Topology Optimization for Lightweight Design

Understanding Topology Optimization: A Revolutionary Approach to Engineering Design

In the competitive landscape of modern manufacturing and product development, engineers face an ongoing challenge: creating structures that are simultaneously strong, lightweight, and cost-effective. Topology optimization has emerged as one of the most powerful computational tools available to address this challenge, fundamentally changing how engineers approach structural design across industries ranging from aerospace and automotive to marine equipment and industrial machinery.

For manufacturers and engineering firms throughout Atlantic Canada, topology optimization represents a significant opportunity to enhance product competitiveness while reducing material costs and improving performance. As Nova Scotia's manufacturing sector continues to evolve, embracing advanced design methodologies becomes increasingly essential for maintaining a competitive edge in both domestic and international markets.

Unlike traditional design approaches where engineers refine existing geometries through iterative analysis, topology optimization begins with a defined design space and allows mathematical algorithms to determine the optimal material distribution. The result is often organic, highly efficient structures that would be virtually impossible to conceive through conventional design thinking.

The Science Behind Topology Optimization

At its core, topology optimization is a mathematical method that optimises material layout within a given design space, subject to defined loads, boundary conditions, and constraints. The process divides the design domain into thousands or millions of finite elements, then iteratively determines which elements should contain material and which should remain void.

Key Mathematical Principles

The most common approach to topology optimization employs the Solid Isotropic Material with Penalisation (SIMP) method. This technique assigns a density variable to each element in the design space, ranging from 0 (void) to 1 (solid material). The algorithm then iteratively adjusts these density values to minimise a specified objective function—typically compliance (the inverse of stiffness) or weight—while satisfying all constraints.

The mathematical formulation typically involves:

• Objective Function: Minimisation of structural compliance or total mass

• Design Variables: Element density values (ρ) ranging from 0 to 1

• Constraints: Volume fraction limits, stress constraints, displacement limits, and manufacturing considerations

• Sensitivity Analysis: Calculation of how the objective function changes with respect to each design variable

Modern topology optimization software typically requires between 50 and 200 iterations to converge on an optimal solution, depending on problem complexity and the number of elements in the model. A typical industrial problem might involve design spaces containing 500,000 to 5,000,000 elements, requiring substantial computational resources to solve efficiently.

Density-Based Methods vs. Level-Set Approaches

While SIMP remains the most widely used method, level-set topology optimization has gained popularity for applications requiring smoother boundaries and more precise geometric control. Level-set methods represent structural boundaries as zero-level contours of higher-dimensional functions, producing designs with clearer solid-void interfaces. This approach proves particularly valuable when designing components for traditional manufacturing processes where intermediate densities cannot be physically realised.

Practical Applications Across Industries

Topology optimization has found applications across virtually every sector of engineering, with particularly significant impacts in industries where weight reduction directly translates to improved performance or reduced operating costs.

Aerospace and Defence

The aerospace industry has been at the forefront of topology optimization adoption, driven by the substantial value of weight reduction in aircraft design. Every kilogram removed from an aircraft structure can save approximately 2,500 litres of fuel over a typical 30-year service life. Leading aerospace manufacturers report achieving weight reductions of 20% to 50% on optimised structural components compared to conventionally designed alternatives.

Common aerospace applications include:

• Bracket and fitting designs for airframe structures

• Engine mounting components and nacelle structures

• Satellite structural elements where launch mass directly impacts mission cost

• Unmanned aerial vehicle (UAV) airframes requiring maximum payload capacity

Automotive Engineering

Automotive manufacturers utilise topology optimization to address increasingly stringent fuel efficiency regulations while maintaining or improving crashworthiness. Vehicle lightweighting has become a primary strategy for meeting emissions targets, with topology-optimised components contributing to overall vehicle mass reductions of 100 to 300 kilograms in modern designs.

Automotive applications commonly include suspension components, seat structures, chassis elements, and body-in-white assemblies. The methodology proves particularly valuable for electric vehicle development, where reduced structural weight directly extends battery range.

Marine and Offshore Industries

For Atlantic Canada's significant marine and offshore sector, topology optimization offers substantial benefits for vessel and equipment design. Reduced structural weight in marine applications translates to improved fuel efficiency, increased payload capacity, and enhanced vessel performance. Nova Scotia's shipbuilding and marine equipment manufacturing industries can leverage these techniques to produce more competitive products for both domestic and export markets.

Specific marine applications include:

• Deck equipment and crane structures

• Hull structural elements and bulkhead designs

• Offshore platform equipment and support structures

• Submersible and remotely operated vehicle (ROV) frames

Industrial Machinery and Equipment

Manufacturing equipment designers throughout the Maritime provinces increasingly employ topology optimization to improve machine tool performance. Reduced moving mass in industrial machinery enables higher acceleration rates, improved positioning accuracy, and reduced energy consumption. Machine tool builders report achieving 30% to 40% mass reductions in moving structural elements while maintaining or improving static and dynamic stiffness.

Integration with Additive Manufacturing

The synergy between topology optimization and additive manufacturing (3D printing) has revolutionised the practical implementation of optimised designs. Traditional manufacturing constraints often prevented the realisation of complex topology-optimised geometries, but additive manufacturing removes many of these barriers.

Design Freedom and Complexity

Additive manufacturing processes, particularly metal powder bed fusion technologies such as selective laser melting (SLM) and electron beam melting (EBM), can produce the intricate lattice structures and organic shapes characteristic of topology-optimised designs. This capability enables engineers to fully exploit the weight-saving potential of optimization algorithms without compromising the design to accommodate traditional manufacturing limitations.

However, additive manufacturing introduces its own constraints that must be incorporated into the optimization process:

• Build orientation: Overhanging features beyond 45 degrees typically require support structures

• Minimum feature size: Most metal AM processes require minimum wall thicknesses of 0.4 to 1.0 millimetres

• Surface roughness: As-built surfaces typically exhibit Ra values of 5 to 20 micrometres

• Residual stresses: Thermal gradients during building can induce significant residual stresses requiring post-processing

Hybrid Manufacturing Approaches

Many topology-optimised components benefit from hybrid manufacturing strategies combining additive and subtractive processes. Critical interfaces and precision surfaces may require machining following additive fabrication, while complex internal geometries remain as-built. This approach balances the design freedom of additive manufacturing with the precision and surface quality of traditional machining.

Software Tools and Implementation Strategies

Successful implementation of topology optimization requires appropriate software tools, computational resources, and engineering expertise. Several commercial and open-source platforms offer topology optimization capabilities with varying levels of sophistication and integration.

Commercial Software Platforms

Leading commercial topology optimization packages include:

• Altair OptiStruct: Industry-leading solution with extensive manufacturing constraint options

• ANSYS Topology Optimization: Integrated within the ANSYS Mechanical environment

• Siemens NX Topology Optimization: Tightly integrated with CAD and simulation workflows

• TOSCA Structure: Dassault Systèmes solution integrated with Abaqus and SIMULIA products

• SolidWorks Simulation: Accessible topology optimization for mainstream design engineers

Selection of appropriate software depends on existing CAD/CAE infrastructure, specific application requirements, and available engineering expertise. Integration with existing design workflows proves critical for efficient implementation.

Computational Requirements

Topology optimization problems are computationally intensive, with solution times ranging from minutes for simple 2D problems to days for complex 3D analyses with multiple load cases and constraints. Modern workstations equipped with multi-core processors (16 to 64 cores) and 64 to 256 gigabytes of RAM typically provide adequate performance for most industrial applications. Cloud computing resources offer scalable alternatives for occasional users or particularly demanding analyses.

Best Practices for Successful Implementation

Achieving meaningful results from topology optimization requires careful attention to problem setup, constraint definition, and post-processing of results.

Problem Definition

Accurate definition of the design problem fundamentally determines the quality of optimization results. Engineers must carefully consider:

• Design space definition: The region where material distribution will be optimised

• Non-design regions: Areas that must remain solid for functional requirements (mounting interfaces, bearing surfaces)

• Load cases: All relevant loading conditions the structure must withstand

• Boundary conditions: Accurate representation of structural supports and constraints

• Material properties: Appropriate material models for the intended manufacturing process

Constraint Selection

Proper constraint selection balances design freedom with practical manufacturing and performance requirements. Common constraints include volume fraction limits (typically 10% to 40% of the original design space), stress limits based on material allowables with appropriate safety factors, displacement limits for stiffness-critical applications, and manufacturing constraints such as minimum member size and draw direction.

Post-Processing and Interpretation

Raw topology optimization results require interpretation and refinement before implementation. The optimised geometry typically requires smoothing, symmetry enforcement if applicable, and adaptation to manufacturing requirements. Engineers must verify that the final design satisfies all performance requirements through detailed structural analysis, as the optimization process employs simplified models that may not capture all relevant physical phenomena.

Economic Benefits and Return on Investment

Investment in topology optimization capabilities delivers measurable returns through multiple mechanisms. Material cost savings of 20% to 50% on optimised components directly impact manufacturing costs, while weight reductions in transportation applications yield ongoing operational savings through improved fuel efficiency.

For engineering firms and manufacturers in Nova Scotia and throughout Atlantic Canada, topology optimization capabilities represent a competitive differentiator in increasingly global markets. The ability to deliver lightweight, high-performance designs enables local manufacturers to compete effectively against lower-cost international competitors by offering superior technical solutions.

Development time reductions of 30% to 50% have been reported for complex structural design projects, as topology optimization rapidly explores design alternatives that would require weeks of manual iteration using conventional approaches. This acceleration proves particularly valuable in competitive bidding situations where rapid response to customer requirements influences contract awards.

Partner with Sangster Engineering Ltd. for Advanced Design Solutions

Implementing topology optimization effectively requires a combination of sophisticated software tools, computational resources, and experienced engineering judgement. Sangster Engineering Ltd. brings decades of engineering expertise to help clients throughout Nova Scotia, Atlantic Canada, and beyond leverage advanced design methodologies for competitive advantage.

Our team combines deep understanding of structural mechanics with practical manufacturing knowledge to deliver topology-optimised designs that are not only theoretically optimal but also practically realisable. Whether you are developing new products, seeking to reduce costs on existing designs, or exploring advanced manufacturing opportunities, we provide the technical expertise and analytical capabilities to achieve your objectives.

Contact Sangster Engineering Ltd. in Amherst, Nova Scotia, to discuss how topology optimization and other advanced analysis techniques can benefit your next project. Our commitment to engineering excellence and client success has made us a trusted partner for organisations across the Maritime provinces and beyond.

Partner with Sangster Engineering

At Sangster Engineering Ltd. in Amherst, Nova Scotia, we bring decades of engineering experience to every project. Serving clients across Atlantic Canada and beyond.

Contact us today to discuss your engineering needs.