When milliseconds make all the difference
In many technical systems, day-to-day operations are stable and predictable. Processes are regulated, structures are designed, and loads are known. Traditional design methods are optimized precisely for these conditions.
But what happens when this stable state is abruptly disrupted?
What if loads do not develop gradually, but rather all at once?
What if energy is introduced into a system within milliseconds?
Then different rules apply.
Highly dynamic events—such as impacts, shock waves, or explosions—are among the scenarios that rarely occur in everyday life but are critical in an emergency. They are difficult to assess intuitively and hard to investigate experimentally. At the same time, they significantly determine the safety, extent of damage, and robustness of a system.
Three typical real-world examples illustrate what matters most.
The Forklift
“It was just a brief moment”
In production environments, forklift movements are part of everyday life. Routes are well-known, and procedures are well-established. This is precisely why minor collisions are often considered non-critical.
From a technical standpoint, however, an impact is not a “simple bump” but a highly dynamic load case. The kinetic energy involved acts on the structure as an impulse. Within a very short time, the following occur:
- local plastic deformations
- complex contact and rebound processes
- high-frequency stress waves within the component
What matters here is not only visible damage, but also whether there is invisible damage that has already reduced the load-bearing capacity—without this being immediately apparent.
The shock wave
“You can’t see her—but she’s there”
In addition to operational or accidental events, there are scenarios in which energy is deliberately and locally concentrated—for example, in the context of safety-related issues or protection concepts.
In such cases, extreme stresses are exerted on materials and structures within a very short period of time:
- Shock waves propagate through the component
- Stresses rise sharply
- Material failure is caused by highly dynamic effects
What is particularly relevant here is not just whether a system fails - but how.
A well-designed system or security concept is characterized by the following:
- Energy is absorbed in a targeted manner
- Failure occurs in a controlled manner
- Critical areas remain protected
The behavior depends heavily on nonlinear effects—such as material models, contact conditions, or failure criteria. These factors can hardly be reliably assessed without simulation.
The Sprinkling
“Targeted—and yet uncontrollable”
In addition to accidental or operational incidents, there are scenarios in which energy is introduced in a targeted and localized manner.
Extreme stresses arise within a very short time:
- Shock waves propagate through the material
- Stresses rise sharply
- Components are suddenly subjected to excessive stress
What appears from the outside to be a single event is, in reality, a highly complex process involving waves, reflections, and local interferences.
Here, too, the question is not:
Whether something fails - but how.
Does a system fail in a controlled manner?
Do critical areas remain protected?
Or does a chain reaction occur?
This is particularly crucial for protection systems.
After all, they are not meant to be indestructible—but to respond in a targeted manner.
And here, too, the following applies:
Real-world testing is only possible to a limited extent.
Simulation makes these scenarios accessible.
Similarities
When time is no longer an issue
Three different situations.
One common principle.
Everything happens extremely quickly.
Decisions are made in milliseconds:
- Energy input and distribution
- Wave propagation in the system
- Onset and progression of material failure
Traditional approaches reach their limits here.
Linear assumptions no longer hold true.
Experience alone is not enough.
What you need is a tool designed specifically for such situations:
Explicit simulation methods.
They make it possible to model these highly dynamic processes step by step—at exactly the same speed at which they occur in reality.
Not as an approximation.
But as a physically accurate representation.
And that is precisely where the added value lies:
Not just reacting after something happens.
But understanding in advance what would happen.
Conclusion: It’s not the event that matters - it’s the reaction
Whether it’s an impact, a shock wave, or a targeted load:
The question isn’t whether such events can occur.
The crucial question is:
How will your system react when it happens?
This is exactly where simulation comes in. It reveals what often remains hidden in real-world testing—and provides the foundation for informed decisions in development, design, and safety.
Let’s calculate your scenario together.
Yours Stefan Merkle
P.S.: For anyone wondering why Merkle CAE is virtually blowing up buildings, here’s some background:
As part of this investigation, the blast effect on a historic building constructed of rubble masonry was analyzed using a highly dynamic, explicit simulation. The goal was to mathematically recreate the actual damage pattern of a historical event as precisely as possible and to draw conclusions about the underlying explosive charge.
To this end, several explosion scenarios involving different quantities of explosives were analyzed with regard to:
- Degree of damage to load-bearing structures
- Behavior of masonry, roof, and concrete ring beam
- Debris distribution and throw distances
compared with one another.
The simulations clearly show that even brief, highly dynamic loads lasting on the order of milliseconds are sufficient to trigger significant structural damage and complex failure mechanisms.
Key finding
A comparison with the historical damage pattern leads to a clear conclusion:
👉 An explosive charge of about 5 kg of TNT provides the best match with the actual damage pattern.
Larger explosive charges result in significantly greater destruction, which is no longer consistent with the documented damage.
Classification
The study clearly demonstrates:
How sensitive structures are to short-term dynamic loads.
Just how complex the interplay between shock waves, structure, and material failure is
And how important simulation is for making such events comprehensible and assessable
At the same time, the limitations become clear:
Simplifications in the model (e.g., regarding contact, debris interaction, or fluid-structure interaction) influence the results—yet still provide a reliable basis for assessment.
PPS:
Maik hat beim Korrekturlesen sich an seine Weimarer Vergangenheit erinnert und sich und seine kleinen elektronischen Helferlein von der Muse küssen lassen. Da das gar nicht schlecht ist, was dabei zum Thema „Druckwelle“ herausgekommen ist, möchte ich es Ihnen nicht vorenthalten:
„Man sieht sie nicht – doch sie ist da“
Wer reitet so leise durch stählernen Raum?
Die Anlage summt wie ein träumender Traum.
Die Drücke sind ruhig, die Werte sind klar,
Die Ordnung besteht – wie sie immer schon war.
Die Temperatur hält die Grenze genau,
Die Strömung ist stetig, berechenbar schlau.
„So soll es sein“, flüstert die Maschine bedacht –
Doch im Gleichmaß der Zahlen erwacht eine Macht.
Es braucht keinen Donner, kein gleißendes Licht,
Kein Warnsignal kündet: „Gefahr in Sicht!“
Ein Leck nur, verborgen, ein Fehler, so klein,
Ein Spiel der Zustände – es fügt sich hinein.
„Man sieht sie nicht“ – doch sie regt sich im Kern,
Geboren im Stillen, im Innersten fern.
Kein Feuer, kein Knall, der die Sinne erschüttert,
Nur Druck, der sich heimlich im Raume verflittert.
Er wächst in der Stille, lokal und doch schnell,
Entweicht jeder Ahnung, entzieht sich dem Quell
Des Denkens, des Handelns – zu rasch ist sein Lauf,
Kein Mensch hält den Atem der Welle noch auf.
Sie trifft auf die Wände, auf Stahl und Gestalt,
Auf Schrauben, Verbindungen – alles wird kalt.
Reflexionen tanzen, sie kreuzen sich wild,
Verstärken sich plötzlich – ein unsichtbares Bild.
In Bruchteilen Sekunden, so flüchtig wie Zeit,
Wird Last zur Gewalt, wird Grenze zu Leid.
Was eben noch ruhig in Ordnung bestand,
Wird plötzlich geprüft von der unsichtbaren Hand.
„Bleibt alles nun dicht?“ – so fragt leis der Raum,
„Oder öffnet ein Spalt sich im tragenden Traum?“
Ein Flüstern im Material, ein Riss, kaum gedacht,
Ein Bauteil vergeht unter wachsender Macht.
Denn keine Geduld wohnt dem Augenblick inne,
Kein Ausgleich, kein Zögern, kein rettende Sinne.
Die Struktur muss entscheiden – sofort, ohne Frist,
Ob sie standhaft noch ist – oder verloren schon ist.
Und wandert die Welle von Kammer zu Raum,
Wird aus einem Flüstern ein rollender Traum.
Ergreift sie das Ganze, das System in Gänz’,
Dann tanzt sie durch Ordnung – zerstörerisch, glänz’.
Wer kann es erforschen, im Reellen so nah?
Ein Versuch wär verheerend – zerstört, was einst war.
Doch genau in der Stille, im unsichtbaren Spiel,
Liegt die Antwort verborgen – das entscheidende Ziel.
Wie hoch ist der Druck, der im Dunkeln erwacht?
Wie schnell seine Reise, wie groß seine Macht?
Wo wachsen die Spitzen, wo endet das Sein?
Und welches Gefüge hält stand – und bleibt rein?
Nicht Gefühl gibt die Antwort, nicht Ahnung, nicht Schein,
Nicht Hoffnung, nicht Zweifel – sie führen nicht ein.
Die Wahrheit liegt tiefer, verborgen, doch klar:
In der Physik –
„Man sieht sie nicht – aber sie ist da.“