Langford Analytic · Knowledge Base
Blast & Explosive Loading
Structural response to externally defined blast pressure environments — from load definition, pressure histories and dynamic response through component/system behaviour, nonlinear SDOF, explicit FEA, progressive damage, residual capacity, verification and substantiation. The emphasis is defensive structural assessment: the explosive source and hazard definition remain controlled upstream inputs, while this chapter addresses how the resulting pressure environment is translated into verified structural response, acceptance and post-event integrity.
Blast Analysis Fundamentals
Blast Structural Analysis FundamentalsHow short-duration pressure loading produces structural response governed by inertia, duration, ductility, load path and failure mode — and how blast analysis differs from ordinary static pressure assessment.Defining Externally Specified Blast Load CasesHow to convert a supplied blast hazard definition into controlled structural load cases without silently changing the source assumptions, conservatism or spatial and temporal character of the pressure field.
Load Definition & Pressure Histories
Pressure–Time Histories, Peak Pressure & ImpulseHow the shape, peak, duration and impulse of a prescribed blast pressure history influence structural response, and how to simplify or resample a pulse without losing the physics that controls the decision.Reflected Pressure, Surface Orientation & ClearingHow a prescribed blast field interacts with structural surface orientation, reflection and finite-surface clearing, and why the pressure history must be matched to the actual face being analysed.Spatially Varying, Internal & Confined Pressure LoadingHow to model prescribed non-uniform and internal blast pressure fields, including arrival-time variation, enclosure pressurisation and vent-dependent structural loading, without reducing them to an unrealistic uniform pulse.
Structural Dynamics & Response
Dynamic Response Regimes & SDOF IdealisationHow blast-loaded components can be reduced to equivalent single-degree-of-freedom systems, when that idealisation is useful, and where it breaks down because of local modes, support flexibility or evolving failure.Stress Waves, Inertia & Local-to-Global Blast ResponseHow inertia and stress-wave propagation create different response timescales in blast-loaded structures, and how to decide when local wave effects, panel modes or global structural motion control the assessment.
Materials, Ductility & Failure
Supports, Connections & Load Paths
Verification & Engineering Workflow
Component & System Response
Blast Response of Plates, Panels & BeamsHow blast-loaded plates, panels and beams move from elastic bending through plastic hinge formation, membrane action and connection-controlled response — and how to choose acceptance measures that reflect the real failure mode.Blast Response of Frames, Enclosures & Equipment StructuresHow local panel response, frame dynamics, enclosure deformation and mounted-equipment loads interact under blast — including load redistribution, internal clearances, support motion and local-to-global model hierarchy.Connections, Anchors & Reaction Transfer Under BlastHow short-duration blast reactions load welds, bolts, anchors, brackets and support interfaces — including stiffness, slip, prying, dynamic reaction transfer, ductility and connection-controlled failure.Layered, Sacrificial & Protective Structural Systems Under BlastHow multi-layer structural systems, sacrificial panels, liners, stand-off skins and protective enclosures share blast energy and reaction — with emphasis on interface behaviour, sequential engagement and protected-structure demand.
Nonlinear & Explicit Analysis
Nonlinear SDOF & Resistance Functions for Blast ResponseHow nonlinear single-degree-of-freedom methods turn component resistance, mass and pulse history into deformation demand — including resistance functions, transformation factors, ductility, support rotation and limitations.Nonlinear & Explicit FEA for Blast Structural ResponseHow to build nonlinear transient and explicit finite-element models for blast-loaded structures — model extent, load application, constitutive behaviour, contact, failure, output selection and solver choice.Blast Explicit FEA — Mesh, Energy & Solution ControlsPractical numerical-quality controls for explicit blast FEA: mesh design, stable timestep, mass scaling, hourglass behaviour, contact energy, artificial damping, localisation and convergence of decision-driving outputs.
Progressive Damage & Residual Capacity
Progressive Damage & Load Redistribution Under BlastHow local yielding, connection failure and stiffness loss can redistribute blast demand through redundant structures — including alternate load paths, cascading failure, modelling boundaries and robust acceptance.Post-Blast Residual Capacity & Damage AssessmentHow to assess permanent deformation, plastic strain, connection damage and remaining load-carrying capability after a blast event — including state transfer, inspection correlation and return-to-service decisions.