reflow, and system‑level integration.
  
• Perform ageing and life‑cycle simulations to model long‑term material degradation, creep, fatigue, and stress relaxation over extended operational lifetimes.
  
• Lead material selection and evaluation to meet mechanical, thermal, and reliability needs - balancing CTE compatibility, stiffness, and thermal conductivity with manufacturability and cost.
  
• Apply expertise in substrate materials (ABF, BT, ceramics, and organics) to achieve optimized mechanical and thermal performance.
  
• Develop and correlate simulation models with empirical testing (e.g., thermal cycling, vibration, and temperature‑humidity bias) to validate predictions and improve design accuracy.
  
• Collaborate across disciplines to co‑optimize substrate stack‑ups, thermal interfaces, and mechanical assemblies for stability and manufacturability.
  
• Interface with vendors and manufacturing partners to define mechanical specifications, tolerances, and material standards.
  
• Automate and standardise simulation workflows using ANSYS, Abaqus, or COMSOL, ensuring consistency and efficiency.
  
• Document simulation methodologies, assumptions, and recommendations for design iteration and technical communication.
  

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• 7+ years of experience in mechanical design and simulation, ideally within opto‑mechanical systems, electronics enclosures, or advanced materials applications.
  
• Proven expertise in substrate stack‑up design - understanding of material interactions, thermal mismatch, and mechanical coupling.
  
• Demonstrated proficiency in FEA and thermo‑mechanical modelling for complex 3D structures.
  
• Experience performing ageing simulations to assess creep, fatigue, and time‑dependent material behaviour.
  
• Strong understanding of material properties – including CTE, elastic modulus, Poisson’s ratio, and thermal conductivity – and their impact on performance and reliability.
  
• Proficiency in SolidWorks for mechanical modelling and ANSYS, Abaqus, or COMSOL for multiphysics simulation.
  
• Experience with warpage mitigation, thermal management, and assembly‑level stress analysis.
  
• Familiarity with DFM/DFR principles, reliability testing, and integration process constraints.
  
• Strong analytical, problem‑solving, and communication skills with the ability to translate simulation data into design improvements.
  
• Bachelor’s degree in Mechanical Engineering, Materials Science, or related field; Master’s or PhD preferred.
  

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• Competitive salary ranging from £95,000 - £132,000 +, depending on experience.
  

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• Competitive salary and stock options, you're not just part of the journey, you will own a piece of it.
  
• Work from our HQ in King's Cross, right in the middle of London's buzzing AI scene.
  
• Live within 45 minutes of the office? Perfect. Live within 20 minutes? We'll add an extra £24,000 a year to your salary.
  
• We offer visa sponsorship and full relocation support (UK and abroad), through a dedicated third‑party provider who are on hand to make your move to London as seamless as possible.
  
• Full BUPA healthcare and dental cover, medical history disregarded.
  
• High‑spec tech for everyone – M4 Macs as standard, M4 Pros for Engineers.
  
• Sony noise‑cancelling headphones and ergonomic setups to keep you comfortable and focused.
  
• Personal company card to spend on tools that help you do your job – like ChatGPT Pro or anything else that boosts your workflow.
  
• Healthy, chef‑cooked dinners in the office every night, with something for every diet and tastebud.
  
• Monthly off‑site team socials.
  
• 25 days of paid holiday, plus all the UK bank holidays.
  
• Access to our in‑house 3D printer for personal or work projects.
  
• Cycle 2 work scheme.
  
• Need a caffeine fix? We've got you covered with a tab at our favourite local coffee shop.
  
• We offer a pension plan and salary sacrifice options.
  

We do not accept unsolicited CVs from recruitment agencies, will not be liable for any fees, and prohibit unauthorised use of our company name in recruitment activities.